Adenocarcinoma of Prostate Is a common cancer in men. It most frequently affects elderly men, with the incidence increasing with age. The cause of prostate cancer is unknown, but it generally affects the outer group of prostate glands and occurs more frequently in the posterior lobe of the prostate. This disease is most often diagnosed by physical examination and an elevation of acid phosphatase levels in the blood.
Common signs and symptoms associated with prostate cancer include urinary tract obstructions, a hard, enlarged prostate on rectal palpation, and low back pain, often caused by metastatic spread to the pelvis and lumbar spine.
In cases of suspected prostatic disease, MRI or sonographic imaging may be used to determine the location and extent of the disease.
Some types of prostate cancer are fairly dormant, but others are very aggressive and yield a higher mortality rate. If it is diagnosed at an early stage, the initial treatment is surgical removal of the tumor. In addition, this neoplasm is highly testosterone dependent, so the testes are often removed along with the prostate. In some instances, female hormones may be administered to control the growth of the tumor by interfering with testosterone. A new treatment modality involves planting radioactive seeds in the prostate, guided by ultrasound, to destroy the tumor.
Prostate cancer is staged A to D and graded I to III, depending on the extent of the disease. It tends to infiltrate surrounding structures early and extensively, particularly the skeletal system. Skeletal metastases occur in approximately 75% of all cases and manifest on plain radiographs as sclerotic lesions within the bone. Bone pain in an elderly man should particularly raise suspicion about prostate cancer. As the third leading cause of cancer deaths in men, it has a 5-year survival rate of approximately 33%.
Autoimmune Deficiency Syndrome (AIDS) Was first recognized in 1981. It is caused by one of two related human immunodeficiency retroviruses, HIV-1 and HIV-2, and results in a wide range of clinical manifestations. HIV-1 paralyzes the normal immune mechanisms within the human body, resulting in severe immunosuppression, or AIDS. It is responsible for most cases of AIDS in the Western hemisphere. Retroviruses contain reverse transcriptase, an enzyme that converts viral RNA into a DNA copy that becomes integrated into the host cell DNA. Each time the cell divides, the retroviral DNA is duplicated. Both types of HIV also contain HIV protease, an enzyme that converts immature, noninfectious HIV to its infectious state within the cell. The HIV infects a part of the T lymphocytes termed T4 or CD4 as well as nonlymphoid cells such as macrophages. Infected individuals experience a brief antibody-negative period immediately after infection, during which time the virus rapidly reproduces until the immune system begins to react to the infectious agent.
Although it can affect anyone, regardless of age or sexual orientation, HIV most frequently affects homosexual and bisexual men and intravenous (IV) drug users. The virus is transmitted through sexual contact and exposure to infected blood and body fluids.
Because HIV inhibits the body’s response to the presence of a variety of diseases, one major sign of AIDS is the presence of unusual opportunistic infections such as Pneumocystis carinii, Toxoplasma gondii, cryptococci, Mycobacterium avium, and herpes. AIDS is also directly linked to an increased incidence of malignancies such as Kaposi’s sarcoma, non-Hodgkin’s lymphoma (NHL), Hodgkin’s disease, and primary CNS lymphoma. It is the most common disease associated with lymphocytopenia or the depletion of lymphocytes. This occurs through the destruction of CD4+ T cells infected by the virus. Anemia, thrombocytopenia, and leukopenia also commonly occur in HIV-infected patients.
One of the most common lung infections associated with HIV is tuberculosis (TB). The lungs are also a common site for opportunistic infections associated with AIDS such as Pneumocystis carinii pneumonia, often in combination with a cytomegalovirus. The typical early radiographic finding of P. carinii pneumonia is a hazy, perihilar, granular infiltrate that spreads to the periphery and appears predominantly interstitial. In later stages the pattern progresses to patchy areas of air-space consolidation with air bronchograms, indicating the alveolar nature of the process. The radiographic appearance may closely resemble pulmonary edema or bacterial pneumonia.
