Abstract Background In the French West Indies, previous studies have reported findings on pesticide exposure and cancer incidence. A new exploratory geographical study, including a more sensitive soil contamination indicator, will provide more detailed information on the link between cancer incidence and organochlorine pesticide exposure. This study aims to investigate the association between incident cases of cancer and chlordecone soil contamination at an IRIS scale over the period 2006–2019 in Martinique. Methods Data on the 18 most frequent cancer sites were collected from the Martinique Population Based Cancer Registry. First, smoothed standardized incidence ratios at the level of the 141 IRIS were estimated, and then regression models including the smoothed standardized ratios were performed between cancer incidence and soil contamination index by sex and cancer site, using the Besag, York and Mollié models. Models were adjusted using an index of social deprivation. Results 23,218 cancer cases were eligible for this study, with 21,920 cases included in the final analysis. Soil contamination was associated with a higher relative risk of cancer in women than in men, but no significant correlation was found for breast cancer in women or for prostate cancer. Lung, thyroid, stomach and rectal cancers in women, and melanoma in men, all increase significantly with the level of contamination. There was a significant increasing gradient in the incidence of multiple myeloma in men, from reference to highly contaminated areas. Conclusion Integrating the latest available data on soil contamination and cancer incidence will extend on-going knowledge of chlordecone exposure and cancer incidence, which remains a major environmental concern in Martinique. Unexpectedly, our results show that the female population of Martinique is the most affected by chlordecone soil contamination.
