Prostate cancer develops when cells in the prostate gland begin dividing uncontrollably, but no single cause explains why this happens. Instead, a combination of hormonal signals, genetic inheritance, age, race, metabolic factors, and environmental exposures collectively raise or lower a man’s risk. About 13.2 percent of men will be diagnosed with prostate cancer during their lifetime, making it one of the most common cancers in men. Understanding what drives it can help you assess your own risk profile.
How Hormones Fuel Prostate Cell Growth
The prostate gland depends on male hormones, particularly testosterone and its more potent form, dihydrotestosterone (DHT). These hormones don’t just maintain normal prostate function. They also act as the primary fuel for most prostate cancers. When DHT binds to a receptor inside prostate cells, it triggers the receptor to move into the cell’s nucleus and switch on genes that promote cell growth and survival. This is the same signaling pathway that keeps healthy prostate tissue functioning, which is why the gland is uniquely vulnerable to cancerous overgrowth.
The length of a specific genetic repeat within the hormone receptor itself influences how strongly it responds to these signals. Men with shorter repeats have more active receptors, meaning their prostate cells respond more aggressively to normal hormone levels. This partly explains why two men with identical testosterone levels can have very different cancer risks.
What makes this pathway especially relevant is that prostate cancer cells can eventually learn to produce their own hormones. Even when treatments drastically lower testosterone throughout the body, cancer cells can convert precursor molecules from the adrenal glands into DHT locally, right inside the tumor. This ability to self-supply hormones is a key reason prostate cancer can persist and progress despite hormone-blocking therapies.
Age and Race
Age is the single strongest risk factor. Prostate cancer is rare before 40 and increases sharply after 50, with the majority of diagnoses occurring in men over 65. The accumulation of DNA damage over decades, combined with a lifetime of hormone-driven cell division, creates more opportunities for cancerous mutations to take hold.
Race plays a striking role. Black men in the United States develop prostate cancer at a rate roughly 60 percent higher than white men, and their mortality rate is more than double. The disparity goes beyond just getting diagnosed more often. Modeling studies estimate that by age 85, between 30 and 43 percent of Black men will have developed preclinical prostate cancer, a risk 28 to 56 percent higher than the general population. More concerning, Black men who do develop the disease face a 44 to 75 percent higher chance of having it progress to metastatic cancer by the time it’s found. This difference appears rooted in biology, including variations in hormone metabolism and tumor genetics, though disparities in healthcare access compound the problem.
Family History and Inherited Genes
Having a first-degree relative (father or brother) with prostate cancer roughly doubles your risk. Having multiple affected relatives pushes it higher still, and the disease tends to appear at younger ages in these families. Inherited mutations in the BRCA2 gene, better known for breast cancer risk, also significantly increase prostate cancer risk and are linked to more aggressive forms of the disease. Mutations in BRCA1 and a gene called HOXB13 carry elevated risk as well, though to a lesser degree than BRCA2.
Most prostate cancers, however, aren’t caused by a single inherited mutation. Instead, dozens of common genetic variants each contribute a small amount of additional risk. A man who carries many of these low-risk variants can end up with a cumulative risk similar to someone with a single high-impact mutation. This is why family history matters even when no specific gene mutation has been identified.
Chronic Inflammation
Long-term inflammation inside the prostate creates an environment where cancer is more likely to develop. A meta-analysis combining data from multiple studies found that men with a history of prostatitis (inflammation of the prostate) had roughly 50 to 64 percent higher odds of developing prostate cancer compared to men without that history. The link was strongest in studies based on self-reported prostatitis, with odds nearly 87 percent higher, while studies relying on clinical records showed a weaker association.
The biological explanation is straightforward. Chronic inflammation generates a steady stream of molecules called free radicals that damage DNA in nearby cells. It also promotes rapid cell turnover as the body tries to repair tissue, which increases the chances that a DNA copying error will go uncorrected. Over years or decades, this creates fertile ground for cancerous mutations. Sexually transmitted infections, urinary tract infections, and even dietary irritants that cause persistent low-grade prostate inflammation may all contribute to this process.
Insulin-Like Growth Factor (IGF-1)
A protein your body produces called insulin-like growth factor 1 plays a significant role in prostate cancer development. IGF-1 normally helps cells grow and repair, but elevated levels send a persistent “grow and survive” signal to prostate cells. Men with the highest circulating levels of IGF-1 have approximately 4.5 times greater risk of developing prostate cancer compared to men with the lowest levels. That’s a substantial increase, even among men whose PSA levels appear normal.
IGF-1 doesn’t just help tumors start. It promotes their ability to spread, resist radiation treatment, and survive hormone-blocking therapy. The tumor’s surrounding environment, including fat cells, immune cells, and connective tissue, communicates with cancer cells through growth factors like IGF-1, creating a supportive niche that helps the tumor grow and invade. This connection between metabolic health and cancer behavior is one reason obesity and insulin resistance are increasingly recognized as risk factors for aggressive prostate cancer, since both conditions tend to raise IGF-1 levels.
Diet and Supplements
The role of diet in prostate cancer risk is more nuanced than early research suggested. Diets high in red meat and dairy and low in fruits and vegetables have been associated with higher risk in population studies, though the effect sizes are modest. High-fat diets may contribute by raising hormone levels or promoting inflammation.
What the research makes clearer is that supplements don’t help and may actually cause harm. The SELECT trial, a large National Cancer Institute study, found that men who took vitamin E supplements had a 17 percent increase in prostate cancer diagnoses compared to men taking a placebo. That increase was statistically significant, not a fluke of chance. Men who took selenium supplements also saw higher rates, though those numbers were not statistically significant. Most notably, men who already had high selenium levels and then took additional selenium supplements had nearly double the risk of developing high-grade prostate cancer. And men who started with low selenium levels doubled their risk of high-grade cancer if they took vitamin E. The clear takeaway: there is no clinical evidence that any supplement reduces prostate cancer risk.
Environmental and Chemical Exposures
Certain occupational and environmental exposures are linked to higher prostate cancer rates. Agent Orange, the herbicide widely used during the Vietnam War, has received the most attention. The National Academy of Sciences concluded there is suggestive evidence of a positive association between herbicide exposure and prostate cancer. A 2013 study from the Portland VA Medical Center found that veterans exposed to Agent Orange were not only at higher risk for prostate cancer but more likely to develop aggressive forms of the disease.
Beyond Agent Orange, pesticide exposure in agricultural workers, cadmium exposure in welding and battery manufacturing, and firefighting chemicals have all been linked to elevated risk in occupational studies. The mechanisms likely involve direct DNA damage, hormone disruption, or both.
How These Factors Work Together
Prostate cancer rarely results from a single cause. A more realistic picture is one of layered risk: a man may inherit genetic variants that make his prostate cells slightly more responsive to hormones, live in an environment that exposes him to low-level carcinogens, carry extra weight that raises his IGF-1 levels, and experience chronic low-grade prostate inflammation as he ages. None of these factors alone would guarantee cancer, but together they create conditions where a cancerous mutation is more likely to occur and more likely to thrive once it does.
The factors you can’t change, like age, race, and inherited genetics, determine your baseline risk. The factors you can influence, like body weight, diet quality, and awareness of occupational exposures, modify that baseline. For men at higher risk due to family history or race, the U.S. Preventive Services Task Force recommends discussing PSA screening with a clinician starting before age 55, so that any cancer can be caught early when treatment options are broadest.