What is prostate cancer?
Prostate cancer is the uncontrolled growth of cells in the prostate, a small, walnut-shaped gland that encircles the upper urethra in men and produces a fluid that makes up part of semen. The prostate gland consists of several types of cells, but almost all prostate cancers begin in the cells that produce the prostate fluid (gland cells). These cancers are called adenocarcinomas.
Prostate cancer is the most common cancer in men after skin cancer. According to the American Cancer Society, about 220,800 new cases of prostate cancer will be diagnosed in the United States in 2015 and as many as 27,540 men will die of it.
The risk of developing prostate cancer varies with ethnicity, with African American men at the highest risk. Risk is also elevated in men with a family history of the disease and increases in general as men age. More than 60% of all prostate cancers are diagnosed in men over the age of 65.
Cancer that develops in the prostate may stay localized (entirely contained within the prostate) for many years and cause few noticeable symptoms. Most cases of prostate cancer are slow-growing, and symptoms begin to emerge only when the tumor mass grows large enough to constrict the urethra. This can cause symptoms such as:
- Frequent urination, especially at night
- A weak or interrupted urine stream
- Pain or burning upon urination or ejaculation
- Pus or blood in urine or semen
- Discomfort in the lower back, pelvis, or upper thighs
Many of these symptoms, however, can also be caused by other conditions, such as benign prostatic hyperplasia (BPH), a urinary tract infection (UTI), acute prostatitis, or a sexually transmitted disease.
BPH is a non-cancerous enlargement of the prostate that is very common in men as they age. According to the American Urological Association, it can affect as many as 90% of men by the time they are 80 years old. It does not cause prostate cancer, but both may be found together. Through testing, healthcare providers must determine whether a man's symptoms are due to prostate cancer, BPH, or to another non-cancer-related condition. This may involve a PSA test and digital rectal exam (DRE) and, depending on the results of those, a prostate biopsy.
Men who have no symptoms must decide, along with their healthcare providers, whether to undergo screening for prostate cancer. Many organizations, such as the American Cancer Society and the American Urological Association, recommend that men discuss the advantages and disadvantages of PSA-based screening for prostate cancer with their healthcare provider before making an informed decision about whether to be screened or not, However, some organizations, such as the U.S. Preventive Services Task Force, feel that the harms associated with over-diagnosis and over-treatment outweigh the potential benefits and advise against using PSA to screen for prostate cancer in healthy men of any age.
One important factor to consider when deciding whether to undergo screening is personal risk of developing prostate cancer:
- Average risk—includes healthy men with no known risk factors
- Increased risk—African American men or men who have a father or brother who was diagnosed before they were 65
- High risk—includes men with more than one relative who was affected at a young age
For men who wish to be screened for prostate cancer, the American Cancer Society recommends that healthy men of average risk consider waiting to get tested until age 50, while the American Urological Association recommends screening for men between the ages of 55 and 69 with no routine screening after age 70.
For those at high risk, such as American men of African descent and men with a family history of the disease, the recommendation is to consider beginning testing at age 40 or 45.
While elevated PSA levels are associated with cancer, they may be caused by other conditions, such as BPH and inflammation of the prostate. Since a PSA test can be elevated temporarily for a variety of reasons, a repeat PSA may be done a few weeks after an initially elevated one to determine if it is still elevated. If the repeat test is elevated, a healthcare provider may recommend that series of PSAs be done over time to determine whether the level goes down, stays elevated, or continues to increase.
An elevated PSA may be followed by a biopsy, which has risk of complications such as pain, fever, blood in the urine, or urinary tract infection. (Read the article on Anatomic Pathology for more information about biopsies.) If prostate cancer is diagnosed, it must also be determined whether it is clinically significant. If a prostate cancer is small, localized, and slow-growing, it may never cause significant health problems.
There is a saying that "many men die with prostate cancer, not from it." In these cases, the treatments may sometimes be worse than the cancer as they can cause side effects such as erectile dysfunction and incontinence. In cases where the cancer appears to be slow-growing, the healthcare provider and patient may decide to monitor its progress rather than pursue immediate treatment (called "watchful waiting").
Some prostate cancers, however, do grow and spread aggressively into the pelvic region and then throughout the body; and some slow-growing cancers eventually become large enough and troublesome enough that they require medical intervention. The challenge is to detect prostate cancer, evaluate its growth rate and spread, and for the patient and his healthcare provider to decide which treatment courses to follow and when.