Primarily a disease of older adults, cancer is second only to cardiovascular disease as the leading cause of death in the United States (more than 560,000 deaths annually). More than 67% of patients who die of cancer are older than age 65. The most common cancers in the United States are prostate, breast, lung, and colorectal.
Cancer results from a malignant transformation (carcinogenesis) of normal cells. A characteristic feature of cancer cells is their ability to proliferate uncontrollably, thus establishing themselves at other tissues to form secondary foci (metastasis). Additionally, cancer cells serve no useful purpose. (See Comparing benign and malignant tumors.) Cancer cells metastasize via the circulation through the blood or lymphatics, by unintentional transplantation from one site to another during surgery, and by local extension. (See How cancer metastasizes, pages 48 and 49.)
Classified by their histologic origin, tumors derived from epithelial tissues are called carcinomas; from epithelial and glandular tissues, adenocarcinomas; from connective, muscle, and bone tissues, sarcomas; from glial cells, gliomas; from pigmented cells, melanomas; and from plasma cells, myelomas. Cancer cells derived from erythrocytes are known as erythroleukemia; from lymphocytes, leukemia; and from lymphatic tissue, lymphoma.
Researchers have found that cancer develops from mutations within the genes of cells. Thus, cancer is a genetic disease. Cancer susceptibility genes are of two types. Some are oncogenes, which activate cell division and influence embryonic development, and some are tumor suppressor genes, which halt cell division.
These genes are typically found in normal human cells, but certain kinds of mutations may transform the normal cells. Inherited defects may cause a genetic mutation, whereas exposure to a carcinogen may cause an acquired mutation. Current evidence indicates that carcinogenesis results from a complex interaction of carcinogens and accumulated mutations in several genes.
In animal studies of the ability of viruses to transform cells, some human viruses exhibit carcinogenic potential. For example, the Epstein-Barr virus, the cause of infectious mononucleosis, has been linked to Burkitt's lymphoma and nasopharyngeal cancer.
High-frequency radiation, such as ultraviolet and ionizing radiation, damages the genetic material known as deoxyribonucleic acid (DNA), possibly inducing genetically transferable abnormalities. Other factors, such as a person's tissue type and hormonal status, interact to potentiate radiation's carcinogenic effect. Examples of substances that may damage DNA and induce carcinogenesis include:
❑alkylating agents — leukemia
❑aromatic hydrocarbons and benzopyrene (from polluted air) — lung cancer
❑asbestos — mesothelioma of the lung
❑tobacco — cancer of the lung, oral cavity and upper airways, esophagus, pancreas, kidneys, and bladder
❑vinyl chloride — angiosarcoma of the liver.
Diet has also been implicated, especially in the development of GI cancer as a result of a high animal fat diet. Additives composed of nitrates and certain methods of food preparation — particularly charbroiling — are also recognized factors.
The role of hormones in carcinogenesis is still controversial, but it seems that excessive use of some hormones, especially estrogen, produces cancer in animals. Also, the synthetic estrogen diethylstilbestrol causes vaginal cancer in some daughters of women who were treated with it. It's unclear, however, whether changes in human hormonal balance retard or stimulate cancer development.
Some forms of cancer and precancerous lesions result from genetic predisposition either directly (as in Wilms' tumor and retinoblastoma) or indirectly (in association with inherited conditions such as Down syndrome or immunodeficiency diseases). Expressed as autosomal recessive, X-linked, or autosomal dominant disorders, their common characteristics include:
❑early onset of malignant disease
❑increased incidence of bilateral cancer in paired organs (breasts, adrenal glands, kidneys, and eighth cranial nerve [acoustic neuroma])
❑increased incidence of multiple primary malignancies in nonpaired organs
❑abnormal chromosome complement in tumor cells.
Other factors that interact to increase susceptibility to carcinogenesis are immunologic competence, age, nutritional status, hormonal balance, and response to stress. Theoretically, the body develops cancer cells continuously, but the immune system recognizes them as foreign cells and destroys them. This defense mechanism, known as immunosurveillance, has two major components: humoral immune response and cell-mediated immune response. Their interaction promotes antibody production, cellular immunity, and immunologic memory. Presumably, the intact human immune system is responsible for spontaneous regression of tumors.
Theoretically, the cell-mediated immune response begins when T lymphocytes become sensitized by contact with a specific antigen. After repeated contacts, sensitized T cells release chemical factors called lymphokines, some of which begin to destroy the antigen. This reaction triggers the transformation of an additional population of T lymphocytes into “killers” of antigen-specific cells — in this case, cancer cells.
