Supplementary Material for: A comprehensive literature-based analysis of prognosis in patients with Cronkhite-Canada syndrome.

Background: Cronkhite-Canada syndrome (CCS) is a rare, nonhereditary gastrointestinal disorder with unclear etiology and limited treatment consensus. Given the scarcity of data, we aimed to construct a pooled literature-based cohort to analyze survival outcomes and identify prognostic factors to inform future therapeutic strategies.
Methods: We developed a literature-based cohort of Cronkhite-Canada syndrome by extracting individual patient data from published case reports and two in-house cases. Articles were selected through a systematic screening process based on relevance and data availability. Information collected included age, sex, clinical symptoms, laboratory findings, endoscopic and histological features, treatment approaches, and outcomes. The compiled dataset was used to explore clinical characteristics, treatment patterns, and survival trends across reported cases.
Results: A total of 200 CCS patients were analyzed, including 198 from literature and 2 in-house cases. Most patients presented with diarrhea, weight loss, skin pigmentation, and alopecia. Polyps were commonly found in the stomach and colon. Survival analysis showed a 1-year survival rate of 92.3% and a 3-year survival rate of 79.9%. Male sex was associated with poor prognosis. However, multivariate analysis showed no significant predictors. Treatment with corticosteroids significantly improved survival, especially with high doses (≥ 40 mg/day). Surgical intervention tended to correlate with poorer outcomes. These findings suggest that appropriately dosed corticosteroid therapy may enhance long-term prognosis in CCS.
Conclusions: Using a comprehensive analysis of literature-based Cronkhite-Canada syndrome cases and our in-house cases, this study demonstrated the clinical characteristics of CCS. Our data showed the prognostic value of sex and surgical intervention, and the significance of high dose corticosteroid therapy on the treatment of CCS.