Increasing incidence and changing distribution of primary cancers in therapy‐related acute myeloid leukemia: A population‐based study in Osaka, Japan, 1990–2020

BACKGROUND: The clinical relevance of therapy-related acute myeloid leukemia (tAML) is increasing as the number of cancer survivors increases. The aim of this study was to determine the changes in the incidence and primary cancers of tAML over 30 years in a population-based setting in Japan. METHODS: Patients diagnosed with acute myeloid leukemia (AML) between 1990 and 2020 were identified using data from the Osaka Cancer Registry. Primary cancer was defined as the first preceding malignancy that was treated with chemotherapy and/or radiotherapy before the diagnosis of tAML. The impact of diagnosis period on tAML incidence was estimated using a negative binomial regression model. RESULTS: Of 9841 patients with AML, 636 (6.5%) had tAML. The annual tAML incidence increased during the study period, from 0.13 to 0.36 per 100,000 population. The proportion of tAML cases in overall AML cases almost doubled. A recent year was associated with increased annual tAML incidence (adjusted incidence rate ratio per 10 years, 1.28; 95% confidence interval, 1.05-1.55). The most common primary cancer was hematological malignancy (23.1%), followed by breast cancer (14.6%), colorectal cancer (11.5%), and gastric cancer (8.7%). The distribution of primary cancers changed between diagnosis periods, with a prominent increase of breast cancer and a decrease in gastric cancer. CONCLUSIONS: There was a gradual increase in the annual tAML incidence and a change in the distribution of primary cancers. These findings suggest an emerging concern regarding the burden of tAML as a post-cancer therapy complication.