This article is Part I of a two-part señes. Part II, "Prostate Cancer Elder Alert: Living With Treatment Choices and Outcomes" will appear in the February issue of the Journal of Gerontological Nursing.
The 1999 statistics predict 179,300 new cases of prostate cancer will be diagnosed, mostly in men age 65 and older, and almost 40,000 men will die of the disease (Landis, Murray, Bolden, & Wingo, 1999). Prostate cancer rates doubled and mortality increased by 20% between 1976 and 1994, followed by a 24% decline in incidence between 1992 and 1994. To date there is only speculation about the reasons for the fluctuations in incidence, among them increasing life expectancy, environmental carcinogens, and increasingly sophisticated diagnostic techniques (Haas & Sakr, 1997).
Age is the primary risk factor for prostate cancer, and the ageadjusted incidence rate of prostate cancer among men age 65 and older increased by 82% in a populationbased study derived from Medicare claims data and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program between 1986 and 1991 (Potosky, Miller, Albertsen, & Kramer, 1995). Other factors such as ethnicity, family history, and dietary fat have been identified as additional risk factors for prostate cancer. Sensitive and reliable methods for screening and early detection of prostate cancer exist; yet, questions regarding the costs and benefits of screening in asymptomatic men have been raised (Krahn et al., 1994; Lubke, Optenberg, & Thompson, 1994), as well as questions regarding the costs and benefits of diagnosis and treatment of localized prostate cancer (Fleming, Wasson, Albertsen, Barry, & Wennberg, 1993). Most of the controversies center on the argument that screening of asymptomatic men only leads to the detection and costly treatment of latent tumors that would have remained clinically silent and would have been discovered only on autopsy. However, Walsh (1987) outlined the flaws in such assumptions, and in fact, other studies have shown a significant benefit to treatment compared to watchful waiting (Beck, Kattan, & Miles, 1994; Scardino, Beck, & Miles, 1994). Still, the concern has been raised that available treatments for prostate cancer may diminish quality of life by leaving men impotent and incontinent without significantly increasing survival. Treatments currently available for prostate cancer include:
* Surgery with either radical prostatectomy or nerve-sparing prostatectomy.
* Radiotherapy with either standard external beam or conformai therapy, or interstitial seed implantation.
* Hormone therapy with androgen deprivation therapy or orchiectomy.
* Watchful waiting, which includes careful monitoring until symptoms occur followed by one of the aforementioned therapies.
All of these therapies have a major impact on quality of life. Complications resulting from surgical or radiation interventions range from temporary to permanent and from mild to severe. The most common complications following radical prostatectomy are impotence and stress incontinence, while complications following radiation therapy are impotence, cystitis, and proctitis (Middleton, 1996). Research is needed to evaluate these concerns and to test interventions that may improve quality oí life after prostate cancer therapies.
Figure. Prostate cancer detection by age. Comparison of detection rate at initial screening versus subsequent screens, according to patients' ages. Data from Prostate Cancer Awareness Week, 1992 to 1994. From Crawford (1997).
Because age is a major risk factor for prostate cancer, it is the purpose of this article to inform gerontological nurses, who are providing health care to older men at risk for the disease, about the issues and controversies related to the screening, treatment, and management of prostate cancer. Resources to obtain additional professional and consumer information on these topics are identified.
Assuming a 25-year median survival of men age 50, preliminary epidemiology-based calculations developed from autopsy reports indicate the lifetime risk for developing histologic evidence of prostate cancer is approximately 42% by age 75 (Scardino, Weaver, & Hudson, 1992). The lifetime risk of that cancer becoming clinically significant is 9.5%, and the risk of that cancer resulting in death is 2.9% (Seidman, Mushinski, GeIb, & Silverberg, 1985). This means for every 100 men who develop histologic prostate cancer, 23 will develop clinical cancer, and 7 will die of that cancer (Slawin, Ohori, Dillioglugil, & Scardino, 1995). These calculations may underestimate the lifetime risk for prostate cancer because the other epidemiological factors that may need to enter the equation have, until recently, received only minimal attention because of the belief that prostate cancer is a latent cancer.
Epidemiological investigation of prostate cancer has been complicated further by the heterogeneous nature of the disease, which ranges from an indolent form that may never cause clinical symptoms to an aggressive form that commonly is fatal (Willett, 1995). The relatively little epidemiological work completed in prostate cancer indicates four factors that may be related to the risk of developing prostate cancer: age, ethnicity, family history, and dietary fat.
