Breast cancer is a disease of epithelial cells that line the ducts of the breast. Malignancies of the breast are some of the most common cancers in women (aside from skin cancer) and are responsible for up to one-third of all cancers in women. Mortality because of the cancer is on the decline in the United States due to better detection and treatment. Breast cancer is a clonal disease, meaning that a single transformed cell that eventually expresses full malignant potential causes it. Therefore, it may exist for a long period before it becomes invasive and metastatic (Harrisons, 2008, p.563)
The major risk factors for acquiring breast cancer are genetic and hormonal. Sporadic cases are thought to come about due to abnormal hormonal exposure and familial cases are thought to occur due to genetic mutations (Robbins, 2009, p. 1077). The vast majority of cases occur in women, but a few cases occur in men. Cancers can be divided into two groups, Estrogen Receptor Positive and Estrogen Receptor Negative. The two groups have different etiology, treatment, and prognosis. Incidence peaks between the ages of 75-80, women who reach menarche before the age of 11 have a 20% higher risk of getting cancer, and women who give birth before the age of 20 have half the rates of women aged more than 35 at the time of their first birth (Robbins, 2009, p. 1076). Mutations of the BRCA1 and BRCA2 gene account for the majority of cancers attributable to a single mutation. BRCA1 is also linked to ovarian carcinoma and BRCA2 is linked to male breast cancer. Carriers of both the mutations have higher rates of other epithelial call cancers.
A mass in the breast (or a lumpiness), nipple discharge, and breast pain are the most common symptoms associated with breast cancer. Mammography is the radiological examination of the breast and was introduced in the 1980s as a way to screen the breasts for disease. The examination can show densities and calcifications. Densities are more likely to be cancerous in women over forty years old. Calcifications are associated with Ductal Carcinoma in situ, and are relatively uncommon (Robbins, 2009, p. 1068).
Diagnosis of breast cancer is almost always done by biopsy of a nodule that was detected either by mammogram or through palpation (Harrisons, 2008, p.564). Women are encouraged to self-examine their breasts, however, some studies indicate that self-examination does not alter survival and may lead to increased unnecessary mammography. However, given the safety of self-examination, a responsible physician will still encourage his female patients to do it (Harrisons, 2008, p.564). The breast must be inspected under good light for any retractions or skin changes, the nipples and areola need to be adequately inspected for changes, and the physician should try and provoke a nipple discharge. Regional lymph nodes must also be palpated and measured. Lesions that are hard, irregular, fixed, and painless are more likely to be cancerous, however, physical examination alone cannot rule out malignancies, and likewise, lesions with negative mammograms can also not rule out malignant disease (Harrisons, 2008, p.564). Annual mammography of women over the age of fifty means a 25-30% decrease in chance of dying from breast cancer (Harrisons, 2008, p.565). Another useful tool for detecting breast cancer and staging the disease, as well as guiding therapy is Circulating Tumor Cell (CTC) analysis. Circulating tumor cells occur in during metastasis and represent fragments of the tumor breaking off into the blood stream and going to the rest of the body (Alemar, 2013). Furthermore, CTC can also be used to measure disease status and the progress made in treating the disease.
Treatment of the breast cancer is dependent on the stage of the cancer and the type of tumor that is present. Some women will opt for breast-conserving therapies, while others will prefer that a mastectomy be performed and the diseased breast be removed all together. Breast conserving treatments include a lumpectomy with or without follow-up radiation of the breast. Irradiation after a lumpectomy greatly reduces the chance of a recurrence of the breast cancer (Harrisons, 2008, p.566). However, if the primary tumor is larger than 5cm, or involves the areola and nipple, or involves multiple quadrants of the breast, for women with collagen-vascular disease, or for women without access to radiation therapy, or simply don’t have the motivation for breast conservation, a complete mastectomy is recommended. Likewise, treatment is also dependent on the age of the patient, and includes chemotherapeutic agents and anti-endocrine drugs, such as tamoxifen and trastuzumab (Harrisons, 2008, p.568). Another drug that has been tried in regards to breast cancer is Eribulin. Eribulin has anti-proliferative effects by inhibiting the microtubules of cells and thus not allowing growth (Shablak, 2013). In a trial conducted by Shablak, 32 patients received the drug in weekly doses, and 21 received a dose every three weeks. Effects were confirmed in both the studies and disease stabilization was achieved in a substantial number of the patients in both groups. Eribulin was ultimately shown to be tolerable and had a good response rate. The trial results were good enough to begin stage III clinical trials (Shablak, 2013).
Prognosis depends on the tumor stage; the size of the tumor, whether it has expanded to lymph nodes around the primary site, and metastatic occurrences to other parts of the body. For instance, in women with a stage 0 tumor, that is, no lymph node involvement and no metastases, the five year survival rate is 99%. On the other end of the scale, a woman with stage IV cancer, meaning there is extensive metastasis and lymph node involvement has a 5 year survival rate of 14%. Histological and molecular changes in the tumor cells also may provide prognostic information. For instance, tumors that express the HER-2/neu gene have a worse prognosis than tumors that do not. However, modern analysis has allowed for specific therapies based on the expression of particular genes in tumors and that has had a positive effect on the prognosis of all tumors (Harrisons, 2008, p.567).
In sum, Breast Cancer is a disease that usually affects women most commonly over the age of 50. The etiology is multi-factorial and comes from both the environment and genetics. The diagnosis is relatively simply made by a self-breast examination, palpation, mammogram, and a biopsy should anything be discovered. Both treatment and prognosis are dependent on the type of tumor present and the staging of the tumor. Most commonly, surgical treatment is employed which is either a lumpectomy or a mastectomy. With increased use of imaging studies and increasing resolutions, we are able to detect smaller masses earlier in the course of the disease and excise them by more simple procedures and increase survival for the disease. An early-detected tumor that is smaller than 2cm and has not metastasized anywhere and does not involve lymph nodes has an excellent prognosis, and 99% of the patients will still be cancer free after five years after a simple relatively non-invasive procedure. On the other end of the scale, a tumor that is large, has expanded to lymph nodes, and metastasized to other parts of the body hematologically, has a 5 year survival rate of only 14%. Regular doctor checkups and vigilance regarding the state of your body is key to detection and ultimately survival.
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