Prostatectomía y Radioterapia, debate sobre el "timing"

Medscape Medical News > Oncology
Radiation After Prostatectomy: Debate Over Timing
Alexander M. Castellino, PhD
March 31, 2015



Among men with newly diagnosed prostate cancer who are offered radical prostatectomy (RP) with curative intent, around 60% of patients have high-risk features, which are associated with cancer recurrence. In these patients, radiation therapy (RT) after surgery is expected to improve cure rates.

In clinical practice, there is uncertainty about the timing of radiation. Should it be given soon after RP (adjuvant RT), or only after biochemical recurrence, when levels of the prostate-specific antigen (PSA) rise?

Two new studies could add to the debate on whether RT should be provided after surgery or after biochemical recurrence as salvage RT, but overall, both studies provide confidence to those who offer adjuvant RT.

The two longitudinal studies are based on analyses from Italian and Surveillance, Epidemiology, and End Results (SEER)–Medicare databases of cohorts of men who received RP and included men who received postsurgical radiation.
"The timing of radiation does not determine the risk for complication," radiation oncologist Timothy N. Showalter, MD, MPH, from the University of Virginia School of Medicine in Charlottesville, the corresponding author on both reports, told Medscape Medical News.
"In these large cohorts of patients, these studies importantly demonstrate that waiting for a period of time after prostatectomy to initiate radiation does not confer any additional benefit of fewer side effects, compared with giving it sooner," Michael J. Zelefsky, MD, professor of radiation oncology and vice-chair of clinical research in the Department of Radiation Oncology at the Memorial Sloan Kettering Cancer Center in New York City, told Medscape Medical News. He was not involved in either study, and was approached for comment.

The Italian study, published in the March 15 issue of the International Journal of Radiation Oncology, Biology, Physics, showed that the timing of radiation is not significant for any of the adverse-event outcomes associated with radiation — both gastrointestinal and genitourinary.

However, the analysis of the men in the SEER–Medicare linked database, published online February 23 in PLOS ONE, indicated that adjuvant RT is associated with lower rates of gastrointestinal events than salvage RT, with no increase in genitourinary events.In both studies, erectile dysfunction rates were similar for adjuvant RT and salvage RT, and were similar to rates in patients undergoing only RP.
"These are both well-conducted studies," another expert approached for comment, Anthony V. D'Amico, MD, PhD, professor in the Department of Radiation Oncology and chief of genitourinary radiation oncology at the Dana-Farber Cancer Center and the Brigham and Women's Hospital in Boston, told Medscape Medical News.

The seemingly different conclusions from both studies arise from the fact that they were nonrandomized studies, so all patient confounders could not be adjusted for; each study can only generate a hypothesis that needs to be prospectively assessed in a randomized trial, Dr D'Amico explained.
Two such trials — RADICALS and RAVES — are ongoing, he noted.