Introduction Collagenous colitis (CC) is a syndrome of chronic, watery, non-bloody diarrhoea.1 Its worldwide incidence is increasing; emerging evidence suggests a possible association between CC and malignancy.2 However, studies thus far have been inconclusive and data on the incidence of metachronous extra-colonic malignancy (MEcM) in CC is scarce.3 This study aimed to determine the occurrence of MEcM in patients with CC.
Methods Retrospective study; data on MEcM in patients previously diagnosed with CC was collected within NHS Lothian (Scotland) over a 14 year period (Jan 2000 – Nov 2013). Person-years at risk were calculated according to age-specific categories. The standard error (Se) was calculated using the Poisson approximation. Relative risk (RR) and confidence interval (CI) of the age-standardised rate (ASR) were compared to publicly available population data for Lothian, Scotland.4 Results are reported as average ± standard deviation or RR with confidence interval (CI). P values <0.05 were considered statistically significant.
Results In the aforementioned period, 394 patients were diagnosed with CC and included for analysis. Thirty-three (21 F/12 M) developed MEcM, Table 1. The average age of the group with MEcM was 71.6 ±7.4 years compared to 65.9 ±13.6 years for the remainder of the patients (P < 0.05). The average duration of follow-up from CC diagnosis to MEcM was 2 ±2.23 years and for the group as a whole was 4 ±3.45 years. The RR for lung cancer (4.63, 1.30;16.49) and total cancers (2.34, 1.38;3.95) in patients with CC was higher compared to population data from Lothian (P < 0.05 for both).
Conclusion The RR of MEcM, including lung cancer, is higher in patients with CC.The increased RR for lung cancer may be explained by the association between CC and smoking.5
Further collective data will be useful to clarify other associations.
References 1 Münch A, et al. Microscopic colitis: current status, present and future challenges: statements of the European Microscopic Colitis Group. J Crohn’s Colitis 2012;6:932–945.
2 Freeman HJ. Complications of collagenous colitis. World J gastroenterol 2008;14:1643.
3 Chan JL, et al. Cancer risk in collagenous colitis. Inflamm Bowel Dis 1999;5:40–43.
5 Vigren L, et al. Is smoking a risk factor for collagenous colitis? Scand J Gastroenterol 2011;46:1334–1339.
Disclosure of Interest None Declared