Usefulness of pharmacy outpatient clinic follow‑up for maintaining relative dose intensity in patients on adjuvant CAPOX chemotherapy for gastric cancer

Capecitabine plus oxaliplatin (CAPOX) is a frequently used treatment regimen for colorectal and gastric cancer as postoperative adjuvant chemotherapy. Nausea, vomiting and diarrhea are reported to be the main causes of decreased adherence to CAPOX therapy. The Cancer Institute Hospital, Japanese Foundation for Cancer Research, provides a pharmaceutical outpatient clinic for patients undergoing outpatient chemotherapy. In the present study, dose intensity and severity of side effects of CAPOX therapy as adjuvant chemotherapy after surgery for gastric cancer were evaluated before and after outpatient pharmacy clinic follow‑up. This was a retrospective, observational study. Data from consecutive patients who received CAPOX therapy as adjuvant therapy after surgery for gastric cancer from November 2015 to April 2021 were obtained. Two patients were excluded, and 59 patients were included in the analysis. In total, there were 243 prescription recommendations at the pharmacy outpatient clinic. The most common prescription recommendation was prescription of supportive care medications (53.9%, 131 instances), followed by postponement of treatment (10.3%, 25 instances) and dose reduction of each drug (8.2%, 20 instances). The mean relative dose intensity (RDI) was 67.8±20.2% [95% confidence interval (CI), 62.5‑73.1%] for capecitabine and 62.2±20.7% (95% CI, 56.9‑67.6%) for oxaliplatin. The mean RDI was 72.5±18.8% (95% CI, 61.2‑83.7%) before capecitabine dose reduction and 90.4±14.8% (95% CI, 81.4‑99.3%) after dose reduction. The pharmacy outpatient clinic maintained RDI and contributed to the continuation of treatment by suggesting supportive care medications and recommending reduction of the dosage of anticancer drugs to the physicians.