潰瘍性大腸炎患者におけるdysplasiaの経過と発癌に関する検討―厚生労働省研究班分類に基づく検討―

抄録

Purpose: This study was undertaken to clarify the clinical significance of dysplasia graded according to the Ministry of Health, Labour and Welfare study group classification (none, UC-I, IIa, IIb, or III) in patients with ulcerative colitis (UC).

Subjects and Methods: We analyzed the clinical features, colonoscopy findings, incidence of malignancy, and risk factors for malignancy in 420 UC patients who underwent colonoscopy at our hospital. These patients were stratified by the histopathological grade of dysplasia at initial biopsy. We focused on the clinical course and the factors associated with malignancy in patients with UC-III dysplasia (severe dysplasia) during the observation period.

Results: The median observation period of the 420 patients was 7 years. Endoscopy generally showed a significant increase of elevated lesions as the grade of dysplasia increased. The incidence of malignancy increased along with the grade of dysplasia. Patients with UC-IIa or higher dysplasia had a significantly higher incidence of malignancy compared to those with UC-I or no dysplasia (p<0.05). Juvenile onset of UC and inflammatory polyps were significantly associated with malignancy. During the observation period, UC-III dysplasia was detected in 29 patients. Among them, 8 patients (27.6 %) developed cancer, with the median period until detection of UC-IV being 2.5 months.

Conclusion: Careful follow-up by surveillance colonoscopy is required for patients with UC-IIa or higher dysplasia. Early detection of dysplasia (suggesting the presence of precancerous lesions), inflammatory polyps, and juvenile onset are useful for predicting a higher risk of colitis cancer.