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Conventionally Fractionated vs Moderate Hypofractionated Radiation Therapy for Localized Prostate Cancer: Long-Term Update


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As reported in the Journal of Clinical Oncology by Avkshtol et al, the 10-year update of a single-center trial has confirmed the primary analysis of the study, showing no superiority in 5-year biochemical and/or clinical disease failure rate with moderate hypofractionated intensity-modulated radiation therapy (H-IMRT) vs conventionally fractionated IMRT (C-IMRT) in patients with localized prostate cancer.

Study Details

In the trial, 303 men with protocol-defined intermediate- and high-risk prostate adenocarcinoma were randomly assigned to receive C-IMRT at 76 Gy in 38 fractions (n = 152) or H-IMRT at 70.2 Gy in 26 fractions (n = 151). Patients with high-risk disease were prescribed 24 months of androgen-deprivation therapy (ADT) and underwent lymph node irradiation; those with intermediate-risk disease were prescribed 4 months of ADT at physician’s discretion. The primary endpoint was cumulative incidence of biochemical and/or clinical disease failure.

KEY POINTS

  • The 10-year cumulative incidence of biochemical or clinical disease failure was 25.9% in the C-IMRT group vs 30.6% in the H-IMRT group.
  • No significant differences between groups were observed for biochemical failure, local recurrence, all-cause mortality, or prostate cancer–specific mortality.

Long-Term Outcomes

The median follow-up for the current analysis was 122.9 months. On the basis of updated National Comprehensive Cancer Network risk classification, 28 patients (9.2%) had low-risk, 189 had (62.4%) intermediate-risk, and 86 had (28.4%) high-risk disease. There was no significant difference in either short-term or long-term median ADT use between groups.

The 10-year cumulative incidence of biochemical and/or clinical disease failure was 25.9% in the C-IMRT group vs 30.6% in the H-IMRT group (hazard ratio = 1.31, 95% confidence interval [CI] =0.82–2.11). The 10-year cumulative incidence of distant metastasis was higher in the H-IMRT group (14.3% vs 6.4%, difference = 7.8%, 95% CI = 0.7%–15.1%). No significant differences between the C-IMRT group vs the H-IMRT group were observed in 10-year cumulative incidence of biochemical failure (21.1% vs 25.4%, P = .26), local recurrence (4.7% vs 4.0%, P = .82), all-cause mortality (24.4% vs 33.2%, P = .12), or prostate cancer–specific mortality (4.4% vs 4.4%, P = .89). Cause of death was not known for 31.9% of patients who died.

The investigators concluded, “H-IMRT failed to demonstrate superiority compared with C-IMRT in long-term disease outcomes.”

Eric M. Horwitz, MD, of the Department of Radiation Oncology, Fox Chase Cancer Center, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by the National Cancer Institute and by a grant from Varian Medical Systems. For full disclosures of the study authors, visit ascopubs.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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