A new study but not a new association:

Dairy Foods, Calcium Intakes, And Risk Of Incident Prostate Cancer In Adventist Health Study–2, American Journal of Clinical Nutrition, 8 June 2022

Conclusions:
Men with higher intake of dairy foods, but not nondairy calcium, had a higher risk of prostate cancer compared with men having lower intakes. Associations were nonlinear, suggesting greatest increases in risk at relatively low doses.

Some perspective from Dr. Gary Fraser, study leader and an internal medicine and cardiovascular disease expert at Loma Linda University where the study was conducted:

Dr Fraser said the findings could suggest that dairy foods are ‘causally related to the risk of prostate cancer’.

He said this could be down to the sex hormone content of milk. Around three-quarters of milk comes from cows that are pregnant and prostate cancer is a ‘hormone-responsive cancer’.

Earlier studies found consuming dairy increases levels of a hormone in the blood called insulin-like growth factor-1, which is thought to increase the risk of developing some cancers.

Dr Fraser said he would encourage men with a family history of prostate cancer, or those with other risk factors, to ‘be cautious’ about drinking even ‘moderate levels’ of milk until the findings are clarified.

‘If you think you’re at higher-than-average risk, consider the alternatives of soy, oat, cashew, and other non-dairy milks,’ he said.