Grant: Project Grant

As the Canadian population is aging, so too is the average age of breast cancer (BC) diagnosis. In addition, the average size of newly diagnosed breast tumors continues to fall, leading to improved patient prognosis. Current international guidelines recommend endocrine therapy (ET) for all hormone receptor-positive (HR+) early-stage BC treated with surgery. However, these treatment recommendations are based on studies performed decades ago in which older patients were either excluded or present in very small numbers. For older patients, it is unclear if the benefits of ET in terms of reduced risk of recurrence outweigh the risks. This is because older patients are at an increased risk of treatment side effects that negatively affects their quality of life while at the same time their risk of death from other non-cancer causes is much higher. Quite simply, we are faced with an increasing number of patients for whom it is not clear if the benefits of ET outweigh the risks. We recently completed a pilot study that randomized older patients with low-risk BC to receive ET or not. The study opened in 7 centres across Canada and 108 patients participated. Considering the patients and health care providers' great interest, we proposed a large, randomized trial to definitively evaluate the risks and benefits of ET for older patients with low-risk BC. This type of study is key in optimizing care for older patients. If this study confirms that the risks of ET outweigh the benefits, ET will no longer be recommended for this population. This will improve patient quality of life by avoiding side effects from unnecessary treatment.