15-Y Data in Early Prostate Cancer: Radiation Bests Watching

Same "Ballpark" as Surgery

Nick Mulcahy

October 05, 2011

October 5, 2011 (Miami Beach, Florida) — After 15 years, men with early prostate cancer who were treated with external-beam radiotherapy were better off than men who were followed with watchful waiting, according to Scandinavian investigators.

Radiotherapy significantly reduced distant progression and improved progression-free survival.

However, radiotherapy has not yet provided a significant survival benefit in the randomized trial of 214 men from Sweden, Denmark, and Norway.

The survival figures are trending in favor of radiotherapy, said lead study author Anders Widmark, MD, professor of radiation oncology at Umeå University in Sweden. He was reporting the new data here at the American Society for Radiation Oncology 53rd Annual Meeting.

At 15 years, the men treated with radiotherapy (n = 107) had an overall survival rate of 40%; men treated with watchful waiting (n = 107) had a rate of 39% (P for difference = .77). The cancer-specific survival rate was better with radiotherapy than with watchful waiting (76% vs 71%; P for difference = .51).

Early prostate cancer was defined in the trial as T1b–T2, pN0, grade 1/2, M0. Most of the men (around 67%) in both groups were T2, Dr. Widmark noted. Median age in the radiotherapy group was 69.4 years; in the watchful waiting group, it was 67.7 years.

The overall and cancer-specific survival benefit seen with radiotherapy at 15 years is comparable to that seen with prostatectomy in another study of men with early disease from Sweden.

"The results are in the same ballpark as the surgical study," Dr. Widmark told Medscape Medical News, referring to Scandinavian Prostate Cancer Group Study Number 4 (SPCG-4).

Dr. Widmark pointed out that, despite the benefit seen with treatment in these studies, "we still can't tell which individual patient will benefit."

That is the Nobel Prize question.

He continued: "The big issue is to find the guys who really need treatment. That is the Nobel Prize question."

"It's a fantastic study," said Alan Pollack, MD, chair of radiation oncology at the University of Miami Miller School of Medicine in Florida. "But it's not powered for survival because they didn't reach their accrual," he told Medscape Medical News.

"They are still valuable data. We need comparative data on the efficacy of interventions in early prostate cancer," Dr. Pollack continued.

Watchful Waiting Was Standard in Mid-1980s

The majority of the patient cohort is from North Sweden (n = 166), and a minority is from Denmark and Norway. When the trial started in the mid-1980s, watchful waiting was the standard of care, Dr. Widmark explained. The use of surgery and radiotherapy was just beginning to increase, he said.

Radiotherapy was given with 4-field-box external-beam radiotherapy (64 Gy/32 fractions with a 2 cm margin) from 1986 to 1993, and then changed to 4-field conformal radiotherapy (64 to 68 Gy with a 1.5 cm margin). The investigators eventually moved to 78 Gy, Dr. Widmark said.

Patients received clinical evaluations every 6 months for the first 2 years, and annually thereafter. The clinical exams included ultrasound, rectal palpation, and blood tests, and eventually included the prostate-specific antigen test.

Patients only received "further investigations" if symptomatic. This protocol is different from modern active surveillance studies, in which patients who are being watched undergo regular biopsies.

Hormonal treatment was given in both groups on objective progression. Some patients in the watchful waiting group received external-beam radiotherapy, said Dr. Widmark. The primary end point was progression-free and overall survival.

At 15 years, radiotherapy had a significantly better rate of progression-free survival (both biochemical and local progression) than watchful waiting (65% vs 36%; P for difference < .0001). Radiotherapy also significantly reduced distant progression (81% vs 65%; P for difference < .022).

The authors have disclosed no relevant financial relationships.

American Society for Radiation Oncology (ASTRO) 53rd Annual Meeting: Abstract LB2. Presented October 3, 2011.

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