Anatomical Distribution of Colorectal Carcinoma in Iran: A Retrospective 15-yr Study to Evaluate Rightward Shift

Background: Although more than two third of colorectal cancers are localized on the left side, recentstudies suggest a right ward shift in anatomical distribution with increase in proximal colon cancers. The aimof the present study was to determine the anatomical distribution of colorectal cancer in a referral center overa 15 year period.
Method: Records of patients who underwent colectomy in the Cancer Institute of Iran from1994 to 2009 were retrieved. Data including anatomical localization, year of diagnosis, patient age and gender,tumor histology and differentiation, and disease stage were extracted. Tumors located from the cecum to thedistal transverse colon were classified as right side and those occurring from the splenic flexure to the descendingcolon as left-sided. Cancer of rectum and recto-sigmoid junction were considered as rectal cancers.
Results: Atotal of 442 patients including 220 (49/8%) men and 222 (50/2%) women with mean age 53 were included. Mostpatients were in stage II &III (47.1% and 33% respectively). There were 157 (35.5 %) colon cancers and 285(64.5%) rectal cancers. 43.3% of the colon cancers were right sided and 56.7% were left sided. There was nostatistically significant increase in right sided cancer during the period of the study. There were no significantdifferences in age at diagnosis, gender, grade and stage of tumor between the right and the left sided cancers.
Conclusion: No proximal shift over time was identified in our study.