Background: The effect of endocrine therapy with tamoxifen (TMX) on weight gain has been reported in the literature, but the outcomes are still controversial. Moreover, previous treatment options, such as chemotherapy (CT), also include body changes. The focus of this study was to verify the temporal influence of endocrine therapy with TMX on nutritional risk and obesity and its association with CT in breast cancer patients.
Methods: In this cross-sectional study, 84 breast cancer surviving women were evaluated during endocrine therapy with TMX. Anthropometric, biochemical and body composition parameters were measured. A generalized estimating equation (GEE) was used to examine the association between CT and groups of women using TMX categorized by the duration of the treatment (group 1, women using TMX for the first 3 years; group 2, women using TMX between 3 and 4 years and group 3, women using TMX for more than 4 years).
Results: The interaction of CT with duration of TMX use showed a significant effect on Body Mass Index (BMI), waist circumference (WC) and body fat percentage (BFP) (GEE p-value = 0.002, 0.000, 0.000, respectively). Women from group 1 who underwent CT presented higher values of body variables compared to those women from group 2 who also underwent CT (BMI = 29.14 ± 0.93, 26.76 ± 0.85 kg/m2; WC = 94.45 ± 1.96, 91.07 ± 2.44 cm; BFP = 36.36 ± 1.50, 33.43 ± 1.66%, respectively). On the other hand, women from group 1 who did not undergo CT presented lower values of body variables compared to those women from group 2 who also did not undergo CT (BMI = 25.29 ± 0.46, 28.40 ± 0.95 kg/m2; WC = 85.84 ± 0.90, 97.75 ± 0.88 cm; BFP = 30.32 ± 0.43; 42.95 ± 1.03%, respectively).
Conclusions: Women on endocrine therapy with TMX are mostly overweighed and obese, most evidently in women who received CT, and who were at the beginning of treatment. Women that did not undergo CT, despite presenting lower values of body variables in the first 3 years, still deserve special attention because significantly higher values were observed in women between 3 and 4 years of therapy.
Keywords: Body composition; Body weight; Breast neoplasm; Chemotherapy; Endocrine therapy; Tamoxifen.