Kaposi’s sarcoma is the most common malignancy in AIDS patients, especially in homosexual or bisexual men who are often co-infected with herpes virus 8. It is present in approximately 25% to 30% of AIDS patients and may affect the connective tissue in various sites within the body. It most often affects the skin (ulcerated hemorrhagic dermatitis), lymph nodes, and gastrointestinal system. About 20% of patients with Kaposi’s sarcoma also demonstrate pulmonary involvement. Radiographically, patients present hilar adenopathy, nodular pulmonary infiltrates, and pleural effusion. Endobronchial Kaposi’s sarcoma is frequent and may result in atelectasis or postobstruction pneumonia.
About 40% of all AIDS victims have neurologic symptoms, most commonly progressive dementia. Patients who develop mass lesions of the brain commonly have focal neurologic symptoms and signs.
MRI best demonstrates the multiple manifestations of AIDS in the central nervous system. Atypical brain abscesses and meningeal infection often occur, most commonly related to toxoplasmosis, cryptococcosis, cytomegalovirus, and herpesvirus. Increasing evidence indicates that cerebral infections may manifest from the HIV itself. Patients with AIDS also have a high incidence of lymphoma involving the central nervous system.
Signs and symptoms associated with HIV and AIDS are broad and may mimic other diseases. Symptoms of HIV infection include generalized lymphadenopathy, malaise, fever, and joint pain within 1 to 4 weeks after infection. These early-stage HIV symptoms may last up to 10 years before progressing to AIDS. Left untreated, approximately 99% of HIV infections progress to AIDS. As this progression takes place, weight loss may occur as a result of nausea, vomiting, and diarrhea. As mentioned earlier, leukopenia, anemia, and thrombocytopenia also occur. AIDS can affect the CNS, resulting in apathy, memory loss, inability to concentrate, and dementia. Headaches, fever, or photophobia associated with acute aseptic meningitis, encephalopathy with seizures, or motor, sensory, or gait deficits may be the first manifestations of the disease. Atrophy of the brain cortex is commonly demonstrated on brain CT and MRI studies in patients with subacute encephalitis related to AIDS. In cases of toxoplasmic encephalitis, CT and MRI will demonstrate contrast-enhanced lesions within the basal ganglia.
Although much research has been initiated, no cure for AIDS has been found. With no known cure, AIDS remains a major health crisis and places a burden on the health care system. Currently, treatment assists in maintaining quality of life and management of symptoms as they manifest. Antiviral drugs assist in suppressing the HIV infection. A healthy lifestyle free of stress, alcohol, and illegal drugs is recommended. HIV carriers should avoid infections if possible because they may accelerate the HIV process. Highly active antiretroviral therapy (HAART) has reduced the incidence of opportunistic infections and extended the lives of individuals infected with AIDS. Currently, the most common therapy calls for a three-drug regimen to include reverse transcriptase inhibitors and protease inhibitors. Bone marrow evaluation is common in HIV-positive individuals. This diagnostic tool is used to evaluate decreased blood cell counts, to stage malignancies, and to obtain cultures for associated infections.
Cervical Carcinoma Is the third most common form of cancer in women. Development of the tumor appears to be related to chronic irritation, infection, and poor hygiene. A higher incidence occurs in women who have begun sexual activity at an early age, have had multiple sexual partners, have evidence of HPV infection (especially certain subtypes) and have had other venereal diseases, such as genital herpes or syphilis. The development of the Pap smear examination has permitted detection of cervical carcinoma at a very early stage (carcinoma in situ—confined to the site of origin), when it has not yet invaded the underlying tissues and is surgically curable. Widespread cervical cancer becomes inoperable, and radiation therapy is the usual treatment.
Carcinoma of the cervix is histologically a squamous cell carcinoma. The earliest lesions are barely recognizable by examination with the naked eye. Colposcopy may be used to identify the mucosal abnormalities. These changes are typically described as “mosaic” or “punctate.” The cervix changes from a normal, smooth pattern to these pathologic patterns as a result of the presence of abnormal cells, irregular maturation of cells, and ingrowth of new blood vessels into the tumor zone.
