Factors associated with weight gain in pre- and post-menopausal women receiving adjuvant endocrine therapy for breast cancer.

Purpose: Weight gain after breast cancer poses health risks. We aimed to identify factors associated with weight gain during adjuvant endocrine therapy (AET).

Methods: Women initiating AET enrolled in a prospective cohort. Participants completed FACT-ES plus PROMIS pain interference, depression, anxiety, fatigue, sleep disturbance and physical function measures at baseline, 3, 6, 12, 24, 36, 48 and 60 months. Treatment-emergent symptoms were defined as changes in scores in the direction indicative of worsening symptoms that exceeded the minimal important difference at 3 and/or 6 months compared to baseline. We used logistic regression to evaluate associations of clinicodemographic features and treatment-emergent symptoms with clinically significant weight gain over 60 months (defined as ≥ 5% compared to baseline) in pre- and post-menopausal participants.

Results: Of 309 participants, 99 (32%) were pre-menopausal. The 60 months cumulative incidence of clinically significant weight gain was greater in pre- than post-menopausal participants (67% vs 43%, p < 0.001). Among pre-menopausal participants, treatment-emergent pain interference (OR 2.49), aromatase inhibitor receipt (OR 2.8), mastectomy, (OR 2.06) and White race (OR 7.13) were associated with weight gain. Among post-menopausal participants, treatment-emergent endocrine symptoms (OR 2.86), higher stage (OR 2.25) and White race (OR 2.29) were associated with weight gain while treatment-emergent physical function decline (OR 0.30) was associated with lower likelihood of weight gain.

Conclusions: Weight gain during AET is common, especially for pre-menopausal women. Clinicodemographic features and early treatment-emergent symptoms may identify at risk individuals.

Implications For Cancer Survivors: Patients at risk for weight gain can be identified early during AET.

Gov Identifier: NCT01937052, registered September 3, 2013.