AUA report and update no. 8: Wednesday, April 29, 2009

Two studies presented at the AUA on Monday dealt with the mortality rates of men diagnosed with prostate cancer and treated with differing types of first line therapy.

Roehl et al. (abstract no. 817) presented information from a prospective study of the cause and timing of death in 981 men with prostate cancer diagnosed in screening studies between 1989 and 2001 who underwent different treatments. The “New” Prostate Cancer InfoLink wishes to be clear, in presenting these data, that men diagnosed in screening studies conducted between about 1989 and 2001 would have been much more likely to be diagnosed with locally advanced or advanced disease than would be the case today. With that important proviso, Roehl and her colleagues showed that the median time from diagnosis to prostate cancer-specific death was just under 6 years (71 months) and to death from other causes was about 7.6 years (91 months). They also presented interesting data on the 10-year risk of death by initial treatment type as follows:

  • Surgical treatment: risk of death from prostate cancer, 2.4 percent; risk of death from other causes, 14.2 percent
  • Radiation treatment: risk of death from prostate cancer, 4.0 percent; risk of death from other causes, 31.6 percent
  • Watchful waiting: risk of death from prostate cancer, 5.5 percent; risk of death from other causes, 52.7 percent
  • Hormone treatment: risk of death from prostate cancer, 18.5 percent; risk of death from other causes, 45.3 percent

We would point of that these data need to be interpreted with great care because we do not have available any data about the ages, stages at diagnosis, Gleason scores, etc. for these patients. It would, for example, be entirely appropriate to make the assumption that the men treated with surgery would very likely have been younger and have had less advanced disease at diagnosis than those managed with watchful waiting or hormonal therapy.

Cooperberg and colleagues (abstract no. 1276) also presented data on prostate cancer mortality related to type of treatment. However, their data is based on a retrospective as opposed to a prospective analysis. In this study, the authors analyzed risk-adjusted prostate cancer-specific mortality (PCSM) for men undergoing radical prostatectomy (RP), external-beam radiation therapy (EBRT), or primary androgen deprivation therapy (PADT), using data from the CaPSURE registry. The CaPSURE registry accrues data on men from 31 practice sites prospectively at time of diagnosis and follows them under a uniform protocol regardless of treatment until death or withdrawal from the study. Based on data from 8,321 men in the CaPSURE database, the authors identified 261 men (3.1 percent) who died of prostate cancer at a median of 6.4 years follow-up. After adjusting for age and risk, the authors compared the likelihood of PCSM after initial EBRT and PADT to the PCSM after initial RP:

  • External beam radiation therapy: hazard ratio = 2.0 (range 1.4-2.8, p < 0.001)
  • Peripheral androgen deprivation therapy: hazard ratio = 2.3 (range 1.9-2.7, p <0.001)

According to the authors, “There was no evidence that the differences among groups were affected by baseline risk” and “Absolute differences between RP and EBRT were small for men at low risk, but increased substantially for men at intermediate and high risk.” The investigators concluded that surgery for localized prostate cancer was associated with a significant and substantial reduction in PCSM relative to EBRT or PADT. Even through the patients’ baseline prostate cancer-specific risk was evaluated using the Cancer of the Prostate Risk Assessment (CAPRA) score — which is based on things like PSA level at diagnosis, Gleoason score, age, percentage of biopsy cores positive, and clinical stage at diagnosis — The “New” Prostate Cancer InfoLink has a hard time believing that we are comparing apples to apples in this study. It has long been clear that men treated with first-line surgery tend to be younger, healthier, and have earlier stage disease than men who are treated with first-line radiation therapy (let alone first-line PADT). It is also well known that African American men will tend to avoid surgery. We strongly suggest that these data are evaluated with great caution for all sorts of reasons. The “New” Prostate cancer InfoLink does, however, note that the overall mortality rate of patients in the CaPSURE database appears to be almost exactly the same as the rate in the SEER database — on which the annual projections for prostate cancer mortality are based.

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