Chemo ‘Not Enough’ for Very Young ER+ Breast Cancer Patients

ATLANTA—In an attempt to find ways to improve the prognosis for breast cancer in very young women, the International Breast Cancer Study Group (IBCSG) looked back at outcomes in 3,700 premenopausal and perimenopau-sal patients who had been treated in four randomized controlled trials between 1978 and 1993. Results of that analysis were presented at a poster session at the 35th annual meeting of the American Society of Clinical Oncology (ASCO).

Reporting for the IBCSG, Stefan Aebi, MD, of the University of Bern, Switzerland, said this analysis showed that breast cancer patients under age 35 may need endocrine therapy as well as cytotoxic chemotherapy. The study included 314 patients under age 35, and 3,386 patients age 35 or older. Patients had been treated with various schedules of adjuvant cyclophosphamide, methotrexate, and fluorouracil (CMF) with or without low-dose prednisone.

Dr. Aebi reported that relapse and death occurred earlier and more often in patients under 35 than in those over 35. Ten-year disease-free survival was 35% in those under age 35 vs 47% in older women (p < .007)(see Table).

Ten-year overall survival was 49% in those under 35 vs 62% in those over 35 (p < .001). Ten-year overall survival in young women with estrogen-receptor (ER)-positive tumors was significantly worse than in young women with ER-negative tumors (39% vs 52%). In patients over age 35, prognosis was more favorable among the patients with ER-positive tumors (10-year overall survival, 63% vs 58%). If chemotherapy did not induce amenorrhea, 10-year overall survival was significantly reduced in women under age 35, but disease-free survival was not greatly affected.

“Young patients with ER-positive tumors had a particularly unfavorable prognosis if the chemotherapy did not induce amenorrhea,” Dr. Aebi said. “Patients under 35 with ER-positive breast cancer need adjuvant endocrine treatment.” The researchers concluded, “In very young (less than age 35) premenopausal breast cancer patients treated with adjuvant CMF chemotherapy, the risk of relapse and death is substantially higher than among older premenopausal patients.”

In this younger patient population, those with ER-negative tumors fared better than those with ER-positive tumors. “This may be due in part to an insufficient endocrine effect of chemotherapy in the youngest patients,” Dr. Aebi said.