The Prostate Cancer Outcomes Study (PCOS) was initiated in 1994 by researchers at the National Cancer Institute (NCI) to look at the impact that treatments for primary prostate cancer have on the quality of life of patients. PCOS is a collaboration with six cancer registries that are part of NCI's Surveillance, Epidemiology, and End Results (SEER) Program. (The SEER Program was established by NCI in 1973 to collect cancer data on a routine basis from designated population-based cancer registries in various areas of the country.)
PCOS is the first systematic evaluation of health-related quality-of-life issues for prostate cancer patients conducted in diverse healthcare settings and provides a model for similar large follow-up studies with other cancers. It is expected that better knowledge of the effects of treatment will help patients, families, and clinicians make more informed choices about treatment alternatives. PCOS will also provide some of the most detailed data collected to date on the patterns of prostate cancer care.*
The results of PCOS will be published in various medical journals over the next few years. Those already published are listed at the end of this fact sheet.
Prostate cancer is the single most common form of non-skin cancer in men in the United States. In the year 2000, an estimated 180,400 men will be diagnosed with prostate cancer, and some 31,900 will die of the disease. Prostate cancer exacts a particularly high toll on African-American men; mortality rates in African-American men are more than twice as high as rates in white men.
|Prostate Cancer Statistics
Estimated new cases, 2000: 180,400
Estimated deaths, 2000: 31,900.
Median age for developing disease: 71
Trends: Death rates
Black men: After 1993, lower by
2.3 percent per year on average.
White men: After 1994, lower by
4.6 percent per year on average.
One of the problems facing prostate cancer patients is the uncertainty of many issues surrounding the management of the disease. It is not known, for instance, if the potential benefits of prostate cancer screening outweigh the risks, if surgery is better than radiation, or if treatment is better than no treatment in some cases.
Decisions about treatments are not easy to make. One problem is that it is difficult for a physician to predict whether a tumor will grow
slowly with no health consequences to the patient, or will grow quickly and become life-threatening. Also, there are no randomized trials that compare the relative benefits of treating early stage patients with radiation therapy, radical prostatectomy (surgical removal of the entire prostate gland along with nearby tissues), or watchful waiting (following the patient closely and postponing aggressive therapy unless symptoms of the disease progress). About 80 percent of men diagnosed with prostate cancer have early stage disease.
In spite of all of these uncertainties, it is known that certain treatments -- radiation therapy, radical prostatectomy, or hormonal therapies -- can have detrimental effects on urinary, bowel, and sexual functions. By collecting comprehensive data on the health outcomes of various treatments for prostate cancer, the PCOS will help patients, their families, and physicians make decisions about treatment options.
The Prostate Cancer Outcomes Study uses an already existing population from the NCI SEER tumor registry system. About 3,500 men from six NCI SEER cancer registries including Connecticut, Utah, New Mexico, and the metropolitan areas of Atlanta, Ga., Los Angeles, Calif., and Seattle, Wash., are participating in the study. All of the men were diagnosed with primary invasive prostate cancer from Oct. 1, 1994, though Oct. 31, 1995; their tumors were biopsied.
Eighty-eight percent of the patients were diagnosed with clinically localized disease; 4 percent had evidence of cancer in other organs. Forty-two percent of the men were treated with radical prostatectomy, 24 percent with radiotherapy, 13 percent with hormonal therapy, and 22 percent were not treated.
One of the unique features of this study is that the participants represent a large community-based group of patients from diverse racial and ethnic backgrounds treated in a broad range of health care settings. In contrast, most previous studies lacked racial and ethnic diversity and were limited to a small number of men treated in large cancer centers or academic institutions.
A survey questionnaire was sent to patients at six, 12, 24, and 60 months after the initial diagnosis. The survey was designed to focus on quality-of-life issues -- urinary, sexual, andbowel dysfunctions -- known to be the most relevant to men with prostate cancer.
A unique aspect of the PCOS data collection was the extensive effort made to obtain information from medical records of the patients not routinely collected by SEER. These included specific diagnostic procedures, prostate-specific antigen (PSA) values, clinical stage and grade of tumor, details of treatments including specific hormonal therapies, and acute complications of therapies.
Using the medical records and surveys of the prostate cancer patients, the following PCOS analyses have been published:
- Men with clinically localized prostate cancer who are treated with radical prostatectomy are more likely to experience urinary and sexual dysfunction than those treated with external beam radiation therapy. Bowel dysfunction, on the other hand, is more common among men receiving external radiation therapy.
Of the 1,591 men ages 55 to 74 who were treated for localized prostate cancer and followed for two years, those receiving radical prostatectomy (1,156) reported more urinary incontinence (9.6 percent vs. 3.5 percent), and were more bothered by incontinence (11.2 percent vs. 2.3 percent) than men receiving radiotherapy (435). More men treated with prostatectomy also reported being impotent (79.6 percent vs. 62.5 percent), and among men ages 55 to 59 years, the prostatectomy patients were more bothered by their loss of sexual function than were the radiotherapy patients (59.4 percent vs. 25.3 percent). In general, men in the radical prostatectomy group recovered some urinary and sexual function during the second year after treatment, while men in the radiotherapy group remained the same or became slightly worse.
