PATIENT 1: A PERSONAL AND FAMILY HISTORY OF BREAST CANCER
A 55-year-old Ashkenazi Jewish woman presents to your clinic for her annual physical. She reports that she had been diagnosed with breast cancer 10 years ago and that it had been treated with lumpectomy. You recall that Ashkenazi Jewish ethnicity and a diagnosis of breast cancer before age 50 are red flags for a hereditary cancer syndrome, and you ask about her family history of cancer. She reports that her mother was diagnosed with breast cancer in her 60s. The patient wants to know if her daughter should start breast cancer screening.
What do you do next?
Facing increasing demands and a plethora of information to be discussed in a short time, primary care physicians may find it challenging to inform patients about the possibility of a hereditary cancer syndrome, to assess the risk, to organize genetic testing if appropriate, and to counsel patients about their management options. As our knowledge of the genetics of breast cancer continues to expand, this information will become more detailed and complex.
Nevertheless, primary care physicians can help identify patients who may have a syndrome of inherited cancer predisposition or whose family history raises concern for familial breast cancer. Patients in both groups may be candidates for genetic risk assessment, for special management options for women at high risk, or for both.
This article provides an overview of inherited conditions associated with higher breast cancer risk, and guidelines to help physicians recognize patients in their own practice for whom a genetics referral may be appropriate.
BREAST CANCER IS COMPLEX AND HETEROGENEOUS
Breast cancer is the second-leading cause of cancer deaths in women. According to the American Cancer Society, an estimated 234,340 new cases of breast cancer are expected to be diagnosed in women in the United States in 2013, and about 2,240 new cases are expected in men; 39,620 women and 410 men are expected to die of it.1
Breast cancer is a complex and heterogeneous disease, influenced by many factors, of which female sex and increasing age are the most significant. Modifiable risk factors include obesity, use of combined hormone replacement therapy, and physical inactivity. Other risk factors include dense breast tissue, having had a breast biopsy in the past, the finding of atypical hyperplasia on biopsy, a history of high-dose chest radiation, and reproductive factors that include early menarche, late menopause, nulliparity, and birth of first child after age 30.
After female sex and age, family history of the disease is the most significant risk factor for breast cancer.2 If a woman has a first-degree relative (mother, sister, daughter) with breast cancer, her risk is 1.8 times higher, and if she has a second-degree relative (aunt, grandmother) with breast cancer, her risk is 1.3 times higher.3
Hereditary cancer predisposition syndromes account for 5% to 10% of cases of breast cancer. These are caused by a germline mutation in a highly penetrant gene that considerably increases the risk of malignancies of the breast and other tissues. These conditions are inherited in an autosomal-dominant fashion, with age of onset tending to be significantly—several decades—younger than the median age of onset in the general population. The most common of these is hereditary breast and ovarian cancer syndrome, caused by germline mutations of the BRCA1 or BRCA2 gene.
Familial breast cancers account for 15% to 20% of cases. Here, the women who develop breast cancer have multiple family members who are also affected but without an obvious inheritance pattern, and the age of onset is similar to that in the general population.4
Sporadic forms of breast cancer account for the remaining 70% to 80% of cases. Their development can be attributed mainly to nonhereditary causes, such as the environmental and personal risk factors listed above. In general, sporadic forms of breast cancer occur at older ages, with no particular inheritance pattern and with frequency of occurrence in a family comparable to that in the general population.
IS A GENETICS CONSULTATION NEEDED?
In the case described above, the primary care physician gathered basic information about the patient’s cancer-related personal and family history. Asking a few key questions (Table 1)5,6 can help physicians understand two important things: whether a more detailed assessment of genetic risk and counseling by a genetics professional are indicated, and whether the patient would benefit from additional cancer screening and prevention.
Table 2 summarizes the National Comprehensive Cancer Network’s recommendations for cancer genetics consultation.5 These red flags for a hereditary breast cancer syndrome can help primary care providers identify patients for whom a cancer genetics referral is appropriate. Of note: the maternal and paternal family histories are equally important.
Because our patient was diagnosed with breast cancer before age 50 and is of Ashkenazi Jewish ethnicity, she meets these criteria and warrants a cancer genetics consultation.