Once an invasive tumor develops, it may take several forms, classified as exophytic or endophytic, depending on whether the predominant direction of growth is inside or outside of cervix. Exophytic tumors protrude into the vagina and are cauliflower-like fungating masses. Invasive tumors, called endophytic (“inside growing”), usually present as craterlike ulcerations. A variegated appearance is common in advanced cancers, which do not follow any prescribed mode but grow indiscriminately in all directions.
The median age of patients diagnosed with invasive carcinoma of the cervix is 50 years. In contrast, the median age of women diagnosed with CIN is 35 years. Because we know that CIN precedes invasive carcinoma in almost all cases, it is safe to conclude that it takes approximately 15 years for an invasive tumor to develop. During this period, most women have either no symptoms or only nonspecific minor symptoms, such as increased vaginal discharge or bleeding after intercourse. Once the tumor develops, all these symptoms may become more prominent. The discharge ultimately becomes bloody or purulent and foul-smelling. Vaginal bleeding is scant, even in advanced cases, and is not a common finding. Pain is not a feature of cervical cancer, and it occurs only after the tumor has spread extensively beyond the cervix. These symptoms are nonspecific, and it takes a long time for the symptoms to truly interfere with daily life. Without active surveillance, most women with cervical cancer would probably seek medical treatment only after the tumor had spread well beyond the treatable stages.
Advanced carcinoma invades the adjacent organs, most notably the urinary bladder and the rectum, causing urinary urgency or obstruction. Complete urinary tract obstruction causes slowly progressive renal failure, which is still the most common cause of death in these patients. The metastases tend to follow the lymph drainage of the cervix and typically involve the pelvic lymph nodes. Distant metastases to the abdominal and thoracic organs may occur in terminal stages.
At the time of the initial staging, one third of patients have unilateral or bilateral hydronephrosis that can be demonstrated by excretory urography or ultrasound. Indeed, the most common cause of death in patients with carcinoma of the cervix is impairment of renal function caused by ureteral obstruction. Extension of the tumor to the bladder may cause an irregular filling defect; direct infiltration of the perirectal tissues may produce irregular narrowing of the rectosigmoid colon and widening of the retrorectal space. Distant metastases to the skeleton or lungs are uncommon, even in patients with advanced disease.
Because the clinical prognosis of cervical cancer depends primarily on the extent of tumor spread, staging is imperative. This is done according to the following criteria:
Stage 0—no gross lesions; carcinoma limited to the mucosa (CIN III)
Stage I—invasive carcinoma confined to the cervix
Stage II—carcinoma extending beyond the confines of the cervix but not reaching the pelvic wall and not extending below the upper part of the vagina
Stage III—tumor reaching the pelvic wall and/or invading the lower third of the vagina
Stage IV—tumor that has spread beyond the pelvis or has infiltrated the adjacent organs; these tumors are also associated with metastases
The prognosis of carcinoma of the cervix depends primarily on the stage of the tumor. The preinvasive cancer (CIN) is curable, whereas stage IV cancer is almost always lethal and has a 5-year survival rate of 15%.
Ultrasound usually demonstrates a cervical carcinoma as a solid mass behind the bladder. CT is more accurate in detecting pelvic side wall invasion and therefore is usually the initial staging procedure in patients in whom there is a clinical suspicion of advanced disease. This modality is also the procedure of choice for monitoring tumor response to treatment and for assessing suspected recurrence.
MRI is superior in detecting and staging cervical carcinoma. CT cannot always differentiate tumor from adjacent normal tissue.
After radiation therapy for carcinoma of the cervix (and other types of pelvic carcinoma), it may be difficult to distinguish chronic rectal narrowing and widening of the retrorectal space caused by radiation effects from that caused by recurrence of tumor. Radiation therapy can also lead to the development of fibrous inflammatory adhesions between loops of bowel and the bladder, resulting in the development of fistulas between bowel loops (enteric-enteric) and between a bowel loop and the urinary bladder (enteric-vesicular).
