Some researchers say that testosterone therapy may increase your risk for prostate cancer, but more research is needed to understand the link.

Testosterone is a male sex hormone called an androgen. It’s produced in a man’s testes. Women’s bodies also produce testosterone, but in smaller amounts.

In men, testosterone helps maintain:

  • sperm production
  • muscle and bone mass
  • facial and body hair
  • sex drive
  • red blood cell production

In middle age, a man’s testosterone production starts to slow. Many men develop symptoms of low testosterone, or “low T,” which include:

When these symptoms are severe, they’re called hypogonadism.

Hypogonadism affects an estimated 2.4 million men over age 40 in the United States. By their 70s, one-quarter of men will have this condition.

Testosterone therapy can improve quality of life in men with low testosterone. However, it’s been a controversial practice since some research has suggested that testosterone fuels prostate cancer growth.

In the early 1940s, researchers Charles Brenton Huggins and Clarence Hodges discovered that when men’s testosterone production dropped, their prostate cancer stopped growing. The researchers also found that giving testosterone to men with prostate cancer made their cancer grow. They concluded that testosterone promotes prostate cancer growth.

As further evidence, one of the main treatments for prostate cancerhormone therapy — slows cancer growth by lowering testosterone levels in the body. The belief that testosterone fuels prostate cancer growth has led many doctors to avoid prescribing testosterone therapy for men who have a history of prostate cancer.

In recent years, research has challenged the link between testosterone and prostate cancer. Some studies have contradicted it, finding a higher risk of prostate cancer among men with low testosterone levels.

A 2016 meta-analysis of research found no relationship between a man’s testosterone level and his risk of developing prostate cancer. Another review of studies showed that testosterone therapy doesn’t increase the risk of prostate cancer or make it more severe in men who have already been diagnosed.

According to a 2015 review in the journal Medicine, testosterone replacement therapy also doesn’t increase prostate specific antigen (PSA) levels. PSA is a protein that’s elevated in the bloodstream of men with prostate cancer.

Whether testosterone therapy is safe for men with a history of prostate cancer is still an open question. More studies are needed to understand the connection. The existing evidence suggests that testosterone therapy may be safe for some men with low testosterone who have successfully completed prostate cancer treatment and are at low risk for a recurrence.

Although the role of testosterone in prostate cancer is still a matter of some debate, other risk factors are known to affect your odds of getting this disease. These include your:

  • Age. Your risk for prostate cancer rises the older you get. The median age of diagnosis is 66, with the majority of diagnoses occurring in men between the ages of 65 and 74.
  • Family history. Prostate cancer runs in families. If you have one relative with the disease, you’re twice as likely to develop it. Genes and lifestyle factors that families share both contribute to the risk. Some of the genes that have been linked to prostate cancer are BRCA1, BRCA2, HPC1, HPC2, HPCX, and CAPB.
  • Race. African-American men are more likely to get prostate cancer and to have more aggressive tumors than white or Hispanic men.
  • Diet. A high-fat, high-carbohydrate, and highly processed diet may increase your risk for prostate cancer.

While you can’t do anything about factors like your age or race, there are risks you can control.

Adjust your diet

Eat a mostly plant-based diet. Increase the amount of fruits and vegetables in your diet, especially cooked tomatoes and cruciferous vegetables like broccoli and cauliflower, which may be protective. Cut back on red meat and full-fat dairy products like cheese and whole milk.

Men who eat a lot of saturated fat have an increased risk of prostate cancer.

Eat more fish

Add fish to your weekly meals. The healthy omega-3 fatty acids found in fish like salmon and tuna have been linked to a reduced risk for prostate cancer.

Manage your weight

Control your weight. A body mass index (BMI) of 30 or higher might increase your risk for this cancer. You can shed extra weight by making adjustments to your diet and exercise routine.

Quit smoking

Don’t smoke. Tobacco smoke has been linked to many different types of cancer.

Prostate cancer often doesn’t cause any symptoms until it spreads. It’s important to know your risks and see your doctor for regular checkups to catch cancer early.

When symptoms do occur, they can include:

  • an urgent need to urinate
  • trouble starting or stopping the urine flow
  • a weak or dribbling urine flow
  • pain or burning when you urinate
  • trouble getting an erection
  • painful ejaculation
  • blood in your urine or semen
  • pressure or pain in your rectum
  • pain in your lower back, hips, pelvis, or thighs

These can also be symptoms of many other conditions — especially as you get older. If you have any of these symptoms, see a urologist or primary care doctor to get checked out.

Although doctors were once concerned that testosterone therapy might cause or accelerate prostate cancer growth, newer research challenges that notion. If you have low testosterone and it’s affecting your quality of life, talk to your doctor. Discuss the benefits and risks of hormone therapy, especially if you have a history of prostate cancer.