title: Evaluation of the left-to-right shift of colon tumors in Iran: Is the trend changing?
abstract: BACKGROUND
  Colorectal cancer (CRC) is the second cause of cancer-related deaths worldwide. There have been several studies reporting the proximal tumor shift, especially in Western countries. In the present study, we investigated the clinicopathologic and anatomical distributions of colorectal tumors in Iranian CRC patients.
  
  
  METHODS
  In this retrospective cohort study, 258 patients with CRC from 2008 to 2013 were evaluated. Comparison of variables was performed using Pearson's chi-square test and Fisher's exact test depending on the nature of the data.
  
  
  RESULTS
  A total of 258 patients including 124 (48.1%) females and 134 (51.9%) males enrolled in this study. The majority of cancers were detected in the rectosigmoid, i.e., 98 (38%) followed by the left colon, i.e., 84 (32.6%) and the right colon, i.e., 76 (29.5%). In the present study, we observed the significant association between metastases, adjuvant therapy, family history, and history of inflammatory bowel disease (IBD) with tumor, node, and metastasis (TNM) staging (P < 0.001). In univariate analysis, there was a strong association between overall survival (OS) and stage II CRC (P = 0.03). However, the predictive value was lost in multivariate analysis (P = 0.145).
  
  
  CONCLUSIONS
  Unlike the majority of previous studies on Iranian CRC patients, we observed a considerably higher occurrence of right-sided colon cancers (84 versus 76). Although this phenomenon did not reach the statistical significance rate, based on recent studies on Iranian population including the present one, the pattern of anatomical distribution of colorectal tumors has been changed toward the proximal colon. This requires an urgent need to provide other strategies and complementary detecting approaches in order to identify proximal tumors in Iranian CRC patients.
authors.affiliation: Gastroenterology and Liver Diseases Research center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Seyed Mohammad Hossein
authors.initials: SM
authors.lastname: Kashfi
authors.affiliation: Gastroenterology and Liver Diseases Research center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Nazemalhosseini Mojarad
authors.affiliation: Gastroenterology and Liver Diseases Research center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohamad Amin
authors.initials: MA
authors.lastname: Pourhoseingholi
authors.affiliation: Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Asadzadeh Aghdaei
authors.affiliation: Colorectal Division of General Surgery Department, Taleghani Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Fakhrialsadat
authors.initials: F
authors.lastname: Anaraki
authors.affiliation: Gastroenterology and Liver Diseases Research center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zali
keywords: Colorectal cancer (CRC); Iran; proximal shift; survival