CIN can be resected surgically with a scalpel (knife) or with laser ablation, cryotherapy (freezing), or electrocautery. Advanced lesions are treated surgically, in combination with radiation therapy and chemotherapy.
Fibroadenoma of Breast A common benign breast tumor. It is usually unilateral and consists of a solid, well-defined mass that does not invade surrounding tissue. The neoplasm is formed by an overgrowth of fibrous and glandular tissue and is commonly located in the upper, outer quadrant of the breast. Fibroadenomas almost always occur in women under the age of 30 years and most frequently in those aged 21 to 25 years. Fibroadenomas appear to be estrogen dependent and may grow rapidly during pregnancy. These lesions are often painless and can usually be moved about within the breast. Mammography, in conjunction with physical breast examination and sonography, plays a vital role in the detection of fibroadenomas and is useful in distinguishing them from mammary dysplasia (fibrocystic breast disease) and breast carcinoma. Ultrasound permits differentiation of a solid fibroadenoma from a fluid-filled breast cyst. Surgical removal of the lesion is curative.
Typical tumors measure 2 to 5 cm in diameter and are well encapsulated, round, and lobulated. As the name implies, the tumor is composed of two components: fibrous stroma and glandular epithelium. The fibroblastic component of the tumor corresponds to the hormone-sensitive intralobular connective tissue, whereas the glands represent excretory ducts.
Fibroadenomas are tumors that affect young women. Because they consist of hormonally sensitive cells, it has been hypothesized that the tumors represent an abnormal exaggerated response of breast tissue to sex hormones. These well-encapsulated and sharply demarcated tumors can be shelled out and are removed easily by surgeons without serious consequences. Fibroadenomas do not recur and do not undergo malignant transformation; therefore, they have an excellent prognosis.
New fibroadenomas do not appear, nor are existing ones seen to grow in size, in postmenopausal women, except in women who are having hormonal replacement therapy (HRT).
On mammography a fibroadenoma is seen as a mass which displaces the normal tissues, has a smooth, rounded, well defined margin, but no specific characteristic features. Calcification commonly occurs in fibroadenomata, particularly in those which have been present for some time. When calcification does occur, then it often has an absolutely characteristic ‘popcorn’ appearance on mammography.
Since fibroadenomas are benign, treatment will vary depending on diagnosis. If it is small, painless, remains the same size, and a biopsy shows no problems, further treatment is not needed, but follow-up ultrasounds may be done. However, if it is large (more than three cm), painful, growing, or a biopsy results in atypical (very active) cells, a lumpectomy is performed. New technologies such as laser ablation (using heat) or cryoablation (freezing) may be performed if the patient is a candidate for these types of treatment. In-situ ablation of fibroadenomas can be done in-office, leaves tiny scars, and has fast recovery.
Infertility (Female) The causes of infertility in young women include anomalies in the reproductive organs, such as an abnormal uterus that cannot hold a fetus, obstructed fallopian tubes, ovaries that are unable to produce mature ova, and disruption of the path the ova normally follow en route to the uterus.
The major radiographic procedure for evaluating infertile women is hysterosalpingography, in which the uterine cavity and fallopian tubes are opacified after the injection of contrast material into the uterus. In a woman with normal patent fallopian tubes, contrast material extravasating into the pelvic peritoneal cavity outlines the peritoneal surfaces and often loops of bowel within the pelvis. Developmental anomalies or fibrosis from PID may cause occlusion of one or both of the fallopian tubes; in such cases, there is no evidence of the contrast material reaching the peritoneal cavity. In addition to assessing tubal patency, hysterosalpingography can also demonstrate uterine abnormalities that contribute to infertility, such as intrauterine fibroids, severe uterine flexion or retroversion, and other congenital and acquired malformations. The procedure is indicated for infertility studies and has been used to diagnose and treat a number of different structural and functional pathologic conditions.