Similarly, the humoral immune response reacts to an antigen by triggering the release of antibodies from plasma cells and activating the serum-complement system, which destroys the antigen-bearing cell. However, an opposing immune factor, a “blocking antibody,” enhances tumor growth by protecting malignant cells from immune destruction.
Theoretically, cancer arises when any one of several factors disrupts the immune system:
❑Aging cells, when copying their genetic material, may begin to err, giving rise to mutations. The aging immune system may not recognize these mutations as foreign and thus may allow them to proliferate and form a malignant tumor.
❑Cytotoxic drugs decrease antibody production and destroy circulating lymphocytes.
❑Extreme stress or certain viral infections can depress the immune system.
❑Increased susceptibility to infection commonly results from radiation, cytotoxic drug therapy, and lymphoproliferative and myeloproliferative diseases, such as lymphatic and myelocytic leukemia. These cause bone marrow depression, which can impair leukocyte function.
❑Acquired immunodeficiency syndrome weakens cell-mediated immunity.
❑Cancer itself is immunosuppressive; advanced cancer exhausts the immune response. (The absence of immune reactivity is known as anergy.)
A thorough medical history and physical examination should precede sophisticated diagnostic procedures. Useful tests for the early detection and staging of tumors include X-ray, endoscopy, isotope scan, computed tomography scan, and magnetic resonance imaging, but the single most important diagnostic tool is a biopsy for direct histologic study of tumor tissue. Biopsy tissue samples can be taken by curettage, fluid aspiration (pleural effusion), fine-needle aspiration biopsy (breast), dermal punch (skin or mouth), endoscopy (rectal polyps), and surgical excision (visceral tumors and nodes).
An important tumor marker, carcinoembryonic antigen (CEA), although not diagnostic by itself, can signal malignancies of the large bowel, stomach, pancreas, lungs, and breasts. CEA titers range from normal (less than 5 ng) to suspicious (5 to 10 ng) to suspect (over 10 ng). CEA serves many valuable purposes:
❑as a baseline during chemotherapy to evaluate the extent of tumor spread
❑to regulate drug dosage
❑to prognosticate after surgery or radiation
❑to detect tumor recurrence.
Although no more specific than CEA, alpha-fetoprotein — a fetal antigen uncommon in adults — can suggest testicular, ovarian, gastric, and hepatocellular cancers. Beta human chorionic gonadotropin may point to testicular cancer or choriocarcinoma. Other commonly used tumor markers include prostate-specific antigen to detect and monitor prostatic cancer, and CA-125, useful for monitoring ovarian, colorectal, and gastric cancers.
Choosing effective therapeutic options depends on correct staging of malignant disease, commonly with the internationally known TNM staging system (tumor size, nodal involvement, metastatic progress). This classification system provides an accurate tumor description that's adjustable as the disease progresses. TNM staging allows reliable comparison of treatments and survival rates among large population groups; it also identifies nodal involvement and metastasis to other areas.
Grading, another way to define a tumor, classifies the lesion according to corresponding normal cells, such as lymphoid or mucinous lesions; it compares tumor tissue to normal cells (differentiation); and it estimates the tumor's growth rate. For example, a low-grade tumor typically has cells more closely resembling normal cells, whereas a high-grade tumor has poorly differentiated cells.
Cancer treatments include surgery, radiation, chemotherapy, biotherapy (also called immunotherapy), and hormonal therapy. Therapies may be used alone or in combination, depending on the type, stage, localization, and responsiveness of the tumor and on limitations imposed by the patient's clinical status.
Surgery, once the mainstay of cancer treatment, is usually combined with other therapies. Surgery may be performed as a biopsy to obtain tissue for study; as continued surgery to remove the bulk of the tumor; or before chemotherapy or radiation to debulk the tumor in hope of a better outcome. Surgery can be curative as well.
Later, other therapies may be used to discourage proliferation of residual cells. Surgery can also relieve pain, correct obstruction, and alleviate pressure. Today's less radical surgical procedures (such as lumpectomy instead of radical mastectomy) are more acceptable to patients.
Radiation therapy aims to destroy the dividing cancer cells while damaging nonmalignant cells as little as possible. Therapeutic radiation is either particulate or electromagnetic. Both types ionize matter and have cellular DNA as their target.
Radiation treatment approaches include external beam radiation and intracavitary and interstitial implants. The latter therapy requires personal radiation protection for all staff members who come in contact with the patient.
