Risk factors for metachronous colorectal cancer following a primary colorectal cancer: A prospective cohort study.

Publication Type:

Journal Article

Source:

International journal of cancer (2016)

Abstract:

Individuals diagnosed with colorectal cancer (CRC) are at risk of developing a metachronous colorectal cancer. We examined the associations between personal, tumour-related and lifestyle risk factors, and risk of metachronous CRC. A total of 7,863 participants with incident colon or rectal cancer who were recruited in the USA, Canada and Australia to the Colon Cancer Family Registry during 1997-2012, except those identified as high-risk e.g. Lynch syndrome, were followed up approximately every 5 years. We estimated the risk of metachronous CRC, defined as the first new primary CRC following an interval of at least one year after the initial colorectal cancer diagnosis. Observation time started at the age at diagnosis of the initial CRC and ended at the age at diagnosis of the metachronous CRC, last contact or death whichever occurred earliest, or were censored at the age at diagnosis of any metachronous colorectal adenoma. Cox regression was used to derive hazard ratios (HRs) and 95% confidence intervals (CIs). During a mean follow-up of 6.6 years, 142 (1.81%) metachronous colorectal cancers were diagnosed (mean age at diagnosis 59.8; incidence 2.7/1000 person-years). An increased risk of metachronous CRC was associated with the presence of a synchronous CRC (HR=2.73; 95% CI: 1.30-5.72) and the location of cancer in the proximal colon at initial diagnosis (compared with distal colon or rectum, HR=4.16; 95% CI: 2.80-6.18). The presence of a synchronous CRC and the location of the initial CRC might be useful for deciding the intensity of surveillance colonoscopy for individuals diagnosed with CRC. This article is protected by copyright. All rights reserved.