Data collected through the National Cancer Data Base (NCDB) of the American College of Surgeons Commission on Cancer found the mean age at diagnosis was 72.2 (median = 72.3) for the 14,687 patients diagnosed in 1984. This trend has changed little over time because the 1990 statistics showed the mean and median ages for the 23,183 patients diagnosed that year to be 72.3, with 7.1% of patients diagnosed at age 60 or younger (Mettlin, Jones, Averette, Gusberg, & Murphy, 1993).
The American Cancer Society recommends annual prostate-specific antigen (PSA) testing and digital rectal examination (DRE) begin at age 50 for men who have a life expectancy of at least 10 more years, or at age 45 for men who have a strong familial history of prostate cancer or who are Black (von Eschenbach, Ho, Murphy, Cunningham, & Lins, 1997). Mayo Clinic recommendations for screening men at high risk for prostate cancer include annual PSA testing and DREs beginning at age 40 (Cupp & Oesterling et al., 1993). This is supported by data from Prostate Cancer Awareness Week, where initial screenings detected a surprisingly high number of cancers in men age 40 to 49 (Figure) (Crawford, 1997). However, at a meeting of the American Urological Association, it was suggested that baseline screenings for men at high risk for prostate cancer begin at age 35 (Crawford & DeAntoni, 1995).
The 1997 cancer statistics demonstrated the first decline in overall cancer mortality (Parker, Tong, Bolden, & Wmgo, 1997). However, Black individuals continue to be diagnosed at less favorable stages of disease than White individuals, and they have uniformly lower survival rates for almost every major cancer site except the stomach (Cunningham, 1997). This is evidenced clearly by the fact that prostate cancer accounted for 9.4% of cancer deaths in Black individuals but for only 6.2% of cancer deaths in White individuals in 1993 (Cunningham, 1997).
Mebane, Gibbs, and Horn (1990) report a two to three times higher rate of prostate cancer among Black men younger than age 65. In addition, the proportion of individuals diagnosed with metastatic disease is higher, and the 5-year survival rates are lower in Black men, compared to White men (Steele, Osteen, Winchester, Murphy, & Menck, 1994). Black men have a 9.6% risk of being diagnosed with prostate cancer and a 3% risk of dying of the disease, compared to a 5.2% risk of diagnosis and a 1.4% risk of dying from the disease for White men. For Black men this translates into an 85% greater chance of being diagnosed with prostate cancer and a 114% greater chance of dying from this disease than White men (Morton, 1994).
It has been suggested that there is an increased risk of prostate cancer among men with a family history of prostate cancer. This often is termed "familial" or "hereditary," but the terms actually are not synonymous. Familial prostate cancer is a broader term referring to the simple clustering of the disease within families, whereas hereditary prostate cancer is a more specific term referring to a subtype of familial prostate cancer with a pattern of cancer distribution consistent with Mendelian inheritance of a susceptible gene (Carter et al., 1993).
In a series of men with a family history of a brother or father with prostate cancer, 15% were diagnosed with the disease versus 8% of control individuals who had no affected first-degree relatives (Carter et al., 1993). However, the hereditary variant of prostate cancer only accounts for less than 10% of prostate cancers and mostly for those cancers occurring in men with onset younger than the median age. This information may influence older men with a positive history to share their diagnosis with children and other younger first-degree relatives and to encourage screening at a younger age.
AGE-SPECIFIC PROSTATE-SPECIFIC ANTIGEN REFERENCE RANGES
One of the most important findings for individuals who have familial risk for prostate cancer was the identification of Chromosome 1 as the location of at least one of the genes involved in the familial form of prostate cancer (Smith et al., 1996). Although the gene itself has not been located precisely, researchers with the Center for Human Genome Project are making progress in attempting to map the complete sequence of the 3 billion DNA base pairs and the identification of all human genes by 2005. Implications of genetic testing for prostate cancer for men are similar to those faced by women regarding the identification of the BRCAl gene for breast cancer, and focus mainly on informed consent and confidentiality issues.
Several studies have demonstrated an association between animal fat intake (Graham et al., 1983; Rotkin, 1977), particularly red meat (Giovannucci et al., 1993; Whittemore et al., 1995), and risk of developing prostate cancer. Also, in one study, distribution and amount of body iat has been reported to increase risk of prostate cancer (Hayes et al., 1992). However, the strength of this association is unclear and warrants further investigation.
