Changes in weight, physical and psychosocial patient -reported outcomes among obese women receiving treatment for early -stage breast cancer: A nationwide clinical study

{Background: Evidence on how weight loss correlates to health -related quality -of -life (HRQOL) among obese breast cancer (BC) patients is limited. We aimed to evaluate associations between weight changes and HRQOL. Methods: We included 993 obese women with stage I -II -III BC from CANTO, a multicenter, prospective cohort collecting longitudinal, objectively -assessed anthropometric measures and HRQOL data (NCT01993498). Associations between weight changes (+/- 5% between diagnosis and post -treatment [shortly after completion of surgery, adjuvant chemo- or radiation -therapy]) and patient -reported HRQOL (EORTC QLQ-C30/B23) were comprehensively evaluated. Changes in HRQOL and odds of severely impaired HRQOL were assessed using multivariable generalized estimating equations and lo- gistic regression, respectively. Results: 14.1% women gained weight, 67.3% remained stable and 18.6% lost weight. Signi ficant decreases in functional status and exacerbation of symptoms were observed overall post -treatment. Compared to gaining weight or remaining stable, obese women who lost weight experienced less of a decline in HRQOL, reporting better physical function (mean change [95%CI] for gain, stability and loss: -12.9 [-16.5,-9.3], -6.9 [-8.2,-5.5] and -6.2 [-8.7,-3.7]; p(interaction[weight-change-by-time]) = 0.006), less dyspnea (+18.9 [+12.3,+25.6], +9.2 [+6.5,+11.9] and +3.2 [-1.0,+7.3]; p interaction = 0.0003), and fewer breast symptoms (+22.1 [+16.8,+27.3], +18.0 [+15.7,+20.3] and +13.4 [+9.0,+17.2]; p(interaction) = 0.044). Weight loss was also signi ficantly associated with reduced odds of severe pain compared with weight gain (OR [95%CI] = 0.51 [0.31-0.86]