# Adult brain cancer incidence patterns: A comparative study between Japan and Japanese Americans

## TL;DR

This study compares brain cancer rates in Japan and Japanese Americans to other U.S. populations, finding lower rates in both groups, suggesting a genetic influence.

## Contribution

The study provides new evidence supporting a genetic component in brain cancer risk by comparing incidence patterns across populations.

## Key findings

- Japanese and Japanese Americans had lower CNS tumor incidence rates than non-Hispanic whites in the U.S.
- Lower rates were consistent across age groups and tumor subtypes.
- Findings suggest genetic factors may outweigh environmental ones in CNS tumor etiology.

## Abstract

Adult primary brain and central nervous system (CNS) cancers, though comprising only about 4% of new cancer diagnoses, significantly impact morbidity and mortality due to their low survival rates. Globally, brain and CNS tumor incidence varies considerably, with the United States exhibiting one of the highest rates and Japan among the lowest worldwide. In the United States, incidence rates differ by race, with higher rates in non‐Hispanic whites (NHW) and lower rates in Asian Americans and Pacific Islanders (AAPI). This study examines the incidence of malignant CNS tumors in Japan and Japanese Americans, comparing these groups to NHW and AAPI populations in the United States. We estimated age‐standardized incidence rates (ASR) of brain and CNS tumors among adults using data from the Monitoring of Cancer Incidence in Japan (MCIJ) and the U.S. Surveillance, Epidemiology, and End Results (SEER)‐9 registries from 2007 to 2014. Incidence rates were stratified by age, sex, and specific CNS tumor subtypes. Incidence rates of CNS tumors among Japanese (ASR: 3.66, 95% CI: 3.56–3.76) and Japanese Americans (ASR: 2.5, 95% CI: 2.13–3.05) were lower than among NHW (9.43, 95% CI, 9.31–9.56) and AAPI populations (ASR: 4.13, 95% CI: 3.94–4.33) in the United States. The same pattern was observed for CNS tumor subtypes and across age groups and sex. This study supports a genetic component in the risk of brain and CNS tumors, a cancer type with largely unknown etiology. By comparing incidence rates across populations, it contributes to understanding the balance of genetic and environmental risk factors in the development of these cancers.

What's new?

The risk factors for brain tumors remain largely unknown. Building on the legacy of migration studies, this study compared the incidence of adult malignant brain and central nervous system tumors in Japan and among Japanese Americans and other ethnic populations in the United States. The results revealed lower incidence rates in both the Japanese and the Japanese American populations compared with the non‐Hispanic White population in the United States. This pattern remained consistent across sex and age groups. The findings suggest that genetic factors play a stronger role than environmental factors in the brain and central nervous system tumor etiology.