Colorectal Cancer and Precancerous Lesions Associated with Ulcerative Colitis in Thailand.

Background: Ulcerative colitis(UC) is important risk factor of colorectal cancer. Many evidences from western countries confirmed this relationship but limited studies were reported in ASEAN. This study was aimed to investigate prevalence, clinical presentations, endoscopic findings, histopathology, disease progression and risk for colorectal cancer(CRC) of UC patients in Thailand. Methods: We conducted a retrospective cohort study using computer data base from Thammasat University Hospital, Pathumthani, Thailand between September 2011 and December 2015, follow-up through May 2016. Diagnosis of UC was confirmed by histopathology and whole clinical course. Results: We identified 6,082 patients who diagnosed with colitis during the study period. Of whom, only 22 patients(<1%) was confirmed of UC. Male to female ratio was 13:9 (mean age of 47.2 years). Clinical presentations were bloody diarrhea in 86.4%, watery diarrhea in 31.8% and abdominal pain in 59.1%. According to Montreal classification, disease extensions were ulcerative proctitis in 22.7%, distal UC in 50%, and pancolitis in 27.3%. Disease grading was mild in 31.8%, moderate in 9.1%, and severe in 59.1%. The prevalence of precancerous lesions were 2/22 patients(9.1%). There was no definite invasive colorectal cancer patient during study period. However, history of malnutrition was significantly higher in patients with dysplasia than those without dysplastic lesions(50%vs.0%, P-value=0.045). There was no difference in duration and disease extension between 2 groups. Interestingly, subgroup analysis demonstrated that pancolitis was significantly more common in female than male (55.6%vs.7.7%,P-value=0.02,OR=15.0, 95%CI=1.3- 169.9). Furthermore, patients’ age> 35 years had significantly more severe colitis than younger group (81.25%vs.0%, P-value=0.0006) Conclusions: Although UC is rare disease in ASEAN, precancerous lesions for CRC were not uncommon. UC with pancolitis was common in female whereas severe colitis was common in elderly patients. Proper screening program and careful surveillance for precancerous lesions in patients at risk might be appropriate approach for early detection and improvement the treatment outcome.