PROSTATE CANCER OVERVIEW
Prostate cancer is usually slow growing and seldom causes symptoms until it enters an advanced stage. Most men who develop prostate cancer die from other causes, and they may even be unaware they have it. However, once the cancer begins to grow quickly or when it spreads beyond the prostate gland, it becomes threatening. Whether and how prostate cancer grows is different from one individual to another, and it is difficult to predict accurately how it will continue to develop in a specific person.
Types of Prostate Cancer
Localized prostate cancer refers to cancer that affects the prostate gland, has not spread to lymph nodes, and has not formed tumors in other areas of the body (metastasis) (IQWiG, 2020).
There are many types of prostate cancer; adenocarcinoma, diagnosed in 99% of prostate cancer cases, is the most common type (CTCA, 2021a). This type of cancer may occur anywhere in the body and forms in the glandular epithelial cells lining organs that secrete mucus or other fluids. Adenocarcinoma in the prostate is also referred to as glandular prostate cancer. There are two main subtypes of adenocarcinoma:
- Acinar, a cancer that accounts for practically all prostate adenomas
- Prostate ductal adenocarcinoma (PDA), a rarer and more aggressive type of adenocarcinoma, which is hard to detect, as it does not always increase PSA (prostate specific antigen) levels
(CTCA, 2021a)
Other prostate cancers are very rare and include:
- Transitional cell carcinoma (or urothelial cancer), which spreads to the prostate from the urethra or bladder
- Neuroendocrine tumors (carcinoids), which appear in nerve and gland cells that make and release hormones into the bloodstream
- Small-cell carcinoma, the most aggressive type of neuroendocrine cancer
- Squamous cell carcinoma, a very rare but fast-growing form that starts in fat cells covering the prostate gland
- Prostate sarcoma, which develops outside the prostate gland in the soft tissue of the prostate (muscles and nerves)
(CTCA, 2021a)
Risk Factors for Prostate Cancer
The exact cause of prostate cancer is not known, but certain factors are known to increase the risk. These include:
- Age: Age is the greatest risk factor, and prostate cancer risk increases with age.
- Close relatives with prostate cancer: Having a blood-relative father or brother increases risk, and having several other close relatives with prostate cancer increases risk even higher.
- Family history of breast cancer: Having a family history of genes that increase the risk of breast cancer or family history of breast cancer raises the risk for prostate cancer.
- Ethnicity: Black men have a somewhat higher risk.
- Obesity: Obesity raises the risk of prostate cancer, although studies have shown mixed results. In obese patients, the cancer is more likely to be more aggressive and more likely to return after initial treatment.
- Vitamin E: Dietary supplements with a high level of vitamin E have been shown to increase risk 17% if taken over many years. No biological mechanism has been proposed to explain the increase.
(OSU, 2021)
No high-quality studies have been done that show that diet influences risk (IQWiG, 2020; Mayo Clinic, 2021a).
Prostate Cancer Prevalence
Second to skin cancer, prostate cancer is the most common cancer in men. About 1 in 8 (12.5%) men will receive a prostate cancer diagnosis during their lifetime. Prostate cancer is the second leading cause of cancer death in men, second only to lung cancer. About 1 in 4 men will die from it.
About 6 cases in 10 are diagnosed in men ages 65 or older. Prostate cancer is rarely diagnosed in men under 40. Average age at diagnosis is about 66.
The percentage of prostate cancers diagnosed at the local stage is 74.3%, and the five-year relative survival for localized prostate cancer is 100.0%. The overall five-year relative survival for those diagnosed with prostate cancer is 97.5% (ACS, 2021a; NCI, 2021).
Clinical Manifestations
In most cases, prostate cancer symptoms are not evident in the early stages. About 85% of prostate cancers are detected during early screening tests before the patient develops any symptoms. The severity of symptoms may depend on where the cancer is located in the prostate and how advanced it has become.
Due to the proximity of the prostate gland to bladder and urethra, the cancer may produce a variety of symptoms, including:
- Urinary frequency and urgency
- Dysuria
- Increased urination at night
- Loss of bladder control
- Decreased flow or velocity of urine stream
- Hematuria
- Hematospermia
- Erectile dysfunction
Symptoms in the advanced stage may include:
- Lymphedema in legs or pelvic area
- Numbness or pain in hips, legs, or feet
- Chronic bone pain and fractures
- Weight loss
- Uremic symptoms
(CTCA, 2021b; Johns Hopkins Medicine, 2020)

Diagram showing prostate cancer pressing on the urethra, which can cause symptoms. (Source: Cancer Research UK / Wikimedia.)