Normal and malignant cells respond to radiation differently, depending on blood supply, oxygen saturation, previous irradiation, and immune status. Generally, normal cells recover from radiation faster than malignant cells. The success of the treatment and damage to normal tissue also vary with the intensity of the radiation. Although a large single dose of radiation has greater cellular effects than fractions of the same amount delivered sequentially, a protracted schedule allows time for normal tissue to recover in the intervals between individual sublethal doses.
Radiation may be used palliatively to relieve pain, obstruction, malignant effusions, cough, dyspnea, ulcerations, and hemorrhage; it can also promote the repair of pathologic fractures after surgical stabilization and delay tumor spread.
Combining radiation and surgery can minimize radical surgery, prolong survival, and preserve anatomic function. For example, preoperative doses of radiation shrink a tumor, making it operable, while preventing further spread of the disease during surgery. After the wound heals, postoperative doses prevent residual cancer cells from multiplying or metastasizing.
Systemic adverse effects, such as weakness, fatigue, anorexia, nausea, vomiting, and anemia, may subside with antiemetics, steroids, frequent small meals, fluid maintenance, and rest. They are seldom severe enough to require discontinuing radiation but may require a dosage adjustment. (For localized adverse effects, see Radiation's adverse effects, page 52.)
Radiation therapy involves frequent blood counts (particularly of white blood cells and platelets), especially if the target site involves areas of bone marrow production. Radiation also requires special skin care, such as covering the irradiated area with loose cotton clothing and avoiding deodorants, colognes, and other topical agents during treatment. (See How to prepare the patient for external radiation therapy, page 53.)
Chemotherapy includes a wide array of drugs, which may induce regression of a tumor and its metastasis. It's particularly useful in controlling residual disease and, as an adjunct to surgery or radiation therapy, it can induce long remissions and sometimes effect cures, especially in patients with childhood leukemia, Hodgkin's disease, choriocarcinoma, or testicular cancer. As a palliative treatment, chemotherapy aims to improve the patient's quality of life by temporarily relieving pain and other symptoms.
Some major chemotherapeutic agents include:
❑alkylating agents and nitrosoureas, which inhibit cell growth and division by reacting with DNA
❑antimetabolites, which prevent cell growth by competing with metabolites in the production of nucleic acid
❑antitumor antibiotics, which block cell growth by binding with DNA and interfering with DNA-dependent ribonucleic acid synthesis
❑plant alkaloids, which prevent cellular reproduction by disrupting cell mitosis
❑steroid hormones, which inhibit the growth of hormone-susceptible tumors by changing their chemical environment.
The adverse effects of chemotherapy vary. Antineoplastic agents, toxic to cancer cells, can also cause transient changes in normal tissues, especially among proliferating body cells. For example, antineoplastic agents typically suppress bone marrow, causing anemia, leukopenia, and thrombocytopenia; irritate GI epithelial cells, causing nausea and vomiting; and destroy the cells of the hair follicles and skin, causing alopecia and dermatitis. Some chemotherapy drugs can also have permanent effects such as peripheral neuropathy.
Some I.V. chemotherapy drugs are irritants; others are vesicants. Irritants can cause pain at the injection site and along the vein but usually don't cause tissue necrosis. However, vesicants, extravasated, may cause deep cutaneous necrosis requiring debridement and skin grafting. (Note: Most drugs with the potential for direct tissue injury are now given through a central venous catheter.)
Therefore, all patients undergoing chemotherapy need special care:
❑Watch for any signs of infection, especially if the patient is receiving simultaneous radiation treatment. Be alert for even a low-grade fever when the granulocyte count falls below 500/µl; take the patient's temperature often.
❑Increase the patient's fluid intake before and throughout chemotherapy.
❑Inform the patient of possible temporary hair loss, and reassure him that his hair should grow back after therapy ends. Suggest a wig or other head covering, and encourage the patient to purchase it before the hair loss.
❑Check skin for petechiae, ecchymoses, chemical cellulitis, and secondary infection during treatment.
❑Minimize tissue irritation and damage by checking needle placement before and during infusion if you administer the drug by a peripheral vein. Tell the patient to report any discomfort during infusion. If a vesicant extravasates, stop the infusion, aspirate the drug from the needle, and give the appropriate antidote if available.
