2006 Prostate Cancer Symposium - Session On The Treatment Of Low And Intermediate Risk Prostate Cancer
Dr. Laurie Klotz discussed the approach of WW with delayed intervention. He cited the 20-40 year natural history of CaP and approximately 10 year lead time bias. For patients with low risk CaP, WW with delayed intervention is a sound approach according to Dr. Klotz's data. At a median follow-up of 72 months in 299 patients on WW, 34% came off WW while 65% remain on surveillance. At 9 years, overall survival was 85% CaP specific survival was 99%. High risk patients will be detected by following the PSA doubling time and thus intervention can be implemented. These data are the basis for the START study (Surveillance Treatment Against Restricted Treatment), which have 2,100 patients randomized to either WW or choice of standard therapy.
DR. Huland from Hamburg argued that surgery is the best treatment for low and intermediate risk CaP. In 4,762 patients treated by RP in Hamburg, a shift in low risk disease from 24.5% to 60% occurred from 1992 to 2005. In their series, both low stage and low grade tumors are cured by RP in greater than 80%. This is supported by numerous studies he cited from the literature. In modern series, the morbidity of RP is very low. With regard to potency, a soon to be published series from his institution including 524 men, found 96% were potent at 12 months if younger than 55 years, 70% of these without PDE-5 inhibitors. In men greater than 65 years, 80% and 55% were potent in total and without PDE-5 inhibitors, respectively.
Dr. Potters from the New York Prostate Institute argued for brachytherapy as the best treatment for low and intermediated risk CaP. Implant quality is paramount to outcomes, said Dr. Potters and the biologically effective dose calculation as describe at Mt. Sinai is essential to standardize outcomes. The addition of EBRT to brachytherapy alone significantly decreases the potency rate at 5 years from 90% to 65%. Using new intraoperative dynamic dosing calculations, the toxicity of brachytherapy is decreased, to include irritative symptoms and incidence of acute urinary retention.
Dr. Kuban from M.D. Anderson Cancer Center argued for external beam radiation as the best treatment for low and intermediated risk CaP. IMRT typically provides 8 beam angles with intensity modulators to give a conformal dose distribution to the prostate, which decreases rapidly to the bladder and rectum. A dose-volume histogram is set up for individual patients to maximize prostate dosing and minimize toxicity. To compensate for prostate movement during treatment, ultrasound or CT scanning on each treatment day can realign the patient for optimal treatment. The disease free outcome for low risk men at 10 years is 80-90%. It is about 10% less for intermediate risk, although the addition of androgen deprivation improves the cancer specific outcomes. Hypofractionated RT will likely become used more in the future. Hypofractionation gives larger, but less frequent dosing fractions and may improve outcomes and decrease total dosing necessary.
Dr. Hamdy, from the University of Sheffield, UK provided an update on the ProtecT trial. This trial is in its second phase to test the effectiveness of RP, ERBT and WW in men with localized CaP. A biorepository is central to the study. 6,000 men were invited to enroll at several UK centers. Patients were randomized to an active 2-treatment arm of ERBT vs. RP or a 3-arm trial that also included WW. As an alternative, patients could elect a preferred treatment. However, with training to eliminate recruitment bias, the trial is very successful in accruing patients to a randomized approach (now 70%) and will continue accrual to 2008.
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By Christopher P. Evans, MD
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2006 cancer de prostatã Simpozion - Sesiunea privind tratamentul scãzut de risc ºi a celor intermediare în cancerul de prostatã - 2006 Prostate Cancer Symposium - Session On The Treatment Of Low And Intermediate Risk Prostate Cancer - articole medicale engleza - startsanatate