This study examined the fertility rates of colorectal cancer patients who have lynch syndrome.

Colorectal cancer is a common cancer worldwide. In the United States 143,000 new cases are diagnosed every year. Roughly 4% of these new cases are patients under 45. For these young patients the impact of treatment on their chances of having children (fertility) can be a major worry.

Lynch syndrome is genetic mutation (abnormal genes) that makes people more susceptible to colorectal cancer. Having Lynch syndrome is also associated with having colorectal cancer earlier in life (average age at onset is 45 compared to 69 in patients without Lynch syndrome). Patients with Lynch syndrome may still want to have children at the time of colorectal cancer diagnosis. It is not clear whether treatment for colorectal cancer decreases patients’ chances of having children.

The authors analyzed fertility rates (number of children) in 1068 people (611 women and 457 men) with Lynch syndrome. 467 of these patients were diagnosed with colorectal cancer. 330 were under the age of 50 when they were diagnosed (285 colon cancer and 45 rectal cancer). Fertility rates were compared between patients with and without colorectal cancer. The fertility rates for patients at different age groups were also analyzed (age-specific fertility). Patients were followed-up for an average of 55 years.

Fertility rates for women decreased by approximately 40% after a diagnosis of colorectal cancer. Fertility rates were lower in women with colorectal cancer than those without (1.3 compared to 2.2 children). Both colon and rectal cancer were associated with decreased fertility compared to no colorectal cancer. The fertility rate in women with colon cancer decreased to 1.5 children compared to 2.2 children in women without colon cancer. The decrease was larger in women with rectal cancer (0.72 compared to 2.2 children). There was a significant decrease in fertility for women who were diagnosed between the ages of 20 and 24.

A colorectal cancer diagnosis did not affect age-specific fertility in men. Fertility rates were similar for men with colorectal cancer (1.8 children) compared to men without colorectal cancer (2.0 children). There was also no difference in fertility rates in men with colon or rectal cancer.

The authors concluded that women diagnosed with colorectal cancer between the ages of 20 to 24 had significantly decreased fertility. This decrease was not seen in men or older women.

Treatment for rectal cancer is thought to have a bigger impact on fertility than colon cancer treatment. As this study only included 45 rectal cancer patients younger than 50, the rates may not be an accurate representation of the risks for rectal cancer patients.

If you are scheduled to undergo treatment for colorectal cancer, discuss fertility risks and options with your doctor.