Chemotherapeutic drugs can be given orally, subcutaneously, I.M., I.V., intracavitarily, intrathecally, intraperitoneally, topically, intralesionally, and by arterial infusion, depending on the drug and its pharmacologic action; usually, administration is intermittent to allow for bone marrow recovery between doses. Dosages are calculated according to the patient's body surface area, with adjustments for general condition, degree of myelosuppression, and weight changes. When calculating dosage, make sure your information is current because dosages change periodically.
Because many patients approach chemotherapy with apprehension, allow them to express their concerns, and provide simple and truthful information. Explain that not all patients who undergo chemotherapy experience nausea and vomiting and, for those who do, antiemetic drugs, relaxation therapy, and diet can minimize these problems.
Biotherapy (also known as immunotherapy) relies on treatment agents known as biological response modifiers. Biological agents are usually combined with chemotherapeutic drugs or radiation therapy. Much of the work done in biotherapy is still experimental. However, the Food and Drug Administration has approved several new drugs, which are providing promising results. For example, rituximab — a monoclonal antibody — is effective for treatment of relapsed or refractory B-cell non-Hodgkin's lymphoma.
The main biotherapy agent classifications include interferons, interleukins, hematopoietic growth factors, and monoclonal antibodies. Interferons have antiviral, antiproliferative, and immunomodulary effects. The interleukins exert their effects on the T lymphocytes. Monoclonal antibodies such as rituximab provide the most tumor-specific therapy for cancer by selectively binding to tumor cell surfaces.
Although not used to treat cancer directly, hematopoietic growth factors are used to increase the patient's blood counts when chemotherapy or radiation causes a decrease.
The adverse effects of biotherapeutic agents mimic the body's normal immune response with flulike symptoms being the most common.
Hormonal therapy is based on studies showing that certain hormones affect the growth of certain cancer types. For example, the gonadotropin-releasing hormone analogue leuprolide is used to treat prostate cancer. With long-term use, this hormone inhibits testosterone release and tumor growth, and tamoxifen, an antiestrogen hormonal agent, blocks estrogen receptors in breast tumor cells that require estrogen to thrive. Additionally, tamoxifen can be given prophylactically to women at high risk for breast cancer.
Hormone-receptive tumors may be treated with aromatase inhibitors (anastrozole, exemestane, letrozole, testolactone), which inhibit the conversion of adrenal androgens to estrogens, thereby inhibiting the growth of hormone-dependent tumors.
Some adverse effects of these hormonal agents include hot flashes, sweating, impotence, decreased libido, nausea and vomiting, and blood dyscrasias (with tamoxifen).
Tumors grow at the expense of normal tissue by competing for nutrients; consequently, the cancer patient commonly suffers protein deficiency. Cancer treatments themselves produce fluid and electrolyte disturbances, such as vomiting and anorexia. Maintaining adequate nutrition, fluid intake, and electrolyte balance should be a major focus in cancer care.
❑Obtain a comprehensive dietary history to pinpoint nutritional problems and their past causes such as diabetes; help plan the diet accordingly.
❑Ask the dietitian to provide a liquid diet high in proteins, carbohydrates, and calories if the patient can't tolerate solid foods. If the patient has stomatitis, provide soft, bland, nonirritating foods.
❑Encourage the patient's family to bring foods from home, if he requests.
❑Make mealtime as relaxed and pleasant as possible. Encourage the patient to dine with visitors or other patients. Allow choices from a varied menu.
❑With the physician's approval, you may suggest that the patient drink a glass of wine before dinner to stimulate the appetite and aid relaxation.
❑Encourage the patient to drink eight 8-oz (236.6 ml) glasses of noncaffeinated liquids per day. Urge him to drink juice or other caloric beverages instead of water.
❑Suggest small, frequent meals if he can't tolerate normal ones.
❑Avoid strong-smelling foods.
The patient who has had recent head, neck, or GI surgery or who has pain when swallowing can receive nourishment through a nasogastric (NG) tube. If the patient still needs to use the tube after he's discharged, teach him how to insert it, how to test its position in his stomach by aspirating stomach contents, and how to use it to feed himself.
If an NG tube isn't appropriate, other alternatives are gastrostomy, jejunostomy and, occasionally, esophagostomy. These procedures make it possible for you to feed the patient prescribed protein formulas and semiliquids, such as cream soups and eggnog; they also make it easier for the patient to feed himself.
Remember to forewarn the patient that if spilled gastric or intestinal juices come in contact with the abdominal skin, they'll cause excoriation if they aren't washed off immediately. Always flush the tube well with water following each feeding.
Also, to provide adequate hydration, instill about 4 to 6 oz (118 to 177.5 ml) of water or another clear liquid between meals.
