Clolrectal cancer (CRC) and cancer precursor lesions (adenomas) in the young average risk population of Qatar

Abstract

Background: The incidence of Colorectal Cancer (CRC) peaks in the sixth and seventh decade of life and its precursor lesions a decade earlier in average risk population. American College of physicians (ACP) recent guidelines suggests CRC screening at 50 years of age and older in average risk persons to detect and treat colorectal cancer precursor lesions and early cancers. Objective: To delineate the incidence of Colorectal Cancer (CRC) and Cancer Precursor Lesions (CPL) in the 30 - 49 years age group in symptomatic and asymptomatic average risk population of Doha, Qatar. Method: Lower gastrointestinal endoscopies are routinely done in Qatar for diagnosis and treatment for patients presenting with lower abdominal pain, bleeding or worsening constipation. A retrospective collection of data was done to know the incidence of CRC and CPL among all the patients reporting to our hospital with above mentioned symptoms. Based on the results of this data, a cut off age was calculated with highest sensitivity and specificity for detection of CPL. A CRC screening program was then initiated among asymptomatic subjects with positive immunological fecal occult blood (iFOBT) and age > 40 years were invited for screening colonoscopy. Incidence of CPL (colorectal adenomas) and CRC was calculated prospectively in the average risk asymptomatic population among various age groups. Data regarding the incidence of CRC and CPL among symptomatic and asymptomatic (screened) population was compared. Results: A total of 1489 lower gastrointestinal endoscopies were done in symptomatic patients over a one year period. The mean age was 47.5 years, 935 were males with 71.3 % being expatriates. Overall, among the symptomatic people, CPL were detected in 14.5 % (n= 216) and CRC in 5.6 % (n= 84).Of these, CPL and CRC was detected in 22.6 % (n= 49) and 34 % (n=29) respectively in the age group of 30-49 years. Among the asymptomatic 1242 people who participated in the CRC screening keeping a cut-off age of > 40 years, 57 people (4.6%) were found to be positive for occult blood in stool. Of them, seven and five patients were detected to have CPL and CRC respectively between the age group of 40-74 years. In the 30-49 years age group, CPL was detected in 14.3 % (n=1) but without any CRC. Table 1. Conclusion: One-third of cancers (34%) and one-fifth of cancer precursor lesions (22 %) are detected in the 30-49 years age group in symptomatic patients in Qatar. Among the young (fourth decade of life) asymptomatic subjects, the incidence of cancer precursor lesion remains similar to symptomatic patients but without any obvious cancer. Hence, it is recommended that young symptomatic patients should undergo lower endoscopy early to detect cancer and cancer precursors. Larger studies are required in the asymptomatic subjects of 40-49 years age group to estimate the incidence of pre-cancerous lesions that might benefit from CRC screening.