Influence on quality of life of chemotherapy scheduling for patients with advanced HER2-negative breast cancer

Abstract

Background: The phase III Stop&Go study randomized patients with advanced breast cancer to two times four intermittent cycles or to eight continuous cycles of first- and second-line chemotherapy, yielding inferior overall survival (OS) with intermittent scheduling. Here we report on the prospectively planned quality of life (QoL) analyses. Methods: QoL was measured by RAND-36 questionnaires every 12 weeks during study treatment and follow-up. Physical and mental component scores were calculated and presented as T-scores with a mean of 50 and a standard deviation (SD) of 10 for the normal population, with higher scores representing better QoL. All patients who responded to baseline questionnaires with sufficient valid data were included. The primary objective was to describe the course of physical and mental QoL for both treatment arms, and to estimate differences in changes from baseline in physical and mental QoL between arms. These differences were estimated longitudinally with multilevel linear regression analyses with a follow up period of 30 months. An effect size of 0.5 SD (5 points) was considered clinically meaningful. Results: A total of 398 patients were included with a median follow-up of 11.3 months (IQR 5.6 - 22.2). Mean baseline scores were 37.9 and 38.3 for physical, and 44.7 and 42.5 for mental QoL for intermittent and continuous treatment respectively. Physical QoL declined linearly in the intermittent arm causing a clinically meaningful difference of 5.68 points at 24 months (p<0.001), while scores in the continuous arm stabilized after a decline of ±3.5 points at 12 months. Conversely, mental QoL was fairly stable and even improved by 1.86 (p=0.012) and 2.53 points (p=0.001) at 12 months for intermittent and continuous treatment. When comparing the arms for both components in changes from baseline, the maximum differences were 3.11 points (p=0.069) for physical and 3.32 points (p=0.057) for mental scores, both measured at 30 months and in favor of continuous treatment. Conclusions: Intermittent chemotherapy was less effective and showed a trend for worse impact on QoL compared to continuous chemotherapy in advanced breast cancer.