HOMOGENEITY OF THE SPATIAL-DISTRIBUTION O F CANCERS OF THE FEMALE REPRODUCTIVE-SYSTEM IN QUEBEC

Risk factors associated with women's reproductive life and sexual grow th do not adequately predict cancer incidence of the breast, uterus an d ovary. The heterogeneous worldwide distribution of. these cancers co uld imply that some environmental and cultural risk factors are involv ed in their cancerogenesis. The few attempts made so far to unravel th eir spatial structures at a geographic scale facilitating the search f or exogeneous risk factors have proved inconclusive. This study report s the results of a spatial analysis of the cancer incidence rates for breast, cervix, endometrium and ovary among Community Health Departmen ts (CHD) in Quebec using a spatial autocorrelation method. Correlogram s built according to four definitions of the inter-CHDs distance indic ate that breast and ovary incidence rates follow quite similar spatial gradients attesting to their etiologic affinity. They also suggest th at the spatial distribution of endometrial cancer follows a gradient d ivergent from that of breast and ovary cancers, and that the CHDs' spa tial scale does not suitably describe the distribution of cervical can cer. The demonstration of a structured spatial distribution for breast , endometrium and ovary cancers in Quebec strengthen the hypothesis th at cultural or environmental risk factors are involved in their etiolo gy. But, the observed disparities in the spatial structure of these ca ncers imply that their etiologic specificity may be greater than their biologic bond would suggest.