Functional decline in older breast cancer survivors treated with and without chemotherapy and non-cancer controls: results from the Hurria Older PatiEnts (HOPE) prospective study

This study aimed to assess whether physical functional decline in older women with early-stage breast cancer is driven by cancer, chemotherapy, or a combination of both. We prospectively sampled three groups of women aged ≥ 65: 444 with early-stage breast cancer receiving chemotherapy (BC Chemo), 98 with early-stage breast cancer not receiving chemotherapy (BC Control), and 100 non-cancer controls (NC Control). Physical function was assessed at two timepoints (T1 [baseline] and T2 [3, 4, or 6 months]) using the Physical Functioning Subscale (PF-10) of the RAND 36-item Short Form. The primary endpoint was the change in PF-10 scores from T1 to T2, analyzed continuously and dichotomously (Yes/No, with "yes" indicating a PF-10 decline > 10 points, i.e., a substantial and clinically meaningful difference). Baseline PF-10 scores were similar across all groups. The BC Chemo group experienced a significant decline at T2, with a median change in PF-10 of -5 (interquartile range [IQR], -20, 0), while BC Control and NC Control groups showed a median change of 0 (IQR, -5, 5; p < 0.001). Over 30