For women who receive ovulation-induction agents as treatment for infertility, ultrasound can be used to monitor the maturation of ovarian follicles. Low-level internal echoes in mature ovarian follicles appear to be a prognostic indicator of fertility. They may represent a periovulatory state, which is an appropriate time for artificial insemination or in vitro fertilization.
Decreased fertility has many possible causes:
- Infertility may be associated with hormonal imbalances resulting from altered function of the hypothalamus, anterior pituitary gland, or ovaries. Altered function may occur following the use of oral contraceptives
- Structural abnormalities may prevent pregnancy, for example, a small or bicornuate (divided) uterus
- The fallopian tubes may be obstructed by scar tissue resulting from infection or endometriosis
- Access of viable sperm may be reduced by a change in vaginal pH due to infection or the use of douches, by excessively thick cervical mucus,
or by the development of antibodies in the female to particular sperm; and
- Recent evidence implicates cigarette smoking by either the male or female partner and second-hand smoke as a deterrent to pregnancy
Leukemia Is a term associated with neoplastic disease of leukocytes that results in an overproduction of white blood cells. This increase in leukocytes interferes with normal blood cell production and may lead to anemia, bleeding, and infection. Leukemias can infiltrate lymphatic tissue and organs such as the liver and spleen. The cause of leukemia is unknown, but exposure to irradiation and certain chemicals (especially benzene), as well as genetic defects such as Down syndrome, seem to predispose individuals to developing this disorder. Current research also indicates an association between leukemia and two viruses: the Epstein-Barr virus and the human T-cell leukemia and lymphoma virus.
Leukemias are classified according to cell type and cell maturity. Granulocytic or myelocytic leukemias develop from primitive or stem cells. Monocytic leukemias develop from precursor cells (the cells from which leukocytes are derived) and are the least common type of leukemia. Lymphocytic leukemias arise from lymphoid cells. In addition, leukemias are classified as either acute or chronic. Acute leukemias have an abrupt onset and may manifest as a hemorrhagic episode. They generally are associated with primitive or poorly differentiated cells. Chronic leukemias progress at a relatively slow pace with nonspecific signs such as fatigue and weakness. They are associated with mature or well-differentiated cells. These terms are used in combination to describe the specific type of leukemia.
Acute lymphocytic leukemia (ALL) predominantly affects children. Chronic lymphocytic leukemia (CLL) predominantly affects individuals over age 60. Chronic myelocytic leukemia (CML), also called chronic granulocytic leukemia (CGL), most often affects adults between the ages of 20 and 50. Acute myelocytic leukemia (AML) and acute monoblastic leukemia (AMOL) can affect anyone at any age. Leukemias, in general, account for approximately 33% of all cancer deaths in children under the age of 15 years.
Because of the exuberant white cell production, there is generally a decrease in the number of circulating red blood cells and platelets. This results in a typical clinical appearance of weakness, shortness of breath, and cardiac palpitations. A decrease in the number of platelets interferes with the blood-clotting mechanism and results in a bleeding tendency. Even though there are more circulating white blood cells than normal, most are immature and thus the patient becomes highly susceptible to infection. Diffuse infiltration of white cells into the spleen and liver may cause massive enlargement of these organs (hepatosplenomegaly).
In childhood leukemia, radiographically detectable skeletal involvement is extremely common as a result of the infiltration of leukemic cells into the marrow. The earliest radiographic sign of disease is usually a transverse radiolucent band at the metaphyseal ends of the long bones, most commonly about the knees, ankles, and wrists. In infancy this appearance is nonspecific because it also occurs with malnutrition or systemic disease. The presence of these transverse lucent metaphyseal bands after 2 years of age is strongly suggestive of acute leukemia.
