Differences in cancer incidence among predominantly Muslim and Buddhist subpopulations in Songkhla.

BACKGROUND: The population of Songkhla, a province in Southern Thailand, can be divided into a predominantly Muslim subpopulation (PMSP, approximately 70% Muslim) and a predominantly Buddhist subpopulation (PBSP, around 14% Muslim).
OBJECTIVES: This study was conducted to 1) describe the incidence of various cancers in both PMSP and PBSP, and 2) compare the incidence of various cancers between the two subpopulations.
MATERIALS AND METHODS: Cancer cases diagnosed between 1990 and 2010 were drawn from the database of Songkhla Cancer Registry. Population denominators were estimated from the 3 population censuses surveyed by the National Statistical Office of Thailand in 1990, 2000, and 2010.
RESULTS: The age-standardized incidence rates (ASR) of the 5 commonest male cancers among both subpopulations were calculated. In females, a lower incidence of cancers of the cervix and breast in PMSP compared to PBSP, with odds ratios of 0.54 (95% CI: 0.45-0.64) and 0.51 (95% CI: 0.43-0.60) respectively, was observed. In males, the incidence of cancers of the lung, liver, colon-rectum, and some other cancers were significantly different between the two populations in the past, but only prostate cancer showed a lower incidence among males in PMSP in recent years. Independent of sex and year of diagnosis, the incidence of lung, liver, NHL, and colorectal cancers was lower in MPSP compared to BPSP, with odds ratios of 0.75 (95% CI: 0.65-0.85), 0.74 (95% CI: 0.62-0.88), 0.74 (95% CI: 0.60-0.91), and 0.67 (95% CI: 0.56-0.78) respectively.
CONCLUSIONS: The differences in incidence of some cancers and religion- related culture between the two subpopulations need 2 sets of cancer-control plans and goals to fit the unique population context in deep Southern Thailand. This plan can be used in the 3 southernmost provinces of Thailand where the percentage of Muslims is over 85%.