Evaluating the effect on survival of long-term hormone therapy in breast cancer patients

This study examined the impact on survival of more than 5 years of adjuvant hormonal therapy in breast cancer patients.

Some types of breast cancer grow in response to female sex hormones (estrogen and progesterone) via their receptor (a protein found on breast cells). These are called hormone receptor-positive (HR+) breast cancers. Patients who have HR+ breast cancer usually respond to hormone therapy which either reduces the estrogen levels in the body or stops estrogen from getting to the cancer. Tamoxifen (Nolvadex) is a hormone therapy drug that prevents estrogen from binding to its receptor on breast cancer cells, thus stopping the growth of breast cancer.

Previous studies have shown that breast cancer (BC) patients who undergo 5 years of adjuvant (additional to other treatments, usually surgery) tamoxifen therapy have a 30% smaller risk of death and a 40% smaller risk of recurrence (return of the cancer). Some studies have found that adjuvant hormone therapy beyond 5 years, with either tamoxifen or another hormonal therapy, increased survival rates even further. The current research analyzed the results of several previously published studies to determine if hormone therapy for more than 5 years had any benefits in terms of survival in HR+ breast cancer patients.

This research analyzed the results of eight studies, which included a total of 29,138 patients. Half of these patients received tamoxifen for 5 years, and the other half underwent extended therapy with either tamoxifen or another adjuvant hormone therapy drug. The main parameters evaluated were overall survival (the percentage of patients surviving a certain time after the treatment), breast cancer-specific survival or BCSS (defined as the percentage of patients who survived breast cancer after a certain period of time) and recurrence-free survival or RFS (defined as the percentage of patients who have survived for a certain period of time without the cancer returning). Results showed that patients who underwent extended treatment experienced increased survival (risk of mortality was reduced by 11%), an increase in BCSS (risk of breast cancer specific mortality was reduced by 22%), and a 28% reduction in the risk of recurrence.

In summary, adjuvant hormonal therapy beyond 5 years increases survival rates in patients with HR+ breast cancer. 

This was a retrospective study (it looks back at patients who have been treated in the past). These studies are known to have lower statistical power than studies directly testing a hypothesis. Also, this study did not mention any adverse effects to prolonged hormonal therapy. 

Ask your doctor whether prolonging hormonal therapy is appropriate in your situation.