Treatment patterns and clinical outcomes in patients with metastatic triple-negative breast cancer: a large-scale...

This study evaluated treatment patterns and clinical outcomes among patients with metastatic triple-negative breast cancer (mTNBC) in real-world clinical settings in Japan.

The treatment patterns, time to next treatment or death (TTNTD), time to treatment discontinuation, adverse events of interest, and medical costs of treating patients with mTNBC in first-, second-, and third-line settings were investigated using data of patients meeting the inclusion criteria between January 2017 and March 2022 in a Japanese medical claims database. The treatment regimens for mTNBC were defined according to the Japanese Breast Cancer Society Clinical Practice Guidelines.

In this study, 2236 patients with mTNBC (median age 66.0 years; 99.8% female) were included in the first-line cohort. Of these, 46.6% and 20.8% were included in the second- and third-line cohorts, respectively. The two most frequently used treatments were capecitabine (19.1%) and S-1 (tegafur-gimeracil-oteracil) (14.5%) in the first-line cohort, eribulin (18.3%) and bevacizumab/paclitaxel (14.4%) in the second-line cohort, and eribulin (19.4%) and bevacizumab/paclitaxel (17.5%) in the third-line cohort. The TTNTD shortened as the line of therapy progressed (median 8.0, 6.5, and 5.2 months for the first-, second-, and third-line treatments, respectively). Nausea/vomiting and neutropenia/leukopenia occurred in 62.8% and 18.3% of all patients, respectively. The medical total costs per day were 6.7, 10.2, and 12.9 thousand yen during the first-/second-/third-line treatments, respectively.

This study provides insight into current treatment patterns for mTNBC in Japan. The cost-benefit balance worsens with later-line treatment and a high unmet need for mTNBC drug treatment remains.