The changing incidence and sites of colorectal cancer in the Israeli Arab population and their clinical implications.

Israeli Arabs have been at low risk for colorectal cancer (CRC) and had mainly proximal cancer, but increasing CRC is now noted. We examined this trend and CRC site and compared them to the total Jewish population and to the low-risk Jews of Asian-African origin. Israel Cancer Registry CRC data, 1982-2002, for Arabs and Jews was computed by gender, age and site: rectal cancer included recto-sigmoid junction; "right-sided" CRC included the proximal colon up to and also the splenic flexure. During 1982-2002, Arab CRC trends increased significantly in both sexes due to left-sided CRC (women, p = 0.01; men, p = 0.02) and rectal cancers (p = 0.05). Left-sided CRC increased significantly in both men and women aged > or = 65 years (p = 0.02). Comparing 1982-1984 to 2000-2002, the proportion of right-sided CRC decreased in both genders (p < 0.01) from 39.4 to 27.1% of male CRC, and from 44.8 to 31.3% in females. In general, this pattern of increasing rectal and left-sided CRC had been seen over a decade earlier in Jews of Asian-African origin and then their trend reversed during the last decade. In conclusion, there is a recent trend for left-sided CRC in Israeli Arabs, probably related to their changing life style. These results should influence their cancer preventive lifestyle recommendations, and CRC screening and diagnostic methodologies used.