A real-world survey on expensive drugs used as first-line chemotherapy in patients with HER2-negative unresectable advanced/recurrent gastric cancer in the stomach cancer study group of the Japan clinical oncology group

Background Molecular-targeted drugs and immune checkpoint inhibitors have been developed for various malignant diseases, thereby improving clinical outcomes. However, these drugs are expensive, and few studies have assessed their actual use and costs in Japan. This study aimed to survey the use and costs of first-line chemotherapy for advanced/recurrent gastric cancer (AGC) in real-world settings. Methods The survey included patients with human epidermal growth factor receptor type2 (HER2)-negative AGC who initiated first-line chemotherapy from January 2022 to December 2022 at the participating 92 institutions in the Japan Clinical Oncology Group. Data on the regimens were collected using Google Forms. A regimen that costs >500 000 Japanese yen (JPY) per month was defined as expensive. Results Data on chemotherapy regimens were collected from 2173 patients at all 92 institutions between March 2023 and May 2023. We analyzed 2113 patients who underwent the chemotherapy with recommended regimens and conditionally recommended regimens according to the Japanese Gastric Cancer Treatment Guidelines sixth edition. The expensive regimens were triplet chemotherapy with fluoropyrimidine (S-1 or capecitabine or 5-fluorouracil/levofolinate), oxaliplatin, and nivolumab. Their monthly costs ranged from 767 648 to 771 046 JPY. Nivolumab-containing regimens cost more than 20 times the price of conventional chemotherapy with fluoropyrimidine and oxaliplatin. These regimens were used in 1416 (67%) of 2113 patients: in 71% of patients aged <= 74 years and in 59% of patients aged >= 75 years. Conclusion The regimens with >20-fold cost of conventional chemotherapy were used as first-line chemotherapy in two-thirds of patients and more than half even in the elderly population with HER2-negative AGC. This finding is important for future health economic studies on drug cost-efficacy.