ORLANDO--Breast-conserving therapy appears to be a viable treatment option for breast cancer patients with a family history of breast cancer, Elizabeth Chabner, MD, said at the annual meeting of the American Society for Therapeutic Radiation and Oncology (ASTRO).
Her study showed that women with a family history suggestive of a genetic susceptibility to breast cancer have a different pattern of failure after breast-conserving treatment and radiotherapy, with a higher rate of contralateral breast cancer, compared with those with no family history. However, there is no increased risk of local or distant failure.
Dr. Chabner, of Harvards Joint Center for Radiation Therapy and Brigham Young Womens Hospital, and her colleagues from the Dana-Farber Cancer Institute, Beth Israel Deaconess Medical Center, and Harvard Medical School, looked at 205 patients all under age 36 at the time of diagnosis of stage I or II invasive breast cancer.
All patients were treated with breast-conserving surgery plus radiotherapy between 1968 and 1986, with a median follow-up of 12.8 years.
Of the 205 patients, 201 were evaluable for family history as taken from their medical records, and 29 (15%) had a positive family history--a mother or sister diagnosed before the age of 50 with breast cancer or diagnosed with ovarian cancer at any age.
The 5-year crude outcome results by site of first failure were similar in both groups with the exception of contralateral breast cancer, which was only 3% in those with a negative family history versus 14% in those patients with a positive family history.
A multiple variable analysis was performed factoring in the presence of lymphatic vascular invasion, tumor size less than 1.5 cm, more than four positive nodes, estrogen-receptor status, and the presence of necrosis.
According to this analysis, patients with a positive family history had an elevated risk for contralateral breast cancer versus no evidence of disease (NED) of 5.7; and a reduced risk for local regional failure versus NED (0.2) and distant regional failure versus NED (0.4).
There were no significant differences between the two groups in cosmetic outcome and treatment toxicity.
Some of the limitations of the study, Dr. Chabner said, were that genetic susceptibility was not tested directly, the study sample size was small, and there was a potential for misclassification due to lack of histologic confirmation of cancers in mothers and sisters. However, she thinks the study shows that family history can serve as a proxy for genetic testing.
"We conclude that breast-conserving therapy is a safe alternative treatment," Dr. Chabner said. "You have to watch the opposite breast, but we would do that with a woman who did not have a family history who had a lumpectomy or a mastectomy."
Dr. Chabner said that the Joint Center will be conducting a prospective study comparing treatment outcomes among patients with and without an inherited susceptibility to breast cancer by genetic testing.