Prostate Cancer Chapter 6
What Is Prostate Cancer?
What Is Cancer?
The process of cell growth in the body is normally an orderly one. Cells grow and divide as necessary to produce more cells as they are needed. Cells that are old or damaged die, and are replaced with new cells.
In cancer, something has gone wrong with this process. The cell's DNA has been damaged. DNA is a substance found in every cell in the body that directs the cell's functioning and reproduction. Cell DNA may be damaged by environmental agents, such as radiation (including excessive sunlight), viruses, chemicals, and tobacco smoke. Cells with damaged DNA may also be inherited from one's parents.
Normally, if a cell has damaged DNA, it either repairs it or dies. But in cancer, the damaged cell starts to reproduce in an uncontrolled way, creating more abnormal cells. It outlives the normal cells around it and forms a tumor (a lump or mass).
Not all tumors are invasive. Benign tumors may simply be removed and are unlikely to grow back again. Malignant tumors, however, are cancerous, and they may start to invade surrounding tissues. By entering the bloodstream or the lymph system, cancer cells can spread throughout the body.
Types of Cancer
Cancer is not one disease. There are more than one hundred different types of cancer, and they all behave differently. Liver cancer, for instance, grows at a different rate than colorectal cancer, and responds to different treatments.
Cancer is named after the site where it originates, no matter where it spreads. Breast cancer that has spread to the lungs is termed metastatic breast cancer, not lung cancer. Although there are many different types of cancer, they can all be divided into five main categories:
- Carcinoma. Cancer that begins in epithelial cells (cells that form the skin or tissues that line or cover internal organs)
- Sarcoma. Cancer that begins in connective tissue (such as bone, cartilage, fat, muscle, and blood vessels)
- Leukemia. Cancer that starts in blood-forming tissue (like bone marrow)
- Lymphoma and myeloma. Cancers that begin in the cells of the immune system
- Central nervous system cancers. Cancers that begin in the tissues of the brain or spinal cord
About 80-95% of all cases of prostate cancer are carcinomas that develop in the glandular tissue of the prostate. This type of cancer is referred to as prostatic adenocarcinoma. (Adenocarcinomas are carcinomas that originate in glandular tissue.) Approximately 4% of cases of prostate cancer are thought to begin in the lining of the prostatic urethra. Of all prostate cancer cases, 70-75% develop in the peripheral zone, 15-20% develop in the central zone, and 10-15% develop in the transition zone. The peripheral zone contains about two-thirds of the glandular tissue of the prostate. The cancer cells may extend through parts of one or both lobes of the gland.
Most cases of prostatic adenocarcinoma grow more slowly than most other types of cancer. In fact, some prostate tumors grow so slowly that they never require treatment. Autopsy studies have shown that many older men who died of other causes also had prostate cancer that never caused a problem during their lives. According to these studies, 70-90% of men may have prostate cancer by the age of 80, and not know it. Because of this, some doctors feel that a watchful-waiting or active-surveillance approach is justified for small prostate tumors that are well differentiated; that is, the cancer cells look very similar to normal cells. However, some forms are aggressive and can spread quickly. Prostate cancer that is detected early has a better chance of successful treatment.
Extracapsular extension refers to the point at which the prostate cancer cells have extended into, and possibly through, the prostate capsule (the outer lining of the prostate gland). The cancer cells may extend through parts of one or both lobes of the gland. Extracapsular extension does not mean the same thing as metastatic cancer.
Who Gets Prostate Cancer?
Prostate cancer almost always occurs in men over the age of 40 and is extremely rare in men who are under that age. The older a man is, the more chance he has of developing prostate cancer. Men of African descent and men who have a family history of prostate cancer have a higher risk of developing prostate cancer than do men of other races or men without a family history of the disease.
Benign Prostatic Hyperplasia (BPH)
Benign prostatic hyperplasia (BPH), also known as benign prostatic hypertrophy or enlarged prostate, is the noncancerous growth of the prostate gland. BPH is very common: in the US, most men over the age of 60 have the disorder. The prostate can become quite large due to BPH. A moderately enlarged prostate is about the size of a large plum, a very enlarged prostate is about the size of an apple, and an extremely enlarged prostate can be the size of a grapefruit.
What Causes BPH?
The cause of BPH is unknown. On theory holds that as a man ages, the ratio of male (testosterone) to female (estrogen) hormones changes, and this change stimulates the prostate to grow. Another theory is that over time the prostate gland becomes more sensitive to normal levels of testosterone and grows more rapidly.