As the proliferation of neoplastic cells in the marrow becomes more extensive, actual destruction of bone may occur. This may cause patchy lytic lesions, a permeative moth-eaten appearance, or diffuse destruction with cortical erosion. A reactive response to proliferating leukemic cells can cause patchy or uniform osteosclerosis; subperiosteal proliferation incites the formation of periosteal new bone. Diffuse skeletal demineralization may result in vertebral compression fractures.
Enlargement of mediastinal and hilar lymph nodes is the most common abnormality on chest radiographs. Diffuse bilateral reticular changes may simulate lymphangitic spread of carcinoma. The nonspecific pulmonary infiltrates seen in patients with acute leukemia are usually attributable to hemorrhage or secondary infection.
The radiographic abnormalities in chronic leukemia are often similar to those in the acute disease, although their frequency and degree may vary. Skeletal changes are much less common and are usually limited to generalized demineralization in the flat bones, where active marrow persists in adulthood. The demonstration of focal areas of destruction, or periosteal new bone formation, indicates probable transformation into an acute phase of the disease.
Hilar and mediastinal adenopathy are common, especially in chronic lymphocytic leukemia. Congestive heart failure commonly results from the associated severe anemia.
Splenomegaly is an almost constant finding in patients with chronic leukemia. Leukemic infiltration of the gastrointestinal tract can produce single or multiple intraluminal filling defects and the infiltrative process may be indistinguishable from carcinoma. Renal infiltration can cause bilateral enlargement of the kidneys. In chronic lymphocytic leukemia, enlargement of retroperitoneal or mesenteric lymph nodes can cause displacement or obstruction of structures in the genitourinary or gastrointestinal tracts.
Leukemia treatment may require multidrug chemotherapy, bone marrow transplant, antibiotics to aid in preventing infections, or a transfusion to reverse the blood cell imbalance. Interferon therapy is a drug regimen to aid the body in producing antiviral proteins that decrease the production of leukemia cells, resulting in an increase in the effectiveness of the immune system. Stem cell transplantation (SCT), although controversial and very expensive, helps by increasing the production of normal cells to replace cells damaged or destroyed by radiotherapy and chemotherapy.
Most patients with acute leukemia die within 6 months without treatment. More than 90% of ALLs carry a 5-year remission rate of 50% or better after treatment. AML and AMOL result in 70% to 85% remission after treatment. In all cases survival depends on complete remission. CGL, however, is progressive, with an average survival of about 3 to 4 years after the onset of the disease and a 5-year survival rate of approximately 20%. Radiography plays a limited role in the diagnosis and treatment of most leukemias.
Metastasis Denotes a process in which cells move from one site to another in the body. Only malignant tumor cells have the capacity to metastasize. Benign tumors never metastasize and always remain localized.
The most deadly aspect of cancer is its ability to spread, or metastasize. Cancer cells initially group together to form a primary tumor. Once the tumor is formed, cells may begin to break off from this tumor and travel to other parts of the body. This process is metastasis. These cancer cells that travel through the body are capable of establishing new tumors in locations remote from the site of the original disease. Metastasis is a very complicated process that still has yet to be completely understood.
Metastasis involves a spread of tumor cells from a primary location to some other site in the body. The spread can occur through three main pathways:
- Through the lymphatics
- Via blood, also know as hematogenous spread
- By seeding of the surface of body cavities
If the cancerous cells spread into surrounding tissue by virtue of the close proximity of the areas, it is termed invasion. However, if the cancerous cells travel to a distant site or distant organ system, it is termed seeding. Certain types of cancer appear more often as metastases from other areas rather than originating in a given organ.
Regardless of the pathway for dissemination of tumor cells, the sequence of events leading to metastasis is essentially the same and includes several distinct steps, collectively known as the metastatic cascade (see figure).
Not all malignant cells are capable of metastasis. The first step, then, is acquisition of a capacity to metastasize. Cells that have acquired the capacity to metastasize expand clonally, forming a distinct subpopulation. As this clone expands by successive divisions, its cells reach the lymphatics or the blood vessels or enter a body cavity. The fluid in these spaces (i.e., the lymph in the lymphatics, the blood in the blood vessels, or the pleural and peritoneal fluid) carry the cells from the primary site to distant locations, where the cells attach and begin forming a new tumor mass.
