Hereditary nonpolyposis colorectal cancer in Pakistan: Results of a pilot study

Objective: Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditary bowel cancer. Multiple generations are affected with colorectal cancer at relatively young age, between 25 and 45 years. We conducted this study to investigate the frequency of HNPCC in Pakistani population, due to the high incidence of colorectal cancer in younger Pakistani adults and prevalence of consanguinity in this region.
Methodology: Ninety histopathologically confirmed colorectal cancer patients between 12-50 years and their families were interviewed using a detailed questionnaire. The questions about family history of colorectal cancer, history of other cancers, age at diagnosis and consanguinity were asked. The pedigrees were drawn for all families based on given information. To confirm cancers reported in relatives, hospital records were also reviewed. Amsterdam criteria were used to label a family as HNPCC.
Results: Seventeen patients (18.9%) had one or more first or second degree relatives under age 50 years with colorectal cancers suggestive of HNPCC. Another 15 patients (16.7%) had first or second degree relatives with a family history of other extra-colonic cancers including ovarian, breast, endometrium, lung, parotid, brain and bladder cancer. Of these 30 patients (33.3%) reported that their parents were first degree cousins.
Conclusion: High frequency of HNPCC was seen in Pakistani population; higher proportion of colorectal cancer in young Pakistanis, strong prevalence of consanguineous marriages could be important factors for HNPCC occurrence in Pakistan. However future studies with large sample size along with genetic testing and screening programmes are warranted.