Concurrent chemo-endocrine treatment for early hormone-positive breast cancer: a no-go???

Endocrine therapy is one of the cornerstones of early breast cancer treatment. While this medication could be initiated on the day of diagnosis, it is often postponed until after completion of surgery, radiotherapy, and chemotherapy. This practice is based on preclinical data suggesting an antagonistic effect between endocrine therapy and cytostatic agents, and on the interpretation of clinical trials comparing concurrent versus sequential use of tamoxifen and chemotherapy. These clinical trials, however, have never shown a statistically significant difference in overall survival or disease-free survival and focused on tamoxifen rather than aromatase inhibitors. Nevertheless, sequentially administered endocrine and chemotherapy have become standard of care worldwide.

We performed a literature review and conclude that concurrent endocrine chemotherapy is at least as effective as sequential treatment. In fact, higher response rates have been observed in trials with aromatase inhibitors rather than tamoxifen in a neoadjuvant setting.

We encourage breast cancer oncologists to re-consider concurrent endocrine chemotherapy as a possible treatment strategy enabling early start of potentially curative endocrine treatment.