Real‐world emetic risk of chemotherapy and the corresponding antiemetic therapy in Japan: A study based on a nationwide database

BACKGROUND: Chemotherapy‐induced nausea and vomiting (CINV) is a major concern of patients with cancer, leading to suboptimal treatment. AIM: This study assessed the emetic risk associated with intravenous and oral chemotherapy and the prophylactic antiemetic drugs by cancer type in a real‐world setting. METHODS AND RESULTS: We used the health services utilisation data for patients with cancer diagnosed in 2016. Patients aged at least 20 years at the time of diagnosis and who started their first course of chemotherapy were included. The emetic risk of chemotherapy was determined according to the cancer type and was classified based on clinical practice guidelines. The prescription of antiemetic drugs was assessed. Overall, 172 133 patients were evaluated, of whom 121 103 (70.4%) received intravenous chemotherapy. High‐emetic‐risk chemotherapy (HEC) was prescribed in 46 458 (27.0%) patients. HEC was prescribed most for patients with oesophageal cancer (80.3%), followed by malignant lymphoma (60.2%) and breast cancer (53.8%). Moderate‐emetic‐risk chemotherapy (MEC) was prescribed in 60 528 (35.2%) patients and was mostly prescribed for small cell lung cancer (59.9%). Meanwhile, more than 50% of the chemotherapy prescribed for patients with gastric, colorectal, and pancreatic cancer was low‐emetic‐risk chemotherapy. HEC was accompanied by three‐drug antiemetic prophylaxis in more than 90% of patients with small cell lung, non‐small cell lung, breast, and oesophageal cancer, whereas only 13.5% of patients with malignant lymphoma were administered CHOP (cyclophosphamide, doxorubicin, vincristine sulphate, and prednisolone) with prophylaxis. CONCLUSION: The risk of CINV differs with cancer type. HEC was less prescribed compared with MEC. Most patients received the recommended anti‐emetic prophylaxis.