Two years after treatment, men receiving radiotherapy reported more diarrhea (37.2 percent vs. 20.9 percent) and bowel urgency (35.7 percent vs. 14.5 percent) than did men receiving radical prostatectomy. In general, prostatectomy had very little effect on bowel function while radiotherapy patients experienced a decline in bowel function within the first four months of receiving treatment and recovered some function over the two years.
No clear difference in emotional and mental health or overall physical health status was seen between the two groups.
Reference: Potosky AL, Legler J, Albertsen PC, Stanford JL, Gilliland FD, Hamilton AS, et al. Health outcomes after radical prostatectomy or radiotherapy for clinically localized prostate cancer: Results from the Prostate Cancer Outcomes Study (PCOS). J Natl Cancer Inst 2000;92:1582-1592.
- Radical prostatectomy causes significant sexual dysfunction and some decline in urinary function.
At 18 months or more after surgery, at least 8.4 percent of the patients were incontinent (lost urinary control) and at least 59.9 percent were impotent (unable to achieve an erection sufficient for sexual intercourse). At 24 months, 8.7 percent of men were bothered by the lack of urinary control; 41.9 percent reported that sexual function was a moderate-to-big problem. Nevertheless, most men were satisfied with their treatment choice.
Reference: Stanford JL, Ziding F, Hamilton AS, et al. Urinary and sexual function after radical prostatectomy for clinically localized prostate cancer. JAMA 2000;283:354-360.
- A small percentage of newly diagnosed prostate cancer cases show evidence of metastases with imaging techniques -- bone scans, computerized tomography (CT), and magnetic resonance imaging (MRI).
Less than 5 percent of the imaging studies done for newly diagnosed prostate cancer patients showed evidence of metastases. Specifically, less than 5 percent of men with PSAs between four and 20 showed positive bone scans and less than 2 percent of men with Gleason scores of six or less had positive scans. However, for men with serum PSA levels greater than 50ng/ml and Gleason scores ranging from eight to 10, the imaging studies were positive in over 60 percent of the cases.
Reports show that physicians order bone scans for approximately two-thirds of all new patients and CT exams for about one-third of new patients. The low positive yields led the authors to question the cost-effectiveness of ordering imaging for the majority of men with newly diagnosed prostate cancer.
Reference: Albertsen PC. The positive yield of imaging studies in the evaluation of men with newly diagnosed prostate cancer: a population based analysis. J Urology 2000;163:1138-1143.
- Three factors were found to be the best predictors of the spread of the disease outside the prostate: PSA levels, Gleason score, and age.
The authors were looking for clinical information that could predict the spread of prostate cancer outside the capsule that encases the prostate gland (extracapsular extension**) in men who were diagnosed with localized prostate cancer (by biopsy) and treated by radical prostatectomy; 1,395 men participated in this study.
The researchers found that the strongest predictors of metastasis were high level of PSA, high Gleason score***, and age greater than 70. They reported that men older than 70 with PSAs greater than 20ng/ml, and a Gleason score of eight to 10, had an 85 percent chance of having cancer outside the prostate gland. In contrast, men younger than 50 with PSAs less than 4ng/ml, and a Gleason score less than seven, had a 24 percent chance of having cancer outside the prostate gland. PSA was the strongest single predictor. Ethnicity and region of the country were not useful for predicting metastases.
Because only about half of the men with clinically localized disease undergoing radical prostatectomy had extracapsular extension, many patients may be subjected to the risks and complications of surgery without having a realistic possibility of cure. They also pointed out that physicians may need to reconsider the widely held view that Gleason score is the most important clinical indicator of prognosis.
Reference: Gilliland FD, Hoffman RM, Hamilton A, et al. Predicting extracapsular extension of prostate cancer in men treated with radical prostatectomy: results from the population based prostate cancer outcomes study. J Urology 1999;162:1341-1345.
Several ongoing analyses are examining:
- Health outcomes and quality of life following radiation therapy by age and race and type of radiation therapy.
- The effects of different hormonal therapies on sexual function and general quality of life.
- Factors associated with racial/ethnic differences in diagnosis of advanced stage prostate cancer.
- Factors associated with the use of different initial therapies for clinically localized prostate cancer.
- Treatments used for sexual dysfunction after therapy for localized disease.
* A more detailed description of PCOS is available in the following publication: Potosky AL, Harlan LC, Stanford JL, et al. Prostate Cancer Practice Patterns and Quality of Life: the Prostate Cancer Outcomes Study. J Natl Cancer Inst 1999;91:1719-1724.
** Extracapsular extension is defined as stage T3 or T4 tumor, positive regional lymphnodes, and tumor at the margin of the excised tumor or metastases.
*** The Gleason score is a method of grading the degree of differentiation of a tumor. If a cancer is poorly differentiated (looks like an immature cell), it is likely to be more aggressive; a well differentiated cell looks more similar to a normal cell and is usually less aggressive. The Gleason grade for each reading can range from one to five, with one being the most well differentiated and five being the most poorly differentiated. A pathologist will look at the two most poorly differentiated parts of the tumor and grade them. The Gleason score is the sum of the two grades, and so can range from two to 10. The higher the score, the poorer the prognosis.