Effects of adjuvant tamoxifen therapy on the incidence of secondary cancer: results from a randomized trial with long term follow-up
2014 (English)Manuscript (preprint) (Other academic)
Tamoxifen is a well-established endocrine treatment for breast cancer. We here present results with respect to second primary cancer from a large randomized trial of 5 and 2 years of adjuvant tamoxifen. Breast cancer distant recurrence and mortality are also reported.
Our study included 4128 postmenopausal patients with early stage breast cancer who were alive and free of breast cancer recurrence after 2 years of tamoxifen therapy. They were randomized to receive three more years of therapy or stop tamoxifen. In the comparison of 5 years versus 2 years of postoperative tamoxifen treatment hazard ratios were estimated using Cox regression for different follow-up periods defined as: During treatment (2-5 years) and after treatment (5-10 years, 10-15 years, > 5 years, > 10 years and > 15 years).
In the five years group the incidence of lung cancer was halved (hazard ratio [HR], 0.45, 95% confidence interval [95% CI], 0.27-0.77 [P = .0038]), and lung cancer mortality was decreased. An increased risk was observed for endometrial cancer (HR, 1.83; 95% CI, 1.19-2.81 [P = .0059]), but this risk appeared to decrease over time. The risk of contralateral breast cancer was decreased (HR, 0.73; 95% CI, 0.56-0.96 [P = .022]), also in the period after treatment stopped. In the five years group, the risk of distant recurrence was decreased, and statistically significant reductions were observed both during treatment and in the five year period after treatment stopped. The breast cancer mortality was reduced, especially during the post-treatment phase.
In this randomized study, tamoxifen substantially reduces the risk of new cancer both in contralateral breast and in lung up to 10 years after treatment stopped.
Place, publisher, year, edition, pages
breast cancer, tamoxifen, adjuvant treatment, second primary cancer, lung cancer
Public Health, Global Health, Social Medicine and Epidemiology Cancer and Oncology
IdentifiersURN: urn:nbn:se:liu:diva-112285OAI: oai:DiVA.org:liu-112285DiVA: diva2:765171