A new model can help identify the risk of colorectal cancer survivors developing a second primary tumour.

Writing in the Journal of the National Cancer Institute, the Australian and US researchers say the model provides individualised estimates of absolute risk for metachronous colorectal cancer (CRC) for up to 20 years after initial diagnosis.

Metachronous CRC is defined as a new primary tumour developing in a different part of the colon or rectum more than a year after the first diagnosis.

The model integrates 11 clinical, demographic and lifestyle factors to estimate the patient’s future risk, including age at first diagnosis; BMI (log transformed); smoking status; physical activity; family history of cancer; synchronous colorectal cancer; tumour stage, grade and histological type; and DNA mismatch repair status.