Whatever the cause, beginning around age 40 the prostate begins to enlarge, more in some men than in others. Two types of tissue are involved: glandular tissue and smooth muscle tissue. As the glandular tissue grows, it can compress the urethra and partially or completely block urine flow. The smooth muscle tissue reacts to this growth by tightening around the urethra, making it difficult for the urethra to relax and allow urine to flow. In either case, urine flow is impeded and the bladder doesn't empty completely during urination.
Symptoms of BPH
Symptoms of BPH can include:
- Difficulty urinating
- Needing to urinate frequently
- Weak urine stream
- Stopping and starting again while urinating
- Increased frequency of urination at night (nocturia)
- Urgent need to urinate
- Not being able to completely empty the bladder
- Blood in the urine (hematuria)
- Urinary tract infection (UTI)
Complications of BPH
The complications of BPH can be severe:
- Acute urinary retention (AUR), the sudden painful inability to urinate. A catheter must be inserted into the bladder through the penis to drain the urine.
- UTIs inflame the urethra and bladder and cause painful urination.
- Bladder stones are mineral deposits that can obstruct urine flow and cause infection, bladder irritation, and hematuria.
- Bladder damage can occur when, over a long period of time, the bladder doesn't empty completely during urination. The bladder wall of the bladder stretches, weakens, and can no longer contract properly.
- Kidney damage can be caused by frequent infections and by urinary retention. Men who have obstructed urine flow due to BPH are three times more likely to have chronic kidney disease.
No one knows the exact cause of prostate cancer, but there are known risk factors for the disease. A risk factor for prostate cancer is anything that increases a man's chance of developing the disease, even though the risk factor may not directly cause it. Some men with many risk factors never get prostate cancer, while others with no risk factors do develop it. Some risk factors for prostate cancer are controllable, and some aren't. If you know you have risk factors for the disease, screening may be for you. Be aware, though, that screening for prostate cancer is a controversial subject. Screening does improve detection of aggressive cancer that requires treatment, but it also increases detection of slow-growing cancer that will probably not require treatment during a man's lifetime.
Risk factors for prostate cancer include:
- Age. Age is the strongest risk factor for prostate cancer. Risk of prostate cancer rises rapidly after age 50.
- Race. Prostate cancer is a major public health problem for men of African descent. African-American men are more likely than men of other races to develop prostate cancer at an earlier age, to have aggressive tumors that grow quickly, to have more advanced disease when it is found, and to die of the disease. Prostate cancer also occurs more often in non-Hispanic white men than it does in Asian-American and Hispanic/Latino men. The reasons for these racial differences are not clear.
- Lifestyle. Prostate cancer is most common in the US, Australia, New Zealand, and Western and Northern Europe. The lowest rates are in East and South Central Asia. The reasons for these differences are not clear, although diet appears to be a factor (see below).
- Family history. Men who have fathers or brothers with prostate cancer have a higher risk of developing the disease than men who don't.
- Genetics. Several inherited genes have been found that seem to raise prostate cancer risk, but they probably account for only a small number of cases. More research remains to be done in this area.
- Diet. A diet high in fat, especially animal fat, may increase prostate cancer risk.
- Hormones. High levels of testosterone, a male sex hormone, may cause or accelerate the growth of prostate cancer. Men who are on testosterone therapy are therefore more likely to develop prostate cancer than men who have lower levels of testosterone.
In addition to the above known risk factors, some studies have found the following factors linked to prostate cancer. However, at this point the data isn't conclusive and more research is needed.
- Lack of exercise
- Infection and inflammation of the prostate
Urinary symptoms of advanced prostate cancer can include:
- Difficulty urinating, burning sensation, starting and stopping while urinating, frequent urination, blood in the urine, incontinence, and decreased force in the stream of urine. However, these symptoms are more often caused by noncancerous conditions, such as BPH or prostate infections. Less than 5% of prostate cancer cases have urinary problems as the initial symptom.
Late-stage general symptoms can include:
- Blood in the semen
- Pain with ejaculation
- Swelling in the legs
- Pain with bowel movement
- Discomfort in the pelvic area
- Pain in one or more bones
- Bone fractures
- Compression in the spine
- Chronic pain in the spine
- Pain in the pelvis, lower back, hips, or thigh bones
- Unintended weight loss
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The material on this site is for informational purposes only and is not intended as medical advice. It should not be used to diagnose or treat any medical condition. Consult a licensed medical professional for the diagnosis and treatment of all medical conditions and before starting a new diet or exercise program. If you have a medical emergency, call 911 immediately.