In an extensive review of the literature, Haas and Sakr (1997) reported that weak associations have been suggested between risk for prostate cancer and the following occupational characteristics:
* Heavy physical labor.
* Rubber manufacturing.
* Newspaper printing.
* Industrial exposure to high levels of cadmium (found in alkaline batteries, paint, and electroplating). However, the duration of exposure associated with increased risk is not known (Elighany et al., 1990; Pienta & Esper, 1993). Similarly, a significantly increased risk of developing prostate cancer was observed in a study of 250,000 veterans who smoked 40 or more cigarettes per day versus those who smoked less than 40 cigarettes per day. The men in this study were followed for more than 20 years, and one theory, although it is unproven, was that tobacco has an effect on sex hormone metabolism, which in turn may have an effect on malignant growth of the prostate (Hsing, McLaughlin, Hrubec, Blot, & Fraumeni, Jr., 1991). Additionally, there is inconclusive scientific support for links between development of prostate cancer and history of gonorrhea, vasectomy, benign prostatic hyperplasia, and hormonal metabolism (Haas & Sakr, 1997).
Results of epidemiological studies guide the development of modifiable risks for prostate cancer that may be biological, behavioral, or environmental in nature. For example, although genetics cannot be altered at this time, individuals with a family history of prostate cancer or individuals in a high-risk group require close surveillance and assistance in maximizing protective mechanisms within their bodies. Research has demonstrated the beneficial effects of certain vitamins, minerals, and nutrients in preventing some cancers; other chemical agents (i.e., chemoprevention) are under investigation. The National Cancer Institute Prostate Cancer Prevention Trial is one major study investigating the role of finasteride (Proscar) as a chemopreventive agent which may prevent or slow the progression of prostate cancer in high-risk individuals, although final results have not been published yet (Guess, Gormley, Stoner, & Oesterling, 1996).
The protective effects of diet on prostate cancer development may be enhanced by:
* Lowering total dietary fat consumption, especially animal fats (Whittemore et al., 1995).
* Ingesting yellow and green vegetables daily (Hirayama, 1979).
* Consuming diets rich in cereals, fruits, tomatoes, beans, peas, and lentils (Pierna & Esper, 1993; Whittemore et al., 1995).
Foods high in fiber and vegetables will assist in altering androgen levels and thereby may assist with retarding the growth of prostate cancer. AU individuals need information about the benefits that can be obtained simply by planning meals with low-fat and high-fiber ingrethents.
There are claims that antioxidants have a protective effect against malignant cells. Antioxidants are molecules found in vitamins that block the action of specific oxygen molecules (i.e., free radicals). Free radicals damage DNA and make cells more likely to become cancerous (Bostwick, MacLennan, & Larson, 1996). Soybean products, whole-grain cereals, berries, seeds, and nuts are purported to have these properties (Adlercreutz, 1995), yet many Americans fail to include them in their diets. It is hypothesized that Vitamin D, in combination with sufficient amounts of sun exposure (Hanchette & Schwartz, 1992), generates a protective mechanism. Vitamin A (i.e., retinoic acid), derived from vegetable sources (Kadman & Thompson, 1996), promotes healthy epithelial cells but may be lacking in individuals' diets. The role of beta carotene, found in leafy green vegetables and carrots, was examined in retrospective studies, and it shows promise in exhibiting protective effects (Van Poppel & Goldbohm, 1995). Inclusion of known antioxidants into individuals' diets will assist them to enhance their bodies' protective mechanisms.
Another behavioral modification to reduce cancer risk is smoking cessation. Although the effects of tobacco on androgen metabolism and prostate cancer are inconclusive (Hsing et al., 1991; Matzkin & Soloway, 1993), the strong link to lung, bladder, and kidney cancers is sufficient to discontinue use.
Currently, the available research results exploring the interaction between environmental factors and prostate cancer are limited to descriptive studies. Further research is needed to determine whether minimizing direct contact with heavy metals such as cadmium and zinc would decrease the incidence or aggressiveness of prostate tumors in exposed individuals
CONTROVERSIES IN SCREENING AND EARLY DETECTION
Programs for screening and early detection of prostate cancer are under scrutiny related to cost effectiveness and quality of life issues. Screening asymptomatic men may lead to detection and costly treatment of latent tumors which would have remained clinically silent and been discovered only on autopsy. Also, available treatments for earlystage prostate cancer diminish quality of life by leaving men impotent and incontinent without significantly increasing survival rates.