Metastatic cells must escape the deleterious effects of immune cells, such as T lymphocytes, natural killer (NK) cells, and macrophages, which act on circulating tumor cells. To survive at the new site, the malignant tumors must elicit angiogenesis. Such new blood vessels are essential for tumor growth because it is through these vessels that the tumor receives blood, with all its nutrients and oxygen.
Metastatic cascade occurs in several steps, marked 1 through 7.
To metastasize, a cancer cell must break away from its tumor, invade either the circulatory or lymph system, which will carry it to a new location, and establish itself in the new site. The body has many safeguards to prevent cells from doing this, yet many cancer cells have the ability to overcome these safeguards.
When cancer is diagnosed, it may be discovered in a site that is not the location of the primary tumor. Through various means of testing, doctors will locate the primary tumor, and determine to what extent it has spread from that location to other areas of the body. Localized tumors that have not had the opportunity or time to metastasize have the best prognosis for cure. Cancers which have metastasized usually indicate a later stage disease, and treatment becomes more complicated, with poorer outcomes. In late stages, patients with oral cancer for example, may succumb to a cancer in the lungs or the brain, which was not the location of the original, primary tumor.
Metastasis most commonly occurs by way of the bloodstream or the lymphatic system. Just like normal cells, cancer cells must have a blood supply in order to function. They have access to the bloodstream just as healthy cells do. This access allows detached malignant cells from the tumor to enter the bodies’ general bloodstream. Once in the bloodstream, the cancer cells now have access to every portion of the body. The lymphatic system has its own channels throughout the body like the circulatory system, through which a malignant cell can travel. When surgeons remove a tumor, they may also remove nearby portions of the lymph system including the lymph nodes, as these are frequently the first sites of the cancers’ metastasis. Once metastasis to the lymphatic system has occurred, the prognosis for cure drops significantly.
Besides binding to each other, cells also adhere to the extracellular matrix. The matrix is composed of connective tissue proteins such as collagen and elastin which interact to form highly insoluble materials. The extracellular matrix not only binds cells together, it also allows cells to survive and proliferate. Research has shown that cells have anchorage dependence. This means that a cell cannot reproduce unless it is attached to a surface. This attachment is made possible through cell surface molecules called integrins, which bind to the extracellular matrix. Only after the cell has attached to a surface will it begin its reproductive cycle. Unattached cells neither reproduce, nor grow.
The halting of growth and reproduction of unattached cells is one of the body’s safeguards to maintain the integrity of tissues. Normal cells have specific places in which they must stay in order to survive. However, cancer cells are able to exist without being anchored. Oncogenes are mutated versions of proto-oncogenes, which are present in healthy cells, and are capable of turning normal cells into malignant cells. It is possible that in cancer cells, proteins made by oncogenes may convey a false message that the cell is attached when it is not. This allows the cancer cell to continue to grow and reproduce when it should be engaging in apoptosis, or programmed cell death.
Once a cancer cell has detached from other cells and the extracellular matrix, it must make its way into a blood or lymphatic circulatory system to transport itself. A common way for transport is the bloodstream, since blood vessels are often nearby. Tumors are capable of creating new blood vessels (angiogenesis) because of their need for nutrition, and this gives cancer cells ample opportunity for transport. Entry to the blood vessel requires penetration of the basement membrane. The basement membrane is a thin layer of specialized extracellular matrix. Basement membranes surround blood vessels but they are also present with epithelial cells. Epithelial cells which are the most common sources of cancer, have a basement membrane separating them from the rest of the body. With cancerous tumors that develop in epithelial cells, a cancer cell must penetrate two basement membranes, the epithelial and blood vessel, for transport. To breach the basement membrane cancer cells release enzymes that dissolve basement membranes and other extracellular matrices, allowing penetration of the basement membrane of blood vessels, giving the cancer cells access to other parts of the body.
