Clinical significance of colonoscopy follow-up for colorectal cancer in Chinese Lynch syndrome mismatch repair gene mutation carriers

Abstract

Objective To explore the clinical significance of colonoscopy follow-up in Chinese Lynch syndrome mismatch repair (MMR) gene mutation carriers. Methods The results of colonoscopy follow-up was analyzed in 194 MMR gene mutation carriers of 50 Lynch syndrome families. The follow-up period was from April 2001 to November 2016. The detection rates of advanced adenomas and colorectal cancers, five-year survival rate and ten-year survival rate were compared between 123 patients of regular follow-up group (colonoscopy interval less than two years) and 71 patients of irregular follow-up group (time colonoscopy interval more than two years). T test, chi-square test and Kaplan-Meier method were performed for statistically analysis. Results The incidence of colorectal cancer of irregular follow-up group was significantly higher than that of regular follow-up group (57.7%, 41/71 vs 22.8%, 28/123); and the difference was statistically significant (χ2=24.00, P<0.01). The average age at diagnosis for colorectal cancer in irregular follow-up group was younger than that of regular follow-up group ((45.3±1.9) years vs (48.7±1.8) years); and the difference was statistically significant (t=4.10, P<0.01). In regular follow-up group, 28.6% (8/28) advanced-stage colorectal cancer (TNM Ⅲ or Ⅳ) was found, while in irregular follow-up group, 73.2% (30/41) advanced-stage colorectal cancer was found, and there was statistically significant difference in pathological stage between two groups (χ2=4.90, P=0.032). The five-year and ten-year survival rates of regular follow-up group were 96.2% and 85.1%, respectively, which were both higher than those of irregular follow-up group (46.3% and 28.7%); and the differences were statistically significant (χ2=13.20 and 14.80, both P<0.05). The incidence of advanced adenomas of irregular follow-up group was significantly higher than that of regular follow-up group (49.3%, 35/71 vs 18.7%, 23/123); and the difference was statistically significant (χ2=20.10, P<0.05). The detection rate of advanced adenomas of MMR gene mutation carriers was higher than those without MMR mutation gene (85.4%, 35/41 vs 14.6%, 6/41); and the difference was statistically significant (χ2=5.20, P<0.05). Conclusion Regular colonoscopy surveillance may decrease the incidence and mortality of colorectal cancer in MMR mutation carriers of Lynch syndrome families, and increase five-year and ten-year survival rates. Key words: Colonoscopy; Survival rate; Lynch syndrome; Follow-up