RESOURCES TO ASSIST WITH INFORMATION AND TREATMENT
Several recent studies of financial cost and quality of life in clinically asymptomatic men who were diagnosed with elevated PSA and who received prostate cancer therapy demonstrate little or no benefit related to health outcomes (Fleming et al., 1993; Krahn et al., 1994). These studies used cost-utility methods (i.e., a type of cost-effectiveness analysis) to derive ratios reported as dollars/quality adjusted life year ($/QALY). A QALY is a composite measure of health outcomes in which time in a health state is weighted by the quality of that health state (i.e., quality of life). The weight, which is a number between 0 (i.e., death or worst possible health) and 1 (i.e., best possible health), is called a utility. Utility is derived from individual preferences for a condition or health state. Individual preferences are summed, and the ensuing value is used to weight survival or other health outcomes. In a cost-utility analysis, a program may be evaluated and compared to the next best alternative on a $/QALY basis.
These early studies of the cost effectiveness of prostate cancer and its treatment have been criticized for two main flaws: data on disease progression and survival used in the models were obtained from inappropriate populations; and the methods for deriving utility weights were neither standardized nor valid (Benoit & Naslund, 1997). Nonetheless, these studies have caused much controversy, and further research is needed to refute or confirm these findings. Comprehensive cost-benefit studies related to prostate cancer detection, treatment, and accompanying adverse treatment effects currently are in progress and will contribute to decision-making in the future. However, results from these longitudinal studies are not expected for at least 10 years (Chabner, Haluska, & Talcott, 1997).
Information about risks and benefits can play an important role in patient decision-making about screening. In fact one study reported that men who viewed a videotape of the natural course of early-stage prostate cancer, the known risks of treatment, and the uncertainty of survival benefits were more likely to refuse screening than men who did not view the videotape (Flood et al., 1996). Until risks versus benefits are better defined, screening often is conducted. There are two main tests used to screen for prostate cancer: the DRE and PSA testing. Other tests are available, such as transrectal ultrasonography (TRUS), but these are prohibitively expensive for screening and generally are used for diagnostic purposes.
SCREENING AND EARLY DETECTION
Digital Rectal Examination
Although routine screening for prostate cancer was suggested as early as 1905, the first study to report on prostate cancer screening using DRJE (i.e., manual palpation of the prostate via the rectum) occurred in 1971. At that time, Gilbertsen found 75 cancers in 5,856 men screened with DREs for an overall detection rate of 1.3% (Gilbertsen, 1971). Since that time, multiple studies using DREs have been conducted which show the limited ability of DRE alone to detect pathologically localized cancers (Littrup, Lee, & Mettlin, 1992). The American Cancer Society recommends DRE be performed by health care workers skilled in recognizing subtle prostate abnormalities, including those of symmetry and consistency, as well as the more classic findings of marked induration or nodules. Digital rectal examination is less effective in detecting prostate carcinoma compared with PSA testing.
Prostate-Specific Antigen Testing
Prostate-specific antigen, also known as human kallikrien 3 (hK3), is a glycoprotein produced only in the prostate. Initially used as an indicator of disease progression, PSA has come to be used routinely in screening. However, some elevations in PSA may be due to benign conditions of the prostate, and work is ongoing to improve the positive predictive value of this test. A prostate cancer detection rate of 2.2% was reported using PSA testing as the initial screen, with a decision level of 4.0 ng/mL (Catalona et al., 1991). A Canadian study of 1,002 men using a decision level of 3.0 ng/mL determined the sensitivity, specificity, positive predictive value, and negative predictive value of PSA testing to be 80.7%, 89.6%, 24.1%, and 98.6%, respectively (Labrie et al., 1992). Littrup et al. (1992) report the positive predictive value increases to 66% for PSA values limited to 2.1 to 4.0 ng/mL. Based on these reports, Littrup et al. (1992) recommend a prudent screening program including DRE and PSA testing at 4.0 ng/mL, which should produce an estimated sensitivity for the PSA plus DRE combination of 83%. In a review of the screening literature, Slawin et al. (1995) state that screening with DRE and PSA testing detects clinically significant, not latent, prostate cancers at an earlier, more favorable stage.
The positive predictive value of PSA testing has been increased by the recent development of assays to measure several molecular forms of PSA that exist in the serum, including free PSA, PSA complexed to alphal-antichymotrypsin (bound), and total PSA. Knowing the amount and ratio of these molecular forms of PSA can enhance the discrimination of potentially curable prostate cancer from benign prostatic hyperplasia and decrease the number of unnecessary prostate biopsies. The free-to-total PSA ratio appears to have its greatest value for detecting potentially curable prostate cancer with a serum PSA value between 2 and 10 ng/mL (Oesterling et al., 1995).
