Relatives of men with fertility issues may be at higher risk of cancer

The relatives of men with fertility issues may be at an increased risk of cancer, with the odds varying considerably from one family to the next.

A study suggests that certain relatives who are within three generations of such men are more likely to develop a range of cancers, including those affecting the colon, testicles and uterus. But the risk varies between family lineages and also depends on whether the man is infertile or has low fertility.

Male infertility has been linked to multiple health issues, such as cardiovascular conditions. Previous research has also pointed towards links between male infertility and an increased cancer risk for such men’s relatives.

Joemy Ramsay at the University of Utah in Salt Lake City and her colleagues suspected this may vary among families. To find out, they analysed the sperm counts of 360 men who produced less than 1.5 million sperm per millilitre of semen, which is considered very low, and 426 who produced no sperm at all. These men were age-matched to more than 5600 others who had at least one biological child. The researchers do not know if any of the participants were transgender.

They then acquired information from Utah databases about any cancer diagnoses among the men’s first, second and third-degree relatives.

The team found that relatives within three generations of men with low sperm counts were more likely to have colon and testicular cancers, compared with the general population, while some of those who were related to men with no sperm were more likely to have sarcomas, Hodgkin lymphomas and cancers of the uterus and thyroid. For both these groups, bone and joint cancers occurred at a much higher rate than in the general population.

Next, the researchers used specially developed software to detect the tendencies within different families – in both the fertile and infertile groups – to have an increased risk of any combination of cancers in 34 parts of the body. This led to “clustering” that allowed them to detect trends within families.

Among the relatives of men with no sperm, two-thirds had no greater risk of cancer than the general population. The others, however, had significantly increased risks of various types of cancer, which varied among the families, with some showing higher risks for paediatric, adolescent and young-adult cancers.

For the relatives of the men with low sperm counts, all had an increased risk of at least one kind of cancer compared with the general population, but the extent of the risk and the type of the condition varied.

Why these increased risks occur is unclear, but it may be due to genetics or shared environmental exposures among the relatives. Further studies should look into this and hopefully lead to tests that identify families at greater risk, says Ramsay.