After jejunostomy, begin with small feedings, slowly and carefully increasing the amounts. Provide additional fluids and calories during these days of limited food intake by supplementing jejunostomy feedings with I.V. fat emulsions.
Commonly considered an important component of cancer care if the patient can't tolerate enteral nutrition, total parenteral nutrition (TPN) can improve a severely debilitated patient's protein balance. In doing so, TPN characteristically strengthens and conditions the patient, allowing him to better tolerate treatment.
TPN can produce a slight weight gain in the patient receiving radiation therapy, provide optimum nutrition for wound healing, and help the patient combat infection after radical surgery.
Typically, cancer patients have a great fear of overwhelming pain. Therefore, controlling pain is a major consideration at every stage of managing cancer — from localized cancer to advanced metastasis. In cancer patients, pain may result from inflammation of or pressure on pain-sensitive structures, tumor infiltration of nerves or blood vessels, or metastatic extension to bone. Such chronic and unrelenting pain can wear down the patient's tolerance to treatment, interfere with eating and sleeping, and color his life with anger, despair, and anxiety.
Opioid analgesics — either alone or in combination with nonopioid analgesics, antianxiety agents, or tricyclic antidepressants — are the mainstay of pain relief in patients with advanced cancer. In terminal stages of cancer, effective opioid dosages may be quite high because drug tolerance invariably develops. Provide such analgesics generously. Anticipate the need for pain relief, and provide it on a schedule that doesn't allow pain to break through. Don't wait to relieve pain until it becomes severe. Reassure the patient that you'll provide pain medication whenever he needs it. (See Patient-controlled analgesia system.)
Nonpharmacologic pain-relief techniques can be used alone or, more commonly, in combination with drug therapy. Popular techniques include cutaneous stimulation, relaxation, biofeedback, distraction, and guided imagery.
Surgical excision of the tumor can relieve pressure on sensitive tissues and pain caused by inflamed necrotic tissue; treatment with antibiotics can combat inflammation; radiation therapy can shrink metastatic tissue and control bone pain. When a tumor invades nerve tissue, effective pain control requires anesthetics, destructive nerve blocks, electronic nerve stimulation with a dorsal column or transcutaneous electrical nerve stimulator, rhizotomy, or chordotomy.
A holistic approach to patient care modeled after St. Christopher's Hospice in London, hospice care provides comprehensive physical, psychological, social, and spiritual care for terminally ill patients. Although some hospices are located in inpatient settings, most hospice programs serve terminally ill patients amid the more familiar and relaxed surroundings of their own home.
The goal of the hospice care team is to help the patient achieve as full a life as possible, with minimal pain, discomfort, and restriction. Of the many medications provided for pain control, morphine is considered the drug of choice.
Hospice care also emphasizes a coordinated team effort to help the patient and family members overcome the severe anxiety, fear, and depression that occur with terminal illness. As a means to this end, hospice staffs encourage family members to help with the patient's care, thereby providing the patient with warmth and security and helping the family caregivers begin the grieving process before the patient dies.
Everyone involved in this method of care must be committed to high-quality patient care, unafraid of emotional involvement, and comfortable with personal feelings about death and dying. Good hospice care also requires open communication among team members, not just for evaluating patient care but also for helping the staff cope with their own feelings.
No illness evokes as profound an emotional response as the diagnosis of cancer. Patients express this response in several ways. A few face this difficult reality from the outset of diagnosis and treatment. Many use denial as a coping mechanism and simply refuse to accept the truth, but this stance is increasingly difficult for them to maintain. As evidence of the tumor becomes inescapable, the patient may experience clinical depression. Family members may express denial in attempts to cope by encouraging unproven methods of cancer treatment, which can delay effective care. Some patients cope by intellectualizing about their disease, enabling them to obscure the reality of the cancer and regard it as unrelated to themselves. Generally, intellectualization is a more productive coping behavior than denial because the patient is receiving treatment. Be aware of the possible behavioral responses so you can identify them and then interact supportively with the patient and his family. For many malignancies, you can offer realistic hope for long-term survival or remission; even in advanced disease, you can offer short-term achievable goals. To help a patient cope with cancer, make sure you understand your own feelings about it. Then listen sensitively to the patient so you can offer genuine understanding and support. When caring for a patient with terminal cancer, increase your effectiveness by seeking out someone to help you through your own grieving.
Review other book chapters online related to Soft Tissue Sarcoma:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
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