Fertility after young-onset colorectal cancer: a study of subjects with Lynch syndrome

Infertility is a concern for young survivors of colorectal cancer (CRC), but this risk is not well quantified. Carriers of mismatch repair (MMR) mutations are a useful cohort for studying fertility after CRC as they commonly develop CRC when young, and unaffected family members provide demographically similar controls. The aim of this study was to determine the effect of CRC on fertility in a large cohort of MMR mutation carriers.

Mismatch repair mutation carriers identified from the Australasian Colorectal Cancer Family Registry were included. For each year of life within the fertile age range (15-49), the number of living individuals and the number of children born to them were determined. Individuals were grouped by whether or not they had had a diagnosis of CRC by that age. Age-specific and total fertility rates were calculated.

We identified 1068 subjects (611 women and 457 men), of whom 467 were diagnosed with CRC. There were 1192 births during 18 674 person-years of follow-up to the women and 814 births during 14 013 person-years of follow-up to the men. The total fertility rate was decreased in women after a diagnosis of CRC compared with those who did not have CRC (1.3 vs 2.2; P = 0.0011), but age-specific fertility was only reduced in the 20-24-year age group. In men the total fertility rate was similar for both groups (2.0 vs 1.8; P = 0.27).

Age-specific fertility was decreased in female CRC survivors with Lynch syndrome aged 20-24, but not in older women or in men.