LAUSR

Breast cancer (BC) is a common type of cancer in women. Advances in therapy options have resulted in higher overall survival rates but side effects of cancer treatment are increasingly in the spotlight. The beneficial effects of anti‐oestrogen therapy with tamoxifen and letrozole in the prevention of BC recurrence are well documented. While the most common side‐effects of this therapy are well‐defined, less is known about its effects on thyroid function. In women treated for early BC, an average of 1–5 kg weight gain has been observed after treatment with chemotherapy/anti‐oestrogens. We aim to evaluate the current knowledge on the side effects of tamoxifen and letrozole treatments on thyroid function, followed by its potential influence on the observed weight gain.