Background/Purpose: The relationship between gout and cancer remains unclear. Whereas some studies have reported possible anti-cancer benefits of uric acid and monosodium urate crystals, others have found an increased risk of cancer in gout patients. Our study aimed to clarify the relationship between gout and colon metaplasia, including cancer and polyps.

Methods: We conducted a retrospective study of patients in a VA hospital system using two distinct approaches. To obtain a historical, cross-sectional view of colon cancer prevalence, we assessed the presence of physician-coded diagnoses of colon cancer and/or polyps in gout patients, versus patients with osteoarthritis (OA) but no gout, with active records in our computerized patient record system (CPRS) between 2007 and 2008. Lung and prostate cancer prevalence were recorded for comparison. In the second approach, we included only patients with documented colonoscopy reports in CPRS, and performed a retrospective cohort study of colon cancer and polyp incidences in gout versus OA patients over a ten-year period (2001-2010).  In addition, colon cancer and polyp incidences were compared between patients who had undergone screening versus diagnostic colonoscopy, those who used aspirin or NSAIDs and those who did not, and between gout patients who used allopurinol and/or colchicine and those who did not.

Results: 1287 gout patients and 1287 OA patients were included. Gout and OA patients were similar in age, ethnicity, BMI and smoking history. Gout patients had a lower physician-coded prevalence of all colonic lesions (cancer or polyp: 1.8 versus 9.6%, p<0.001), and a lower prevalence of colon cancer (1.0 versus 1.9%, p<0.001), than OA patients (Figure A). Lung and prostate cancer were similar between the two groups. Among 581 gout patients and 598 OA subjects with documented colonoscopies, the ten-year incidence of colon cancer was lower in gout patients than in patients with OA (0.8 versus 3.7%, p=0.0008) (Figure B).  This difference in colon cancer incidence remained significant after accounting for NSAID and/or aspirin use. Among gout patients, the use of colchicine and/or allopurinol, as well as the presence or absence of concomitant of OA, did not appear to influence colon cancer prevalence.  Differences in colon cancer incidence were significant between gout and OA patients undergoing diagnostic colonoscopy (0.5% in gout patients versus 4.6% in OA patients, p<0.001) but not those undergoing screening colonoscopy (0.9% in gout patients versus 1% in OA patients, p=1.0). No protective effect of gout was observed for prostate or lung cancer.

Conclusion: Patients with gout had decreased physician-reported prevalence, and colonoscopy-documented incidence of colon cancer compared to patients with OA, suggesting a possible protective effect of gout or a gout-associated clinical, epidemiological or genetic factor.