Abstract 4826: Cancer mortality attributable to area-level socioeconomic inequalities in Japan from 2015 to 2020

Abstract Background: In the 3rd Healthy Japan 21 and the 4th National Cancer Plan, the government focused on reducing health inequalities. However, current monitoring of socioeconomic inequalities in cancer is still insufficient to set the targets for the plan. To prioritize strategy aimed at reducing socioeconomic inequalities in cancer mortality, we estimated the population attributable risk fraction (PAF) and excess death due to socioeconomic inequalities, by sex, age group and cancer site. Method: We used the areal deprivation index (ADI) to establish area-based socioeconomic status. We categorized municipalities to ADI quintile weighted by the size of population, Q1 is the least deprived and Q5 the most deprived group. Excess death due to socioeconomic inequalities was calculated by the difference between observed number of deaths and expected death of Q2 to Q5 group with Q1 as standard population. We used cancer mortality data obtained from vital statistics in 2015-2020. Results: In total, about 12000 male and 2800 female excess deaths per year due to socioeconomic inequalities were estimated; that is 5. 5% and 1. 8% as PAF. PAF due to socioeconomic inequalities limited to premature death, less than 75 years old, was estimated as 7. 6% in men and 3. 3% in women. By age group, the 0-39 years group showed the largest PAF at 15. 7% in men and 16. 6% in women. In men of all age groups, except 0-39 years, lung cancer was the highest excess death due to socioeconomic inequalities. For women, some cancer sites (breast, ovary, esophagus) showed an opposite association, Q1 was the highest mortality group. Therefore, total excess death was lower than in men. In women of all ages, the highest rate of excess death due to socioeconomic inequalities was gallbladder cancer. For the 0-39 years group, a high rate of excess death in stomach, leukemia, and cervical cancer was observed. Discussion: Excess death and PAF due to socioeconomic inequalities differed by sex and age group. A greater impact of socioeconomic inequality on cancer mortality was observed in men than in women. Among women, further attention should be paid to areal variation of cancer death related to socioeconomic inequalities, based on the different area-based indices. Citation Format: Yuri Ito, Tomoki Nakaya, Manami Inoue, Tomotaka Sobue, Hitoshi Nakagama. Cancer mortality attributable to area-level socioeconomic inequalities in Japan from 2015 to 2020 abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 4826.