Prostate cancer is the second most common cancer in men. It usually grows very slowly and is unlikely to cause serious problems unless it spreads to other parts of the body. Western dietary patterns rich in dairy products seem to increase the risk of prostate cancer.
Prostate cancer is a disease in which cells in the prostate gland — a walnut-sized gland in the male reproductive system that resides below the bladder and surrounds the upper part of the urethra (i.e., the tube that carries urine from the bladder) and makes seminal fluid — start to grow out of control. It is the second most common cancer in men worldwide and is most prevalent in men over the age of 65; The majority of prostate cancers grow very slowly and are unlikely to cause serious problems. When the cancer is confined to the prostate, long-term prognosis is excellent, but if the cancer begins to grow quickly and spreads to distant organs, it becomes dangerous, and current therapies cannot cure it.
The signs and symptoms of prostate cancer are nonspecific and tend to be more indicative of benign prostatic hyperplasia (i.e., noncancerous enlargement of the prostate) than cancer. They’re mainly related to problems with urinating and include:
- Decreased urinary stream that’s hard to start, or starts and stops
- Frequent urination, especially at night
- Suddenly needing to urinate right away
- Incomplete bladder emptying
- Pain or burning while urinating
- Blood in the urine or semen Although rare in the current era of widespread screening, people with prostate cancer may also present with symptoms of metastatic disease (i.e., the spread of cancer cells to other parts of the body), such as bone pain or fractures.
A doctor can use different tests to screen for prostate cancer, such as a digital (finger) rectal exam, a prostate-specific antigen (PSA, a protein secreted by prostate cells) blood test, and imaging tests (e.g., ultrasound, magnetic resonance imaging). A prostate biopsy is then used to confirm the presence of prostate cancer and determine the severity of the disease.
The treatment selected depends on a variety of factors, including age, comorbidities, expected lifespan, the stage (i.e., the size of the tumor and whether the cancer has spread to other parts of the body) and grade (i.e., how abnormal the cancer cells and tissue look under a microscope and how quickly the cancer cells are likely to grow and spread) of the cancer, and patient preferences. Common treatment options include watchful waiting or active surveillance, surgery, radiation therapy, hormone therapy, chemotherapy, targeted therapy, and immunotherapy.
Watchful waiting or active surveillance is typically reserved for older men without symptoms and prostate cancer that isn’t likely to grow or with comorbidities that would affect their immediate lifespan. Surgery or radiation therapy are used in the early stages of prostate cancer to try and cure the disease.
Because oxidative stress is implicated in the development of prostate cancer, phenolic compounds and micronutrients with antioxidant effects have mainly been studied for reducing the risk of or treating the disease:
A Western dietary pattern rich in animal-based protein, dairy products, and refined carbohydrates tends to be associated with an increased risk of prostate cancer, whereas a healthy plant-based dietary pattern (e.g., the Mediterranean diet) tends to be associated with a decreased risk of prostate cancer. Concerning specific dietary factors, a notable body of evidence indicates that a high intake of dairy products is associated with an increased risk of prostate cancer, while fairly consistent evidence indicates a high intake of lycopene from tomato products is associated with a decreased risk of prostate cancer. Also, obesity increases the risk of advanced prostate cancer, so a hypocaloric diet that facilitates weight loss is often beneficial in this population.
The precise causes of prostate cancer are unclear, but they involve changes in the DNA of a normal prostate cell, which are either inherited or acquired throughout life. Several genes have been linked to prostate cancer (e.g., TMPRSS2-ERG, SPOP, FOXA1, BRCA1, BRCA2). Additionally, the risk of prostate cancer is approximately doubled in men who are Black or have a first-degree relative with prostate cancer compared to the general population. Acquired gene mutations are the result of errors in the DNA replication process, which occur at random or via the influence of other factors (e.g., diet, hormone levels, exposure to cancer-causing chemicals).