Significance of age-associated quality of life in patients with stage IV breast cancer who underwent endocrine therapy in Japan.

Currently, when determining treatment regimens, there is an emphasis on the quality of life (QOL), in addition to treatment efficacy. Especially in hormone receptor-positive breast cancer with distant metastases, unless death is imminent, a common first-line treatment is endocrine therapy, which has fewer side effects. In the present study, the differences in QOL were evaluated based on the age and prognostic indicators of 46 patients with hormone receptor-positive breast cancer with distant metastases (stage IV), who received first-line endocrine therapy at the Osaka City University Hospital (Osaka, Japan) between November 2007 and November 2016. QOL score before and after endocrine therapy was retrospectively analyzed, using the Quality of Life Questionnaire for Cancer Patients Treated with Anti-Cancer Drugs-Breast (QOL-ACD-B). There was no significant association between age and any of the clinicopathological features investigated. However, the QOL score of the elderly patient group was significantly higher compared with that of the younger group in the 'Satisfaction with treatment and coping with disease' subcategory (P=0.008). The QOL score of the younger age group in the same subcategory was significantly improved by the treatment (P=0.013). The patients that had an increased overall QOL score 3 months after treatment initiation had a significant extension of progression-free survival (PFS) rate compared to the patients with decreased or no change in QOL (P=0.032). In conclusion, psychological stress was more prominent in younger patients with stage IV breast cancer treated with hormonal therapy compared with elderly patients. Importantly, improving QOL within the 3 months after treatment initiation could lead to longer PFS rate.