A study of almost 40 thousand Israeli men has found that men who have fathered sons are at lower risk for prostate cancer than men who have daughters but no sons. The researchers suggest that this shows the Y chromosome is involved in prostate cancer.

“We studied the relative risk (RR) of prostate cancer in relation to sex ratio of offspring in a cohort of 38 934 Israeli men who were followed from the birth of their offspring (in 1964 through 1976) until 2005,” researcher Susan Harlap writes in JNCI, the Journal of the National Cancer Insititute.

“A total of 712 men were diagnosed with prostate cancer. Compared with men who had at least one son, men with only daughters had an increased risk of prostate cancer.” This elevated risk averaged 1.40 times the rtisk iof men with sons (ranging from 1.20 to 1.64 times).

“In men with one, two, or three or more offspring, the relative risks associated with absence of sons were 1.25 . . . and 1.60 . . . respectively. Men with no daughters showed no statistically significantly altered risk, compared with men who had offspring of both sexes. The relative risk of prostate cancer decreased as the number of sons increased . . . but did not change with the number of daughters. These findings suggest that a Y chromosome locus may be involved in prostate cancer risk in this population.”