Hey doc, do us men need to masturbate in order to prevent prostate cancer or prostatitis? what happens if we choose not to masturbate at all? thanks

No harm either way: Masturbating or not masturbating will not have any measurable effect on your health. There is nothing wrong with masturbating and there will no harm if you do not. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, low fat milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex.

Your choice: Very few young men are able to go without having an ejaculation at least every few days, by whatever means. You need to be able to sit still, focus on work and learning, and get to sleep at night. There is no "controlled study", but there's some evidence that "heroic abstinence" puts you at greater risk for prostate hyperplasia ("hypertrophy") and prostatitis.