Introduction Olaparib is an oral poly (ADP-ribose) polymerase inhibitor that has shown antitumor activity in patients with advance or recurrent ovarian cancer. It is associated with adverse side effects, including fatigue, malaise, anorexia and anemia, which may force its discontinuation. Ninjin’yoeitou (NYT) is a herbal medicine that can effectively treat these adverse events. However, the efficacy of NYT in reducing these side effects with Olaparib is not clear.

Methods The present study included 45 patients who received Olaparib for newly diagnosed advanced or platinum sensitive recurrent ovarian cancer at eight Kansai Clinical Oncology Group (KCOG)-related institutions. Treatment-related adverse events were graded with use of the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0. Quality of life was assessed with the Functional Assessment of Cancer Therapy-Ovarian Cancer (FACT-O) questionnaire (completed at baseline and every month until 6 months had passed or disease progression), the FACT/NCCN Ovarian Symptom Index (FOSI), and the Trial Outcome Index (TOI).

Results Grade 3 or higher anemia occurred in 13 of 45 patients (29%), Grade 2 or higher fatigue in 6 (13%), and anorexia in 2 (4%). The incidence of discontinuation due to side effects was 15% (7/45). Moreover, NYT could maintain quality of life under all measures: FACT-O, TOI, and FOCI. NYT also significantly improved fatigue after the start of Olaparib administration (p=0.017).

Conclusion/Implications NYT could maintain quality of life by suppressing Olaparib-induced fatigue and help the long-term maintenance therapy of Olaparib in patients with ovarian cancer by reducing these adverse events.