"Australians who ejaculated most frequently enjoyed a reduced risk of prostate cancer. The effect was strongest for the frequency of ejaculations in young adulthood, even though prostate cancer was not diagnosed until many decades later. Even so, the apparent protection extended to all age groups. In all, men who averaged 4.6–7 ejaculations a week were 36% less likely to be diagnosed with prostate cancer before the age of 70 than men who ejaculated less than 2.3 times a week on average."

Source: https://www.health.harvard.edu/mens-...rostate_cancer