Abstract P4-09-12: The Effect of Age on Breast Cancer Outcomes in Women with Her-2 Positive Breast Cancer: Results from the HERA Trial

Background: Previous research has suggested that young age at diagnosis is an independent risk factor for breast cancer recurrence and death. However, young women are more likely to develop more aggressive subtypes of breast cancer and no prior studies have adequately controlled for Her-2/neu status or anti-Her-2 treatment. We sought to evaluate whether age is a prognostic factor in the HERA trial, which is a large randomized phase III trial of women with Her-2 positive early stage breast cancer who were randomized to receive trastuzumab (for one or two years) or observation following (neo)-adjuvant chemotherapy. Methods: We used 2 year median follow-up data from the HERA trial and conducted Cox proportional hazards models. Age was dichotomized at ≥40 years versus > 41 years to evaluate its prognostic effect on outcomes in women who received trastuzumab and those who did not. Only patients included in the 1-year trastuzumab and observation arms were included in the present analysis. Results: Of the 1703 women randomized to one-year of trastuzumab and 1698 to observation, 722 (21%) were age 40 or younger at study entry. Younger women were more likely to have node negative (33% vs 37%), estrogen receptor (ER)-negative (56 % vs 49%), and progesterone receptor (PR)-positive disease (41% vs 32%). In separate Cox models controlling for T and N stage, grade, ER and PR status, chemotherapy, endocrine therapy, and menopausal status at randomization, disease-free survival (DFS) hazard ratios were consistent for women ≥40 years compared with > 41 years old patients, regardless of whether they were assigned to observation or to receive trastuzumab. DFS were as follow: observation group: HR (younger/older) = 1.09, p-value = 0.62; trastuzumab group: HR (younger/older) = 1.05, p-value = 0.84. There was no statistically significant interaction between age and treatment (p=0.94). Conclusions: In women with early stage Her-2/neu positive breast cancer in a large RCT, age was not an independent predictor of risk of early recurrence. Future research to investigate whether age is a predictor of later risk of recurrence or is a predictor among women with other tumor subtypes is warranted. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-09-12.