Introduction
Prostate cancer is considered a very common solid malignancy after skin cancer. It is also the second to lung cancer as leading cause of cancer-related mortality in U.S. among males. The American Cancer Society (ACS) reported that about 230,110 new cases of prostate cancer occurred in 2004 and that there were about 29,900 related deaths.
Risk and Prevalence
It remains unclear what causes prostate cancer although a number of factors have consistently been associated with increased risk of developing prostate cancer that include:
- Age – According to Office of Population Censuses and Surveys, 80% of diagnosed cases and 93% of deaths from prostate cancer are in men more than 65 years (1996).
- Family history – It is said that the risk in men with either a brother or father affected is doubled (Key, 1995).
- Ethnic origin – Based on actual cases, the incidence is highest among African-Americans and lowest among Asians including Japanese (International Agency for Research on Cancer, 1997) while European men fall into the intermediate category (Dijkman and Debruyne, 1996).
- Androgens – Prostrate cancer initiation and progression are influenced by hormones (Montie and Pienta, 1994).
It is however currently being explored that diet may be a risk factor as prostate cancer is seen among those with diets that have high intakes of fat. Accordingly, there is reduced risk associated in high consumption of vegetables such as tomatoes (Giovannucci et al., 2002) and diets containing fish (Cohen et al., 2000). It was also observed that that diets meeting the recommended daily intake of Vitamin D, Vitamin E and selenium, potentially act as prevention for developing prostate cancer (Dalgleish, 2004).
There are also suggestions that smoking, vasectomy, sexually transmitted diseases, prostatitis, occupational exposure to chemicals and other factors may be considered risk factors but more studies are needed to substantiate the claim.
It was estimated that the overall lifetime risk for a U.S. man to be diagnosed with prostate cancer is between 16% and 17% or roughly 1 in 6 men according to the ACS (2004).In addition, the lifetime risk of dying from prostate cancer is about 3% or 1 in 32 men but the disease can be detected early. More than 75% of cases diagnosed while the disease is still locally confined to the prostate gland leads to greatest possibility to be cured (NCI, 2003).
A lot of studies have shown that dramatic increases in prostate cancer occurred in the mid to late 1980s and highest in 1992. This trend is closely associated with improvement in early detection and the increased use of prostate-specific antigen (PSA) tests in the general population (ACS, 2004; Mettlin&Murphy, 1998; NCI, 2003).
Symptoms
One of the disadvantages of prostate cancer is the lack of obvious or observable symptoms. In cases where symptoms occur, a metastatic state may already have ensued (ACS, 2004; Scher et al., 2000). Many patients diagnosed early with prostate cancer through PSA and DRE tests are considered asymptomatic.
Symptoms include frequent urination mostly at night, frequent pain or stiffness in the lower back, pelvic area or upper thighs, dsyuria or pain or burning sensation on urination, straining on starting urination, weak or interrupted urinary stream, , urinary retention, and sometimes, hematuria or presence of blood in the urine (NCI, 2003; Scher et al.,2000).
Diagnosis
Diagnosis for prostrate cancer is through histologic or cytologic examination of tissue or cells obtained with the use of core needle biopsy or fine needle aspiration (ACS, 2004; Scher et al., 2000).
Others such as transrectal ultrasound (TRUS) are also used in sampling of specimens for histological examination. A TRUS is a small probe inserted into the rectum to allow prostate imaging. It facilitates the sampling of specific zones of the prostate gland where cancer is likely to develop. Sextant biopsy which is the process of obtaining tissue via a needle from a spring-loaded gun may also be conducted from both lobes of the prostate at the apex, a swell as the middle and base of the gland to increase the likelihood of finding cancer (ACS, 2004; Cookson, 2001; NCI, 2003).
Screening
Prostate cancer is detectable by a simple blood test, PSA, and a digital rectal examination (DRE) (Cookson, 2001; Scher et al., 2000). However, it maintains a generally long natural history and a asymptomatic preclinical period. In testing the general population, a PSA value of 4.0ng/Ml is considered the upper limit of normal condition. Cookson (2001) suggested that the criterion value yields a specificity rate of 90% and a sensitivity of 72%.
PSA testing is credited in early detection and diagnosis of prostrate cancer that leads to its cure (Mettlin & Murphy, 1998). PSA screening also led to declines in mortality (Mettlin & Murphy, 1998), but this is still debated until now.
Treatment
Early detection is important for a favorable prognosis and cure (Cookson, 2001; NCI, 2003). Management of early-stage, localized disease is often characterized with two well-established treatments:
- radical prostatectomy or the surgical removal of the prostate
- two forms of radiation therapy (Cookson, 2001; Scher et al., 2000).
One promising form of treatment is the cryotherapy or cryosurgery. It is the process of killing prostate cancer through freezing of the prostate gland (Aus et al, 2002). This however is not yet available to the general public and there is still a need for more knowledge of long-term results. “Watchful waiting” with or without hormone therapy is also recommended for older patients or those with well differentiated or slow growing tumors (Scher et al., 2000). Treatment may be conducted when needed.
References
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Key, T. (1995) Risk factors for prostate cancer. Cancer Surveys23: 63-77.
International Agency for Research on Cancer (1997) Cancer Incidence in Five Continents.
Lyon, France: International Agency for Research on Cancer, World Health Organisation.
Dijkman, G. A., Debruyne, F. M. (1996) Epidemiology of prostate cancer. European Urology 30: 281-295.
Montie, J. E. Pienta, K. J. (1994) Review of the role of androgenic hormones in the epidemiology of benign prostatic hyperplasia and prostate cancer. Urology43: 6, 892-899.
Giovannucci, E., Rimm, E. B., Liu, Y. et al. (2002) A prospective study of tomato products, lycopene and prostate cancer rise. Journal of the National Cancer Institute94: 391-398.
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Dalgleish, A. (2004) Prostate cancer: New approaches to prevention and treatment. Trends in Urology, Gynaecology and Sexual Health9: 2, 22-25.
National Cancer Institute (NCI). (2003). Screening for prostate cancer. Web.
Scher, H.I., Isaacs,J.T., & Zelefsky, M.J. (2000). Prostate cancer. In M.D. Abeloff, J.O.Armittage, A.S. Lichter, & J.E. Niederhuber (Eds.), Clinical oncology (2nd ed., pp. 1823-1884). New York: Churchill Livingstone.
Cookson, M.M. (2001). Prostate cancer: Screening and early detection. Cancer Control, 8(2), 133-140.
Mettlin, C.J., & Murphy, G.P. (1998). Why is the prostate cancer death rate declining in the United States? Cancer, 82(2), 249-251.
Aus, G., Pileblad, E., & Hugosson, J. (2002). Cryosurgical ablation of the prostate: 5-year follow-up of a prospective study. European Urology, 42(2), 133-138.