20 June 2022.

New research based on data from the 45 and Up Study shows that having a vasectomy or being obese are both linked to an increased risk of advanced prostate cancer.

The study from The Daffodil Centre involved 107,000 men from the 45 and Up Study and looked at what behavioural and health-related factors were associated with the 4257 prostate cancer diagnoses (affecting 1 in 25 men) within the group between 2006 and 2013.

Researchers found that those who had a vasectomy were 1.3 times more likely to have advanced prostate cancer compared with those who hadn’t had the procedure. That same increase in relative risk was found in obese men compared with those with a normal BMI.

The link between BMI and prostate cancer has been shown in numerous studies, but a connection between vasectomies and prostate cancer has been strongly debated in recent years.

Australian men have a 1 in 8 chance of getting prostate cancer by the time they are 85, with an estimated 18,000 new prostate cancer cases diagnosed in Australia each year. Around 15% of those cases are advanced. Prostate cancer has one of the highest five-year survival rates of any cancer type, at 96%.

Around 30,000 Australian men get a vasectomy each year, with interest in the procedure reportedly surging during the pandemic

While vasectomies were linked to the risk of advanced cancer in the study, they had no link to increased risk of localised prostate cancer. The authors noted that this pattern was also found in the 24-year follow-up of the Health Professionals Follow-Up Study, which involved 49,000 men in the US.

“The biological mechanism underlying an association between vasectomy and prostate cancer risk is unclear,” the study authors say.

Family history was confirmed as one of the biggest risk factors of prostate cancer overall. Men whose fathers had prostate cancer were 1.4 times more likely to get the disease, and men with multiple first-degree family members affected were 2.2 times more likely to have prostate cancer, compared with men with no family history.

The study also found that certain medications were linked with a drop in overall prostate cancer risk. Men who took metformin, the diabetes medication, had a 43% lower risk than those who did not. Those who took prescriptions for benign prostatic hyperplasia (BPH) – an enlargement of the prostate gland that blocks the flow of urine – had a 24% lower chance of getting prostate cancer compared with those who did not.

“Metformin may have a role in prostate cancer prevention due to its glucose-lowering and anti-proliferative properties,” the study authors suggest, adding that further investigation into both metformin and BPH medication is needed.

The 45 and Up Study is the largest ongoing study of healthy ageing in the Southern Hemisphere. It’s made possible thanks to more than 250,000 dedicated participants across NSW, who are kindly sharing their health information with us to help create a healthier Australia.

If you’d like to stay up-to-date on the study, sign up for our newsletter or explore more of the research here.