Prevalence of Adenomas and Colon Cancer in People of Asian Origin in the United States Appears to Be at Least Similar to Those of Non Asians Undergoing Screening

Abstract

Introduction: Colorectal cancer is the second leading cause of cancer deaths in the United States. Cancer screening rates appear to vary based on race and ethnicity. Data on incidence of colorectal neoplasia in Asian Americans are not clear. AIM: To assess the prevalence of adenomas and colon cancer in Asian Americans undergoing screening at a large urban referral practice and compare them to non Asian Americans undergoing screening colonoscopy. Material and Methods: A retrospective analysis of Asian subjects undergoing a screening colonoscopy between January 2005 and June 2010 at a large urban referral practice was done. Ethnic origin was ascertained by use of NIH ethnicity codes. Data were abstracted using standardized abstraction sheets and included: age, reason for exam, location of the lesion, pathology of the lesion. The control group was comprised of 200 consecutive nonAsian subjects undergoing screening colonoscopy from January 2010. Those with prior history colon cancer or those undergoing colonoscopy for symptom evaluation were excluded. Results: A total of 144 subjects met the inclusion criteria in the Asian group. The frequency data were analyzed using Chi-square test while continuous data were analyzed by analysis of variance. The median age of the Asian group (63) at screening was higher than controls (53). The severity and grade of polypoid lesion was higher as the age increased in Asian subjects only. Further the incidence of all lesions was higher in the Asians as compared to the non-Asians (p=< 0.001). There was a trend for advanced adenoma to be more frequent in Asians (percent vs. percent), although the difference did not reach statistical significant (p=0.092) There was no significant difference in the location of lesions in the two groups (p= 0.732 in low-risk adenomas, p= 0.348 in advanced adenomas). We analyzed a subset of the population below 60 years of age (88 Asians; 200 non-Asians). The median age in the groups was the same (53 years). The incidence of all lesions was noted to be higher in the Asian group (p= 0.031), with subset analysis revealing higher incidence of low-risk lesions (p=0.025) but no statistical difference in advanced adenomas (p= 0.741). Conclusion: There are limited data about colon cancer screening in Asian-Americans. Our study highlights that Asian-Americans had screening done at a later age as compared to the general population. The incidence of low-risk lesions was higher in the study group even when the median age was same in both groups. The incidence of advanced lesions in the Asian population is at least similar to that in the non-Asian population. Asian Americans should adhere to the current guidelines and undergo screening at the age of 50. Limitations: Small sample size, lack of data on duration of residence, dietary habits.