Prostate-Only vs Whole-Pelvis Radiotherapy in Gleason Grade 5 Prostate Cancer
In a retrospective analysis published in European Urology, Sandler et al examined the protocol for treating aggressive prostate cancer. Researchers aimed to study the impact of whole-pelvis radiation on men with Gleason grade 5 disease who had been treated with external-beam radiotherapy with or without a brachytherapy boost.
With aggressive forms of prostate cancer, it is often unclear whether radiation therapy should be applied to the prostate alone or to the whole pelvis. The reason a low dose of radiation may be applied to the whole pelvis is that pelvic lymph nodes may have microscopic cancer cells within them. Previous tests have proven that a high dose of radiation is effective in treating prostate cancer.
Study Background
“We undertook this study because several randomized trials have failed to show any benefit to prophylactically treating the whole pelvis region with radiation, along with treating the prostate,” said study author Amar Kishan, MD, Assistant Professor in the Department of Radiation Oncology at the David Geffen School of Medicine at the University of California, Los Angeles. “However, these trials have been limited by delivering substandard doses of radiation to the prostate. This raises the question of whether treating the pelvic nodes in conjunction with high-dose radiation to the prostate would be helpful.”
The study assessed 1,170 patients who were treated at 12 sites between 2000 and 2013 for biopsy-proven Gleason grade 5 prostate cancer. Using a statistical model, the researchers compared the outcomes for men who were treated with radiation for their prostate alone vs men who received similar high-dose treatment for their prostate in conjunction with radiation for their whole pelvis.
Findings
In the study, 41% of patients treated with external-beam radiotherapy and 73% of patients treated with external-beam radiotherapy plus a brachytherapy boost received whole-pelvis radiotherapy. The adjusted 5-year biochemical recurrence–free survival rates with whole-pelvis radiotherapy in the external-beam radiotherapy and external-beam radiotherapy–plus–brachytherapy groups were 66% and 88%, respectively. Without whole-pelvis radiotherapy, the 5-year rates for the external-beam radiotherapy and external-beam radiotherapy–plus–brachytherapy groups were 58% and 78%, respectively.
Whole-pelvis radiotherapy was associated with improved biochemical recurrence–free survival among patients treated with external-beam radiotherapy plus brachytherapy, but no evidence for improvement was found in those treated with only external-beam radiotherapy. Whole-pelvis radiotherapy was not significantly associated with improved distant metastasis–free or prostate cancer–specific survival in the external-beam radiotherapy group or in the external-beam radiotherapy–plus–brachytherapy group.
The researchers concluded, “Whole-pelvis radiotherapy was not associated with improved prostate cancer–specific survival or distant metastasis–free survival in patients with Gleason grade 5 prostate cancer who received either external-beam radiotherapy or external-beam radiotherapy plus brachytherapy. However, whole-pelvis radiotherapy was associated with a significant improvement in biochemical recurrence–free survival among patients receiving external-beam radiotherapy plus brachytherapy. Strategies to optimize whole-pelvis radiotherapy, potentially with the use of advanced imaging techniques to identify occult nodal disease, are warranted.” They also noted that a randomized trial is required to further prove their conclusions.
Disclosure: For full disclosures of the study authors, visit europeanurology.com.
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