Prostate Cancer: Study Finds Better Way to Predict Mortality Risk

Prostate cancer causes almost 400,000 deaths each year, globally. Although it mostly affects older adults, according to the authors of the new study, around one-third of men who die from prostate cancer die before 75.

One way to identify men at risk of prostate cancer is by calculating their polygenic risk score (PRS). In short, this method helps scientists spot gene variants that increase an individual’s risk of developing prostate cancer or dying from it.

According to the new study, men whose PRS is in the top 10% have a 40–50% chance of developing prostate cancer in their lifetime. The study researchers say this would be a good population to target with lifestyle advice that may reduce the severity of the disease.

Risk factors for prostate cancer can be nonmodifiable, in other words, individuals have no control over them. Or risk factors can be modifiable, meaning changes in lifestyle can decrease the risk of developing cancer.

Healthline spoke with Trevor Royce, MD, a radiation oncologist, adjunct faculty with the Department of Radiation Oncology at Wake Forest School of Medicine, and senior medical director at the precision medicine company Artera.

Royce pointed out that non-modifiable risk factors include:

• Age: The older a man is, the greater the chance of getting prostate cancer.
• Race and ethnicity: African American men are more likely to be diagnosed with prostate cancer.
• Genetic factors: Genetic risk factors may put some men at higher risk of prostate cancer.

However, some risk factors are modifiable. These include:

There is some evidence that men with a higher risk of developing prostate cancer — for instance, those with a higher PRS — may benefit most from lifestyle interventions.

To investigate whether prevention can help reduce the mortality risk for people with genetic risk, the scientists accessed information from almost 20,000 people in the U.S. and Sweden and followed them for around 20 years. All subjects were prostate cancer-free at the start of the study.

The researchers also accessed their genetic data and information about their lifestyle and diet. By combining smoking status, exercise levels, body weight, and dietary factors, the researchers gave each individual a healthy lifestyle score. They also calculated their polygenic risk score (PRS) which factors in genetic markers for prostate cancer.

During the study’s follow-up, there were 444 deaths from prostate cancer. The analysis showed that both genetic and lifestyle factors increased the risk of death from prostate cancer.

Death before 75 was considered an early death, and deaths after 75 were deemed late.

Compared with individuals with a low PRS, those with a high score had a 3-fold increased risk of early death from prostate cancer and a 2-fold increased risk of late death from prostate cancer.

In further analyses, the authors showed that an unhealthy lifestyle only appeared to increase the rate of prostate cancer death among men with a higher PRS. In other words, lifestyle factors seemed less important for people with a lower genetic risk.

The lifetime risk of prostate cancer death was lowest for men with a lower genetic risk: 0.6%–1.3%. Men in the top 25% of PRS scores had a risk of 3.1%–4.9%. Overall, the highest risk was in participants with both a high PRS and an unhealthy lifestyle.

When the researchers analyzed early cancer deaths — before the age of 75 — they found that most of these deaths (88%) were individuals with a high genetic risk score.

They also estimate that lifestyle modifications could prevent many of these deaths:

“Importantly, we estimated that approximately one-third of early prostate cancer deaths among men in this group may be preventable through behaviors associated with a healthy lifestyle.”

Healthline spoke with Jeffrey S. Yoshida, MD, the medical director of urologic surgery at City of Hope Orange County in Irvine, CA.

“We know that the best way to stop cancer is to prevent it in the first place. Certain lifestyle factors can impact your risk of developing cancer and adopting healthy habits has been shown to reduce the risk of prostate cancer,” Yoshida said.

“I can’t emphasize enough how essential a healthy lifestyle is for good prostate health,” he continued. “Research has shown that nutrition plays a key role in reducing prostate cancer risk.”

He suggests reducing intake of processed meat and saturated fat, while upping fruit and vegetable intake.

The current study does have certain limitations. For instance, they only had information about participants’ lifestyles at the time they joined the study — people’s habits and diets can change significantly over the years.

Speaking with Healthline, S. Adam Ramin, MD, board-certified urologist, urologic oncologist, and medical director of Urology Cancer Specialists in Los Angeles, CA, said, “this study does not address how lifestyle changes can reduce the chances of developing prostate cancer.” Rather, it focuses on reducing the chance of dying from prostate cancer.

Ramin said he is positive about the findings:

“Studies like the above help screen for those men with higher risk prostate cancer and help lower the risk of death from these cancers. They also support our efforts in promoting healthy eating, exercising, and lifestyle changes for our patients.”

We also spoke with Przemyslaw Twardowski, MD, who was not involved in the study.

Twardowski is a board-certified medical oncologist, a professor of medical oncology, and director of clinical research in the Department of Urology and Urologic Oncology at Providence Saint John’s Cancer Institute in Santa Monica, CA.

“It is assumed that addressing these modifiable lifestyle factors would reduce the risk of developing potentially fatal prostate cancer,” he told us, “although at this point, this has to be treated as a viable hypothesis and not a conclusive proof,” Twardowski said.

However, he believes these results will “be helpful in earlier detection of cancer by more aggressive screening of high-risk individuals but also lifestyle intervention.” As important as genetics are,” he continued, “modifiable factors also play a role, and addressing them can be emphasized in our patient counseling.”

The cost of genetic tests may also be an issue if oncologists decide that this testing should be rolled out more broadly. “In general, though, genetic testing is becoming widely accessible and affordable as prices of these tests have come down dramatically in recent years,” Twardowski told Healthline.

However, according to Ramin, currently “there is no known standardized test that specifically tests for the 400 genes that are examined in the PRS. At this point, PRS is more of a research tool than a validated laboratory test.”

Overall, the authors conclude that “Implementing interventions among men at increased genetic risk may substantially reduce the number of early deaths due to prostate cancer.”

In the meantime, Royce provided this advice: “One of the most important things men can do is talk to their doctors about their prostate cancer risk and go for their recommended screenings.”

“Early detection can impact cancer survival,” he said.

A recent study finds that the vast majority of early prostate cancer deaths are in people with a high genetic risk. They also conclude that around one-third of these deaths could be avoided with lifestyle changes, including a healthy diet, exercise, and avoiding tobacco.