Urologists Play Key Role in Deciding Use of Hormone Therapy in Prostate Cancer
Doctor's preference, not disease stage, often dictates this decision, study says
June 21, 2006 - The urologist a prostate cancer patient sees may be a more important factor than the stage or grade of the patient's' cancer in deciding whether (or when) the patient will be started on androgen deprivation therapy, a new study reports in the June 21 issue of the Journal of the National Cancer Institute.
Androgen deprivation therapy, which blocks male sex hormones called androgens, is used in around 50% of prostate cancer patients. It is recommended for locally advanced and metastatic prostate cancer. Because the therapy is expensive and has multiple side effects affecting general health and quality of life, it is important to understand the factors responsible for its use.
A team led by Vahakn B. Shahinian, M.D. at the University of Texas Medical Branch in Galveston examined the medical records of nearly 62,000 men on Medicare who were diagnosed with prostate cancer at age 65 years or older. Dr. Shahinian (who is a nephrologist) also looked at records of the patients' 1,802 urologists to assess how often each urologist had prescribed androgen deprivation in his or her practice in the six months prior to treating an individual patient enrolled in the study.
The researchers tracked the pattern of androgen therapy use to see what drove this decision to start androgen blockade -- urologist decision versus patient and tumor characteristics.
They found that use of androgen deprivation therapy for prostate cancer was more dependent on the urologist who treated the patient than on characteristics of the tumor or patient.
Fewer than ten per cent of patients, the authors say, received androgen blockade because of the nature of their prostate cancer (tumor characteristics of stage or grade). About five percent of patients were put on this therapy because of some factor categorized as "patient characteristics" not always disease-related (age, ethnicity, socio-economic status, prexisting illness in addition to the cancer, geographic region, or year of diagnosis). Twenty percent or more of the total variance in use of androgen deprivation therapy was attributable to the urologist.
The authors write, "The substantial variance in use of androgen deprivation therapy attributable to the urologist, independent of patient factors, suggest that interventions at the level of the urologist may be an effective way to modify the use of this therapy for prostate cancer."
Dr. Shahinian has previously published a study that found that after taking androgen deprivation therapy for prostate canc, men suffer an increased risk of fractures (NEJM, January 13, 2005).
In an accompanying editorial, Paul F. Schellhammer, M.D., Professor of Urology at Eastern Virginia Medical School in Norfolk, Va., says:
The variance attributed to the physician was higher for androgen deprivation therapy than for other diseases or physician practices studied, such as care of diabetic patients or prescription of beta-blockers. It is also important that the decision to use androgen deprivation therapy be appropriate because androgen deprivation therapy is the second highest Medicare Part B expenditure ($1.2 billion in 2003) and because adverse effects of this treatment reduce quality of life. If urologists direct use of this therapy, their decisions should be appropriate and evidence based.
Schellhammer pinpoints a problem with the study's method, namely, failure to distinguish between more and less aggressive Gleason 7 grade tumors. He writes:
My concerns about the accuracy of the assumptions made about grade and PSA are as follows. The authors note that their grade distributions are obtained from the patient's records, in which tumor grade is recorded as a Gleason sum. A Gleason sum of 2, 3, or 4 is translated to a well-differentiated tumor; a sum of 5, 6, or 7 to a moderately differentiated tumor; and a sum of 8, 9, or 10 to a poorly differentiated tumor according to the protocol of the SEER database. The translation of a Gleason sum of 5, 6, or 7 to a moderately differentiated or intermediate-risk category may be problematic because it mixes clearly low-risk disease (represented by a Gleason sum of 5 or 6) with more aggressive disease (represented by a Gleason sum of 7). A Gleason sum of 7 can trend to intermediate or high-risk disease, depending on the preponderance of pattern 4.
Therefore, the ... intermediate or moderately differentiated categoryÂindeed, 35 536 case patients in this studyÂcould, depending on its composition, be a high-risk cohort (Gleason sum of 4 + 3) that may be appropriate for androgen deprivation therapy or to be a low-risk cohort (Gleason sum of 5 and 6) for whom evidence for a benefit associated with androgen deprivation therapy is lacking.
He goes on to turn the discussion to patient pressure on their doctors. Today, he says, "patients have access to more information, and PSA levels can be monitored by physicians and patients as an indication of biochemical disease progression." "Androgen deprivation therapy," he says, "is available to silence the ticking PSA clock of disease progression in the short-to-intermediate term. Under these circumstances, the patient who focuses on achieving a lower PSA level may seek a physician who will administer androgen deprivation therapy."
"The challenge for urologists," Schellhamer concludes, "is to offer men with high-risk, potentially lethal prostate cancer androgen deprivation therapy early in their course of treatment and to avoid the unnecessary risks of androgen deprivation therapy among men with low-risk indolent disease."
But who will make this happen? Dr. Shahinian and his team would put more responsibility on the gate-keeping primary care physician. "The primary care physician should carefully consider the choice of urologist for their patients," Shahinian writes.
Dr. Schellhammer thinks this "may not be practical in the real world setting regarding decisions about androgen deprivation therapy."
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More about how this study was done
The study population as a whole was divided into two groups: patients diagnosed in the years 1997Â1999 and those diagnosed between January 1, 1992, and January 1, 1997.
The year 1997 was chosen as a threshold because in that year information from randomized control trials showed that adding androgen deprivation therapy to radiation therapy increased chance of surviving the disease compared with radiation therapy alone.
The 1997Â1999 group was further divided into a high-risk or "evidence-based" group that included patients with clinical stage T4 tumors and patients receiving radiation therapy who had either T3 or T2 tumors with a aggressive tumors, defined as Gleason score of 8Â10. Androgen deprivation therapy for these patients was considered to be evidence based, according to the results of the randomized control trials available in 1997.The other patients -- all men with lower than Gleason 8 -- were categorized in an uncertain-benefit group for androgen deprivation therapy.
Sources: JNCI news release and below.
Related Links:
Vahakn B. Shahinian , Yong-Fang Kuo , Jean L. Freeman , James S. Goodwin Affiliations of authors: Department of Internal Medicine (VBS, YFK, JLF, JSG), Department of Preventive Medicine and Community Health (YFK, JLF, JSG), Sealy Center on Aging (VBS, YFK, JLF, JSG), University of Texas Medical Branch, Galveston, TX Journal of the National Cancer Institute, Vol. 98, No. 12, 839-845, June 21, 2006
Editorial by Paul F. Schellhammer
MD, Eastern Virginia Medical School, 6333 Center Dr., Bldg. 16, Norfolk, VA 23502
This page, edited by J. Strax, last updated June 22, 2006.
Information on this website is not intended as medical advice nor to be taken as such. Consult qualified physicians specializing in the treatment of prostate cancer. Neither the editors nor the publisher accepts any responsibility for the accuracy of the information or consequences from the use or misuse of the information contained on this website.
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