Genetic Characteristics and Risk Factors
Several well-established factors have been associated with an increased risk of breast cancer, including family history, nulliparity, early menarche, advanced age, and a personal history of breast cancer (in situ or invasive).
Age-specific risk estimates are available to help counsel and design screening strategies for women with a family history of breast cancer.[2,3] Of all women with breast cancer, 5% to 10% may have a germ-line mutation of the genes BRCA1 and BRCA2. Specific mutations of BRCA1 and BRCA2 are more common in women of Jewish ancestry. The estimated lifetime risk of developing breast cancer for women with BRCA1 and BRCA2mutations is 40% to 85%. Carriers with a history of breast cancer have an increased risk of contralateral disease that may be as great as 5% per year. Ma le carriers of BRCA2 mutations are also at increased risk for breast cancer.
Mutations in either the BRCA1 or BRCA2 gene also confer an increased risk of ovarian cancer.[7-9] In addition, mutation carriers may be at increased risk of other primary cancers.[7,9] Genetic testing is available to detect mutations in members of high-risk families.[10-14] Such individuals should first be referred for counseling. (Refer to the PDQ summaries on Genetics of Breast and Ovarian Cancer; Breast Cancer Prevention; and Breast Cancer Screening for more information.)
Clinical trials have established that screening with mammography, with or without clinical breast examination, may decrease breast cancer mortality. (Refer to the PDQ summary on Breast Cancer Screening for more information.)
Patient management following initial suspicion of breast cancer generally includes confirmation of the diagnosis, evaluation of stage of disease, and selection of therapy. At the time the tumor tissue is surgically removed, estrogen receptor (ER) and progesterone receptor (PR) status should be determined.
Prognostic and Predictive Factors
Breast cancer is commonly treated by various combinations of surgery, radiation therapy, chemotherapy, and hormone therapy. Prognosis and selection of therapy may be influenced by the following clinical and pathology features (based on conventional histology and immunohistochemistry):
- The age and menopausal status of the patient.
- The stage of the disease.
- The histologic and nuclear grade of the primary tumor.
- The ER and PR status of the tumor.
- Human epidermal growth factor type 2 receptor (HER2/neu) overexpression.
- Proliferative capacity of the tumor (e.g., Ki67).
- Luminal A.
- Luminal B.
- ER and PR status testing.
- HER2/neu receptor status testing.
- Gene profile testing by microarray assay or reverse transcription-polymerase chain reaction (e.g., MammaPrint, Oncotype DX).
Although certain rare inherited mutations, such as those of BRCA1 and BRCA2, predispose women to develop breast cancer, prognostic data on BRCA1/BRCA2 mutation carriers who have developed breast cancer are conflicting; these women are at greater risk of developing contralateral breast cancer. Since criteria for menopausal status vary widely, some studies have substituted age older than 50 years as a surrogate for the postmenopausal state. Breast cancer is classified into a variety of histologic types, some of which have prognostic importance. For example, favorable histologic types include mucinous, medullary, and tubular carcinoma.[19-21]
Pathologically, breast cancer can be a multicentric and bilateral disease. Bilateral disease is somewhat more common in patients with infiltrating lobular carcinoma. Patients who have breast cancer should have bilateral mammography at the time of diagnosis to rule out synchronous disease. The role of magnetic resonance imaging (MRI) in screening and follow-up continues to evolve. Having demonstrated an increased detection rate of mammographically occult disease, the selective use of MRI for additional screening is being used with increased frequency despite the absence of randomized, controlled data. Because only 25% of MRI-positive findings represent malignancy, pathologic confirmation prior to treatment action is recommended. Whether this increased detection rate will translate into improved treatment outcome is unknown.[22-24] When BRCA1/BRCA2 mutation carriers were diagnosed at a young age, the risk of a contralateral breast cancer reached nearly 50% in the ensuing 25 years.[25,26]
