Prostate cancer: Increasing fitness level linked to lower risk

The study was an analysis of Swedish health records in which 57,652 men reported their physical activity levels, self-described health, lifestyle, and body mass and height measurements.

Each had also participated in at least two cardiorespiratory fitness tests on a stationary bicycle, with their cardiorespiratory fitness measure a V02 max test, which tracks oxygen inhaled and exhaled oxygen at maximum exercise levels.

During a mean followup time of 6.7 years, 46 men died of prostate cancer.

While Sweden’s health system provides excellent data for such studies, one concern is that the group of men studied is largely White Scandinavian men.

Black men — who are at the highest risk of prostate cancer — were not included.

Cardiologist Dr. Jayne Morgan, of GeoVax, who was not involved in this study, mentioned this as a key concern when speaking to Medical News Today. Yet this was not her only concern about the research.

Dr. Morgan noted a lack of information regarding “whether men with higher fitness levels or higher cardiorespiratory fitness also have different health habits with regard to types of food consumed, amounts of sleep obtained, hobbies, level of engagement with the medical establishment, obesity, employment — these men were all employed — and other lifestyle choices that can impact health and even cancer risk.”

Urologist and urologic oncologist Dr. Ramkishen Narayanan, from the Center for Urologic Health at the Disney Family Cancer Center in Burbank, CA, also not involved in the research, did, however, appreciate that the study focused on diagnosis of prostate cancer, and not mortality, since the number of men who die is so low that meaningful analysis is difficult.

“You’re talking about 1% at a mean followup of seven years. So that followup is not terribly long and the numbers are small,” he said.

Dr. Narayanan said he suspected a benefit from cardiorespiratory fitness would mostly be due to being healthier in general, mentioning its positive value for avoiding metabolic syndrome.

“Those are modifiable risk factors,” said Dr. Narayanan. “High blood pressure and obesity we know are risk factors that can contribute to different oncologic potential.”

Specifically, said Dr. Morgan, “[g]reater cardiac fitness is generally tied to greater overall fitness which is then tied to decreased abdominal fat, decreased weight, less insulin resistance, i.e. less type 2 diabetes [risk], and improved cholesterol profiles.”

Dr. Morgan explained that “[t]he common thread is chronic systemic inflammation, which is a risk factor for both cancer as well as heart disease.”

“Interestingly,” she noted, “cardiac disease is the leading cause of death in men with prostate cancer.”

Dr. Morgan also pointed out that for men being treated for prostate cancer with androgen deprivation therapy (ADT) there is an increase in cardiovascular risk.

Dr. Morgan listed the items she would like to see addressed in a subsequent, more robust study. These are:

1. utilize a VO2 max measurement that is validated.
2. control for co-morbidities and lifestyle factors.
3. perform randomized control trials.
4. include other populations, especially Black men
5. increase the number of timepoints
6. adjust and randomize for age.

Dr. Narayanan suggested essentially turning the study around, an idea also suggested by its authors: “I would look at a population with prostate cancer, and look at biochemical recurrence to observe whether strong [cardiorespiratory fitness] would align with a reduction in biochemical recurrence of the disease.”

After anybody gets treated for prostate cancer, their PSA levels are regularly monitored indefinitely.

“The biggest takeaway that I would have from this is that [promoting] cardiovascular fitness is something actionable and empowering that men can do as opposed to saying, well, it’s family history, it’s your genetic predisposition, and then feeling like they’re not able to take some preventable action.”

– Dr. Ramkishen Narayanan

He also mentioned that some men are fearful of working on cardiorespiratory fitness for fear of raising testosterone levels that they worry may increase their risk of prostate cancer.

“There’s a misconception,” explained Dr. Narayanan, “that increasing testosterone will increase your prostate cancer incidence. That’s really been disproven as a misconception. So that’s something that’s important to know.”