The lungs and the liver are the two most common sites for metastasis in the human body.
In the primary tumor itself, only certain cancer cells can metastasize. Not all cancer cells have the tools to survive the journey to another area of the body. Many circulating cancer cells die because they are not equipped for the entire process of metastasis. Properties in the tumor itself, such as deformability, aggregation, and expression of adhesive molecules, prevent cancer tumor cells from surviving detachment from the tumor. The host also has weapons, such as blood turbulence, platelets, T cells, natural killer cells, and macrophages, that kill circulating cancer cells. Tumor cells that reach their destination may not be able to respond to specific organ factors, and this will kill the tumor cells as well.
Pelvic Inflammatory Disease (PID) is an infection of the reproductive tract, particularly the fallopian tubes and ovaries. The condition includes cervicitis (cervix), endometritis (uterus), salpingitis (fallopian tubes), and oophoritis (ovaries). The infection may be acute or chronic. PID is a common problem and is a matter of concern because of the potential acute complications such as peritonitis and pelvic abscess as well as the long-term problems of infertility and the high risk of ectopic pregnancy.
The infection usually originates as a vaginitis or cervicitis and is polymicrobial, often involving several causative bacteria. The disease may result from an unsterile abortion or introduction of a pathogen from other sources. This inflammation is generally bilateral, and without treatment the infection spreads to the peritoneum, resulting in bacteremia. Tuboovarian abscess formation may also occur with PID, often resulting in sterility. Pelvic abscesses may be life threatening if not quickly drained surgically. Infection may spread, resulting in septicemia. The most common cause of death in women with PID is septic shock.
The majority of infections arise from sexually transmitted diseases such as gonorrhea (Neisseria gonorrhoeae) and chlamydiosis (Chlamydia trachomatis). One third of cases are caused by gonococcus, one third are caused by a mixture of infections, and the last third of cases are caused by Staphylococcusor Streptococcusbacteria.
Occasionally, infection in the reproductive tract may result from bloodborne organisms or from an infection in the peritoneal cavity related to conditions such as appendicitis.
A prior episode of vaginitis or cervicitis, often with few signs, frequently precedes the development of PID. Infection is likely to become acute during or immediately following menses, when the endometrium is more vulnerable.
Adhesions and strictures are common sequelae; they affect the tubes and ovaries, leading to infertility or ectopic pregnancy (implantation of the fertilized ovum in the fallopian tube). Adhesions or scar tissue may also affect the surrounding structures such as the colon.
PID may also result from insertion of an intrauterine device (IUD, a contraceptive device) or other instrument contaminated by organisms from the lower reproductive tract or other source. Any instrument or device is likely to traumatize the tissue or perforate the wall, leading to inflammation and infection. Infection may also be associated with abortion or childbirth. Historically, PID was the feared complication of illegal abortions or deliveries under primitive conditions.
Lower abdominal pain is usually the first indication of PID. Pain may be sudden and severe or gradually increasing in intensity. Characteristically, it is a steady pain that increases with walking. Tenderness is common during pelvic examination. Purulent discharge is evident at the cervical os. Dysuria may be noted. Fever and leukocytosis depend on which causative organisms are involved. Peritonitis is indicated by increasing abdominal distention and rigidity.
The most common treatment of PID is aggressive antibiotic therapy, but healing often results in scarring and obstruction of the fallopian tubes, which predisposes the individual to ectopic pregnancy because of the tubal narrowing. Rupture of the fallopian tubes because of infection can result in septic shock and can be a life-threatening situation. Sonography is commonly indicated as an imaging method for determining the presence of infection and the extent of the disease. Severe cases with abscess formation may also require surgical intervention. Recurrent infections are common, and therefore it is recommended that sexual partners be treated with antibiotics and that follow-up examinations are scheduled to ensure complete eradication of the infection.