Patients should continue to have regular breast physical examinations and mammography to detect either recurrence in the ipsilateral breast in those patients treated with breast-conserving surgery or a second primary cancer in the contralateral breast. The risk of a primary breast cancer in the contralateral breast is approximately 1% per year.[28,29] Patient age younger than 55 years at the time of diagnosis or lobular tumor histology appear to increase this risk to 1.5%. The development of a contralateral breast cancer is associated with an increased risk of distant recurrence.[31,32]
Hormone Replacement Therapy
The use of hormone replacement therapy (HRT) poses a dilemma for the rising numbers of breast cancer survivors, many of whom enter menopause prematurely as a result of therapy. HRT has generally not been used for women with a history of breast cancer because estrogen is a growth factor for most breast cancer cells in the laboratory; however, empiric data on the safety of HRT after breast cancer are limited.[33,34]
Two randomized trials (including Regional Oncologic Center-Hormonal Replacement Therapy After Breast Cancer–Is It Safe [ROC-HABITS]) comparing HRT with no hormonal supplementation have been reported.[35,36] The first trial included 345 evaluable breast cancer patients with menopausal symptoms and was terminated early because of an increased incidence of recurrences and new primaries in the HRT group (hazard ratio [HR] = 3.5; 95% confidence interval [CI], 1.5–7.4).[Level of evidence: 1iiDii] In total, 26 women in the HRT group and 7 in the non-HRT group developed recurrences or new primaries. This study, however, was not double blinded, and it is possible that patients on HRT were monitored more closely. Because of the results of the first trial, the second trial, which was conducted under a joint steering committee with the first, closed prematurely after the enrollment of 378 patients. With a median follow-up of 4.1 years, there were 11 recurrences in the hormone replacement group and 13 recurrences in the patients assigned to no hormone replacement (HR = 0.82; 95% CI, 0.35–1.9).[Level of evidence: 1iiDii] The trials differed in several ways; however, until further data become available, decisions concerning the use of HRT in patients with breast cancer will have to be based on the results of these studies and on inferences from the impact of HRT use on breast cancer risk in other settings. A comprehensive intervention, including education, counseling, and nonhormonal drug therapy, has been shown to reduce menopausal symptoms and to improve sexual functioning in breast cancer survivors.[Level of evidence: 1iiC] (For more information, refer to the PDQ summaries on Fever, Sweats, and Hot Flashes andSexuality and Reproductive Issues.)
For patients who opt for a total mastectomy, reconstructive surgery may be used at the time of the mastectomy (immediate reconstruction) or at some subsequent time (delayed reconstruction).[39-42] Breast contour can be restored by the submuscular insertion of an artificial implant (saline-filled) or a rectus muscle or other flap. If a saline implant is used, a tissue expander can be inserted beneath the pectoral muscle. Saline is injected into the expander to stretch the tissues for a period of weeks or months until the desired volume is obtained. The tissue expander is replaced by a permanent implant. (Visit the FDA’s Web site for more information on breast implants.) Rectus muscle flaps require a considerably more complicated and prolonged operative procedure, and blood transfusions may be required.
Following breast reconstruction, radiation therapy can be delivered to the chest wall and regional nodes either in the adjuvant setting or if local disease recurs. Radiation therapy following reconstruction with a breast prosthesis may affect cosmesis, and the incidence of capsular fibrosis, pain, or the need for implant removal may be increased.
Evidence from randomized trials indicates that periodic follow-up with bone scans, liver sonography, chest x-rays, and blood tests of liver function does not improve survival or quality of life when compared to routine physical examinations.[44-46] Even when these tests permit earlier detection of recurrent disease, patient survival is unaffected. Based on these data, some investigators recommend that acceptable follow-up be limited to physical examination and annual mammography for asymptomatic patients who complete treatment for stage I to stage III breast cancer. The frequency of follow-up and the appropriateness of screening tests after the completion of primary treatment for stage I to stage III breast cancer remain controversial.