Friday, May 5, 2017

Introduction to Breast cancer

Breast cancer is the most common cancer affecting women and is the number two killer (after lung cancer) of women ages 35 to 54. It occurs in men, though only rarely. (See Breast cancer in men.) The overall breast cancer death rate for American women has fallen. Lymph node involvement is the most valuable prognostic predictor. With adjuvant therapy, 70% to 75% of women with negative nodes will survive 10 years or more, compared with 20% to 25% of women with positive nodes.
Although breast cancer may develop anytime after puberty, it’s most common after age 50.

The cause of breast cancer is unknown, but its high incidence in women implicates estrogen. Certain predisposing factors are clear; women at high risk include those who:
  • have a family history of breast cancer
  • have long menses; began menses early or menopause late
  • have never been pregnant
  • were first pregnant after age 31
  • have had unilateral breast cancer
  • have had endometrial or ovarian cancer
  • have been exposed to low-level ionizing radiation.
Many other predisposing factors have been investigated, including estrogen therapy, antihypertensives, high-fat diet, obesity, and fibrocystic disease of the breasts.
Women at lower risk include those who:
  • were pregnant before age 20
  • have had multiple pregnancies
  • are Indian or Asian.
Breast cancer is more common in the left breast than in the right and more common in the upper outer quadrant. Growth rates vary. Theoretically, slow-growing breast cancer may take up to 8 years to become palpable at 1 cm in size. It spreads by way of the lymphatic system and the bloodstream, through the right side of the heart to the lungs and, eventually, to the other breast, the chest wall, liver, bone, and brain.
Many refer to the estimated growth rate of breast cancer as doubling time, or the time it takes the malignant cells to double in number. Survival time for breast cancer is based on tumor size and spread; the number of involved nodes is the single most important factor in predicting survival time.
Classified by histologic appearance and location of the lesion, breast cancer may be:
adenocarcinoma—arising from the epithelium
intraductal—developing within the ducts (includes Paget’s disease)
infiltrating—occurring in parenchymatous tissue of the breast
inflammatory (rare)—reflecting rapid tumor growth, in which the overlying skin becomes edematous, inflamed, and indurated
lobular carcinoma in situ—reflecting tumor growth involving lobes of glandular tissue
medullary or circumscribed—a large tumor with a rapid growth rate.
Signs and symptoms
Warning signals of breast cancer include:
  • a lump or mass in the breast (a hard, stony mass is usually malignant)
  • a change in symmetry or size of the breast
  • a change in breast skin (thickening, scaly skin around the nipple, dimpling, edema [peau d’orange], or ulceration)
  • a change in skin temperature (a warm, hot, or pink area; suspect cancer in a non-breast-feeding woman past childbearing age until proven otherwise)
  • unusual drainage or discharge (a spontaneous discharge of any kind in a non-breast-feeding woman warrants thorough investigation; so does any discharge produced by breast manipulation [greenish black, white, creamy, serous, or bloody]). If a breast-feeding infant rejects one breast, this may suggest possible breast cancer.
  • a change in the nipple, such as itching, burning, erosion, or retraction
  • pain (not usually a symptom of breast cancer unless the tumor is advanced, but it should be investigated)
  • bone metastasis, pathologic bone fractures, and hypercalcemia
  • edema of the arm.
Diagnostic measures for breast cancer include the following.
  • Breast self-examination
  • Although not proven to lower mortality rates, breast self-examination may detect palpable breast lumps, allowing the woman to contact her physician for early evaluation.
  • Mammography and biopsies
  • Other diagnostic measures include mammography, a needle biopsy, and a surgical biopsy. Mammography is indicated for any woman whose physical examination might suggest breast cancer. It should be done as a baseline on women ages 35 to 39, every 1 to 2 years for women ages 40 to 49, and annually for women older than age 50, women who have a family history of breast cancer, and women who have had unilateral breast cancer, to check for new disease. However, the value of mammography is questionable for women younger than age 35 (because of the density of the breasts), except those who are strongly suspected of having breast cancer.
  • False-negative results can occur in as many as 30% of all tests. Consequently, with a suspicious mass, a normal mammogram result should be disregarded, and a fine-needle aspiration or surgical biopsy should be done. Ultrasonography, which can distinguish a fluid-filled cyst from a tumor, can also be used instead of an invasive surgical biopsy.
Other tests
Bone scan, computed tomography scan, measurement of alkaline phosphatase levels, liver function studies, and a liver biopsy can detect distant metastasis. A hormonal receptor assay done on the tumor can determine if the tumor is estrogen- or progesterone-dependent. (This test guides decisions to use therapy that blocks the action of the estrogen hormone that supports tumor growth.)
Much controversy exists over breast cancer treatments. In choosing therapy, the patient and physician should consider the stage of the disease, the woman’s age and menopausal status, and the disfiguring effects of the surgery. Treatment for breast cancer may include one or any combination of the following.
With breast cancer, surgery involves either lumpectomy or mastectomy. A lumpectomy may be done on an outpatient basis and may be the only surgery needed, especially if the tumor is small and there’s no evidence of axillary node involvement. Radiation therapy is often combined with this surgery.
A two-stage procedure, in which the surgeon removes the lump, confirms that it’s malignant, and discusses treatment options with the patient, is desirable because it allows the patient to participate in her treatment plan. Sometimes, if the tumor is diagnosed as malignant, such planning can be done before surgery. In lumpectomy and dissection of the axillary lymph nodes, the tumor and the axillary lymph nodes are removed, leaving the breast intact.
A simple mastectomy removes the breast but not the lymph nodes or pectoral muscles. A modified radical mastectomy removes the breast and the axillary lymph nodes. A radical mastectomy, the performance of which has declined, removes the breast, the pectoralis major and minor, and the axillary lymph nodes.
After a mastectomy, reconstructive surgery can create a breast mound if the patient desires it and doesn’t have evidence of advanced disease.
Chemotherapy, tamoxifen, and peripheral stem cell therapy
Various cytotoxic drug combinations are used as either adjuvant or primary therapy, depending on several factors, including staging and estrogen receptor status. The most commonly used antineoplastics are cyclophosphamide, fluorouracil, methotrexate, doxorubicin, vincristine, paclitaxel, and prednisone. A common drug combination used in both premenopausal and postmenopausal women is cyclophosphamide, methotrexate, and fluorouracil.
Tamoxifen, an estrogen antagonist, is the adjuvant treatment of choice for postmenopausal patients with positive estrogen receptor status.
Peripheral stem cell therapy may be used for patients with advanced breast cancer.
Primary radiation therapy
Used before or after tumor removal, primary radiation therapy is effective for small tumors in early stages with no evidence of distant metastasis; it’s also used to prevent or treat local recurrence. Presurgical radiation to the breast in patients with inflammatory breast cancer helps make tumors more surgically manageable.
Other drug therapy
Breast cancer patients may also receive estrogen, progesterone, androgen, or antiandrogen aminoglutethimide therapy. The success of these drug therapies with growing evidence that breast cancer is a systemic, not local, disease has led to a decline in ablative surgery.

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