Physical and functional well-being in women with breast cancer taking gabapentin for hot flashes.

Abstract

9141 Background: Hot flashes reduce quality of life (QOL) in women with breast cancer. In a randomized, double-blind, placebo-controlled trial of gabapentin for hot flashes, 900 mg of the drug was found to reduce hot flashes in women with breast cancer; however, their QOL of has not been studied. We conducted secondary analyses to study two domains of QOL: physical (PWB) and functional well-being (FWB) in women in this trial. Methods: A nationwide sample of women with breast cancer and hot flashes ≥ 2/day was studied at baseline (T1), 4 weeks (T2), and 8 weeks (T3) of treatment with gabapentin 300mg/day (G300) and 900mg/day (G900) in divided doses, and a matching placebo (PL). PWB and FWB were assessed via subscales of the Functional Assessment of Cancer Therapy-Breast. Linear mixed model analyses of PWB and FWB were conducted, adjusted for demographic and treatment variables. Results: The mean age of women (N=384) was 54.9 years ± 8.07 (range: 31-81, 72% >50 years); 76% were married; 71% had more than high school education; 95% were Caucasian and 3% African-American; 10% were undergoing chemotherapy, and 9% radiotherapy (RT). PWB showed significant time effect (p<.0001) and interaction of time and treatment (p<.0001). There was an improvement in PWB in the G300 by T2 with no change at T3, while the improvement in PL and G900 was more modest at T2 and continued at T3 (PL - T1 20.7, T2 21.2, T3 21.6; G300 - T1 20.9, T2 22.2, T3 22.2; and G900 - T1 21.2, T2 21.5, T3 21.7). FWB also showed a significant time effect (p=.001) and interaction of time and treatment (p<.002). FWB in G300 improved by T2, with no additional improvement at T3; it was unchanged in G900 at T2 with a slight reduction at T3; PL showed a modest improvement at T2 followed by a modest worsening at T3 (PL - T1 17.8, T2 18.1, T3 17.9; G300 - T1 17.9, T2 18.6, T3 18.6; G900 - T1 18.6, T2 18.6, T3 18.5). Conclusions: As reported previously, G900 is effective in reducing hot flashes. In this analysis, however, PWB and FWB showed different patterns of change over time between the two gabapentin and placebo groups with G900 showing minimal effects on PWB and FWB. Future trials to further study the changes in physical and functional well-being of women with breast cancer taking gabapentin for hot flashes are needed.