Objectives: Migrant studies indicate that the differences in the incidence of colorectal cancer (CRC) are probably environmental and not genetic. There is epidemiological documentation that Israeli-born Arabs have much less CRC than Israeli-born Jews. We investigated these differences among Jews and Arabs living within the same central coastal region in Israel.
Methods: The files of pathology-diagnosed patients with CRC hospitalized from 1988 to 1996 were reviewed, and demographic data and incidence and location of malignancies were retrieved for this relative frequency study.
Results: Of the 527 patients (51.4% men) diagnosed as having CRC, 489 (92.8%) were Jews and 38 (7.2%) were Arabs (p < 0.001), representing 0.46% and 0.04% of the respective populations in the region. The average age at disease diagnosis of the Jews was 73.8 yr and that of the Arabs 61.4 yr (p < 0.001). Both groups shared identical health facilities and habits of attending them. The Arab patients were or had been employed in occupations that involved more physical activity. The site of lesion was on the right colon in 24.9% of all the cases-23.5% of the Jewish patients and 42.1% of the Arab patients (p < 0.001). Rectal cancer was found in 25.7% of the former and 15.8% of the latter (p < 0.001).
Conclusions: The lower incidence of CRC among the Arabs persisted over time, and that group had greater right side and lesser rectal involvement than their Jewish neighbors, possible indications of genicity. The incidence of CRC among the Jews rose concomitantly with "Westernization" of their lifestyle, supporting a role for environmental influences.