Doctor's Notes on Prostate Cancer
Prostate cancer is a disease in which cells in the prostate gland, a part of the male reproductive system, start to multiply uncontrollably. Prostate cancer cells can also spread (metastasize) to other organs and tissues in the body, commonly the pelvic lymph nodes and bones. Less commonly prostate cancer cells may also metastasize to the lungs and liver.
Most men will have no symptoms of prostate cancer, especially in the early stages. When they do occur, symptoms of prostate cancer are typically due to urinary blockage at the bladder neck or the urethra and may include difficulty in starting and stopping urination, increase in frequency of urination, pain while urinating, urinary retention, and a feeling of bladder fullness after urination. When the blockage is chronic, recurring urinary tract infections (UTIs) may occur. Rare symptoms of advanced prostate cancer may include blood in the urine, painful ejaculation, and impotence. If prostate cancer has spread, symptoms may include fatigue, feeling unwell (malaise), and weight loss. Metastasis to the bones can cause deep bone pain.
Prostate Cancer Symptoms
Most men with prostate cancer have no symptoms.
- This is particularly true of early prostate cancer. Symptoms usually appear when the tumor causes some degree of urinary blockage at the bladder neck or the urethra.
- The usual symptoms include difficulty in starting and stopping the urinary stream, increase in frequency of urination, and pain while urinating. These symptoms are commonly referred to as “irritative” or “storage” urinary symptoms.
- The urinary stream may be diminished (urinary retention), or it may simply dribble out and a feeling of bladder fullness after urination can appear as well. These symptoms are commonly referred to as “voiding” or “obstructive” urinary symptoms.
- It is noteworthy that these symptoms, by themselves, do not confirm or necessarily reflect the presence of prostate cancer in any single individual. Indeed, most, if not all of these can occur in men with noncancerous (benign) enlargement of the prostate (BPH), which is the more common form of prostate enlargement. However, the occurrence of these symptoms should prompt an evaluation by a physician to rule out cancer and provide appropriate treatment.
- If the cancer causes a chronic (long-term) or more advanced obstruction, the bladder may be affected and be more prone to recurring urinary tract infections(UTI).
- Rare symptoms that may manifest occasionally when the cancer is advanced may include blood in the urine (hematuria), painful ejaculation, and impotence (inability to have an erection).
- If the cancer has spread to remote organs (metastasis) symptoms may include fatigue, malaise, and weight loss. Metastasis to the bones can cause deep bone pain, particularly in the hips and back or even bone fractures from weakening of the bone.
Prostate Cancer Causes
The specific cause of prostate cancer remains unknown. Hormonal, genetic, environmental, and dietary factors are thought to play roles. Yet, the only well-established risk factors for prostate cancer are age, ethnicity, and heredity.
- Age: There is a strong correlation between increasing age and developing prostate cancer. The incidence of prostate cancer increases steadily as men grow older. The median age at diagnosis of prostate cancer is 70.5 years of age. Most prostate cancers are diagnosed in men older than 65 years of age. Autopsy records indicate that a majority of men older than 90 years of age have at least one region of cancer in their prostate.
- Ethnic origin: In the U.S., African American men are more likely than Caucasian men to develop prostate cancer. They are also more likely to die from this disease as compared to Caucasian men of a similar age. Asian Americans, on the other hand, have a much lower chance of getting prostate cancer as compared to Caucasians or African Americans. Internationally, Caucasian men from Scandinavian countries experience the highest rates whereas men from Asia the lowest. Although, these ethnic criteria have been used to study and describe the disease in the past, there is no defined biologic basis for this classification. In other words, these differences in diagnosis and death rates are more likely to reflect a difference in factors like environmental exposure, diet, lifestyle, and health-seeking behavior rather than racial susceptibility to prostate cancer. Recent evidence, however, suggests that this disparity is progressively decreasing with high chances of complete cure in men undergoing treatment for organ-confined prostate cancer (cancer that is limited to within the prostate without spread outside the confines of the prostate gland) irrespective of race.
- Family history: Men who have a history of prostate cancer in their family, especially if it is a first-degree relative such as a father or brother, are at an increased risk of developing prostate cancer. If one first-degree relative has prostate cancer, the risk is at least doubled. If two or more first-degree relatives are affected, the risk increases by 5- to 11-fold.
- Diet: Dietary factors may influence the risk of developing prostate cancer. Specifically, total energy intake (as reflected by body mass index) and dietary fat have been incriminated. In addition, there is some evidence that suggests that obesity leads to an increased risk of having a more aggressive, larger prostate cancer, which results in a poorer outcome after treatment. Nevertheless, the question remains whether there is enough evidence to recommend lifestyle changes specifically to prevent prostate cancer independently of the known health and cardiovascular benefits.
- Infection: Recent evidence has suggested the role of sexually transmitted infections as one of the causative factors for prostate cancer. People who have had sexually transmitted infections are reported as having 1.4 times greater chance of developing the disease compared to the general population.
- Cadmium: Exposure to chemicals such as cadmium may be implicated in the development of prostate cancer.
- Selenium and vitamin E: While initial reports of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) found no reduction in risk of prostate cancer with either selenium or vitamin E supplements, recent conclusions confirmed that vitamin E not only fails to prevent prostate cancer but actually increases prostate cancer risk. In this study, men who took vitamin E supplement 400 IU per day had a 17% increase in their risk of the disease. Therefore, patients should be advised not to take vitamin E supplement.
- Vitamin C: Vitamin C 500 mg PO every other day did not reduce the incidence of prostate cancer in the Physicians' Health Study-II (PHS II) after a median follows up of 8 years. Therefore vitamin C should not be recommended to prevent prostate cancer.
Factors not associated with prostate cancer:
- Benign prostatic hyperplasia (BPH): Prostate cancer does not appear to be related to benign prostatic hypertrophy (BPH); however, BPH increases the risk of a high PSA, which may lead incidentally to a diagnosis of disease.
- Vasectomy: Vasectomy is not a risk factor for prostate cancer.
- Sexual activity: There is no proven link between frequency of sexual activity and prostate cancer risk.
Prostate cancer is the development of cancer cells in the prostate gland (a gland that produces fluid for semen). It is the most common cancer in men; some cancers grow very slowly while others are very aggressive and spread quickly to other organs.
How Does Prostate Cancer Develop?
Like all cancers, prostate cancer begins when a mass of cells has grown out of control and begins invading other tissues. Cells become cancerous due to the accumulation of defects, or mutations, in their DNA.
Most of the time, cells are able to detect and repair DNA damage. If a cell is severely damaged and cannot repair itself, it undergoes so-called programmed cell death or apoptosis. Cancer occurs when damaged cells grow, divide, and spread abnormally instead of self-destructing as they should.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.