Being less than 40 years old does not significantly impact survival in women with HER2-positive breast cancer, according to a retrospective analysis of a large, randomized breast cancer study.
"Our finding that age is neither a clear prognostic factor for early recurrence nor a predictive factor for benefit of trastuzumab in women with HER2-positive breast cancer may have important implications for care and future research. Most prior research suggesting that age is an independent prognostic factor has not taken HER2 status into account," noted Dr. Ann H. Partridge and her colleagues.
Younger women are more likely to present with aggressive breast tumors and advanced disease; young age at diagnosis is an independent risk factor for recurrence and death. Few studies have been conducted to evaluate if the finding remains the same among women with HER2-positive (human epidermal growth factor receptor 2–positive) tumors, according to Dr. Partridge, an oncologist at the Dana-Farber Cancer Institute in Boston, and her colleagues.
Dr. Ann Partridge
They performed a retrospective analysis of data from the HERA [Herceptin Adjuvant] study, an open-label, phase III randomized trial that found significantly improved disease-free survival in HER2-positive breast cancer patients who received a year of trastuzumab following adjuvant chemotherapy (N. Engl. J. Med. 2005;353:1659-72).
Among 1,698 women randomly assigned to observation in the trial, there was no significant difference in disease-free survival (HR 1.18; 95% CI, 0.90-1.54) or overall survival (HR 1.01; 95% CI, 0.60-1.69) in women aged 40 years or younger, compared with women over age 40 years (J. Clin. Oncol. 2013;31:2692-8).
This was also true among the 1,703 women randomly assigned to trastuzumab. Disease-free survival (HR 1.11; 95% CI, 0.81-1.51) and overall survival (HR 1.18; 95% CI, 0.66-2.09) were comparable in younger women, compared with those over 40 years of age. Interaction between age group and treatment effect was not statistically significant for either parameter (DFS P = 0.89; OS P = 0.55).
Overall, 722 women (21%) were 40 years of age or younger at study entry.
"Our findings suggest that as breast cancer continues to be better characterized molecularly, and therapies such as trastuzumab are developed to target molecular subtypes, the importance of age with regard to prognosis will continue to diminish, if not disappear," they wrote.
The short follow-up was a limitation of the study. "Future research should investigate whether age is a predictor of later recurrence and evaluate the impact of age within groups with other tumor subtypes," they noted.
Dr. Partridge is a consultant for Genentech, maker of trastuzumab. Another author is an employee of, and holds stock in, Roche, the parent company of Genentech. All but one of the six other investigators have ties to the two companies