BREAST CANCER IN PRIMARY CARE - University of Chicago



BREAST CANCER

Melissa Pradhan, M.D. and Julie Rosenbaum, M.D.

WEEK 19

Learning Objectives:

1. Be able to use the Gail model to calculate a woman’s five-year and lifetime risk of breast cancer

2. Know how to make treatment recommendations based on calculated breast cancer risk

3. Know when the use of tamoxifen is indicated and contraindicated, and the side effects of tamoxifen

4. Discuss recommended follow-up for breast cancer survivors

5. Recognize the indications for genetic testing for BRCA1 and BRCA2, and know where to refer patients for testing

6. Recognize complications of treatment for breast cancer

CASE ONE:

A 48-year-old Caucasian woman with no significant medical history presents to your office for a routine physical. Her family history is significant for breast cancer in her mother at age 60. Her menstrual periods began at age 12, she has never had any breast biopsies, she has never had children, and she is premenopausal.

Questions:

1. What is the value of the Gail model to the primary care clinician, and what are its limitations?

The model can be used to stratify patients into two risk categories. If a woman’s five-year risk is determined to be less than 1.66%, then her risk for developing breast cancer is low and routine screening can be continued. If a woman’s five-year risk is determined to be above 1.66%, then she is classified as high risk and her options include increased surveillance, chemoprevention with tamoxifen, and prophylactic mastectomy. The main limitation of the Gail model is that it can underestimate cancer risk because it does not take into account risk from genetic mutations such as BRCA1 or BRCA2.

2. What is this woman’s five-year risk of developing breast cancer, according to the Gail model?

Note to preceptors: It might be beneficial to walk through the calculation with the group. According to the model, the patient’s five-year risk of developing invasive breast cancer is 1.8%, compared to 1.2% for a woman of the same age and race with average risk factors. Her lifetime risk is 17.3%, compared to 11.5% for a woman of the same age and race with average risk factors. (A computerized tool is available on the Internet at . Based upon the number of the risk factors present, the tool will calculate a woman’s five-year and lifetime risk compared to the average for her age and race).

3. Would you recommend tamoxifen for this patient? Why or why not?

The Breast Cancer Prevention Trial (BCPT) addressed the issue of the use of tamoxifen for prevention of breast cancer in high-risk women. The criterion for participation in the trial was a five-year Gail index of at least 1.66% or a history of lobular carcinoma in situ. 13,388 women were enrolled in this double blind trial; 6,707 were randomized to a placebo group and 6,681 to a treatment group who received tamoxifen 20 mg daily. The trial was to go on for five years, but at 4.5 years it was terminated because the beneficial effects of tamoxifen were found to be so highly significant that all women in the placebo group were offered tamoxifen therapy. Tamoxifen reduced by approximately 50% the incidence of both noninvasive and invasive breast cancers. The risk reduction increased with age. Most significantly, in patients with previous atypical ductal hyperplasia, an 86% reduction was seen in cases of invasive breast cancer.

Tamoxifen is currently the only medical therapy recommended for breast cancer prevention. However, an increased incidence of uterine sarcoma has been noted in women taking tamoxifen, due to its proestrogenic effects on the endometrium. The risk is higher in postmenopausal women, obese women, and women who have had HRT in the past. Among women who take tamoxifen, endometrial cancer develops in 0.5-1.0% of women, which is three times higher than the endometrial cancer rate among women taking placebo. Contraindications to tamoxifen use are as follows:

Five-year Gail index ................
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