In addition, other developments to enhance either the sensitivity or specificity of the PSA have been reported, including age-specific PSA values (Table 1); PSA velocity or the rate of change over time (i.e., three PSA values for 2 years); and PSA density or the ratio between prostatic volume and serum PSA, which requires a TRUS (Pannek & Partin, 1997).
IMPLICATIONS FOR GERONTOLOGICAL NURSES
The American Cancer Society Prostate Cancer Detection Guidelines were revised in June 1997 and offer recommendations for health examinations (see the Sidebar on page 10). Nurses need to be aware of the controversies in prostate cancer screening and provide information that will enhance the decisionmaking process and encourage truly informed consent.
The dramatic increase in the rate of prostate cancer is associated, in part, with the increasing use of PSA screening. As technological progress in screening, detection, and treatment of prostate cancer has advanced, widespread dissemination of information about these developments has been evident in the popular press and news media. Older White men, often with supportive encouragement from their spouses or partners or family members, are requesting PSA testing in unprecedented numbers. Men considering screening for early prostate cancer need comprehensive information about positive treatment benefits and the risk of negative outcomes that affect urinary, bowel, and sexual function. In 1996, an expert panel from the American Urological Association concluded radical prostatectomy, radiation therapy, and surveillance are the most appropriate treatment options in the management of clinically localized prostate cancer (Middleton et al., 1995).
Awareness of risk for or a known diagnosis of prostate cancer has many lifestyle implications for men and their partners. Lifestyle choices that may be influenced in an effort to decrease risk of prostate cancer include dietary and activity modifications (see the Sidebar on page 12). The important role partners play in providing emotional and physical support to men at risk for or diagnosed with prostate cancer should be addressed openly by clinical practitioners. Recommendations for men at risk for prostate cancer include dietary adjustments (e.g., decreased saturated fat, increased fiber, low alcohol, balanced diet with increased sources of Vitamins A, C, and D) and lifestyle changes (e.g., regular exercise, smoking cessation, annual physical examination including PSA testing and DRE). These should be discussed with the individuals to increase the likelihood of successful implementation.
Individuals who are choosing from among prostate cancer treatment options need specific information and referrals to sources of specialty medical care where prostate cancer options are discussed routinely. Until more conclusive evidence is available, clinical practitioners who provide primary health care and counseling to men at risk for prostate cancer need to provide information and resources (Table 2) about maintaining healthy lifestyles and the risks and benefits associated with treatment options for prostate cancer based on available data. Providing individuals with clearly written information about healthy low-fat diets, exercise, and smoking cessation will help reinforce the healthy lifestyle recommendations and offer health benefits to the individuals. Healthy lifestyle educational materials are available through the National Cancer Institute and the American Cancer Society. The "Five a Day" campaign from the National Cancer Institute has many detailed dietary instruction pamphlets that specify how to incorporate antioxidant-rich foods into the daily diet. Down Home Healthy: Family Recipes of Black American Chefs is a publication of the National Cancer Institute (1993) that offers low-fat recipes for Black families. Copies of educational pamphlets may be obtained by contacting the National Cancer Institute at (800) 4-CANCER and the American Cancer Society at (800) ACS-2345.
In addition to the clinical implications for nurses, there are research opportunities in the study of the epidemiology, screening, and early detection of prostate cancer. This work continues to help nurses better understand the epidemiology of the disease. Research into areas such as gene-environment interactions is just beginning. Areas specifically suited for nursing interventions, including education, implementation, and counseling of men regarding genetic testing of prostate cancer, are rapidly growing interests. Clinical trials to determine the survivai benefits of prostate cancer screening are underway and need to be linked with studies of the cost effectiveness of screening and early detection.
As the United States prepares to meet the aims outlined in Healthy People 2010 (U.S. Department of Health and Human Services, 1999), a clear disease prevention and health promotion agenda emerges. Prostate cancer is a highly curable disease, and older men benefit from prevention, early detection, and health promotion activities provided by gerontological nurses.
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AGE-SPECIFIC PROSTATE-SPECIFIC ANTIGEN REFERENCE RANGES
RESOURCES TO ASSIST WITH INFORMATION AND TREATMENT