Ms. Merel Nissenberg is the President of the National Alliance of State Prostate Cancer Coalitions, a nation-wide organization comprised of state prostate cancer coalitions dedicated to saving men’s lives and enhancing the quality of life of prostate cancer patients and their families through awareness, education, and the development of a public policy network.
She offers two views of hypofractionated radiotherapy for prostate cancer.
NASPCC supports the use of new treatments and therapies that good evidence shows help prostate cancer patients, but only those that do not have more risks than benefits as compared to conventional care. Consider radiation therapy in prostate cancer. As radiation therapists and medical oncologists consider future trends in radiation therapy for prostate cancer, there are two settings in which the idea of hypofractionated radiotherapy is being explored. It may not yet be ready for prime time.
The first setting is either the postoperative adjuvant period for prostate cancer patients with aggressive pathological features following radical prostatectomy or as salvage therapy for patients with biochemical recurrence after prostatectomy. Although there is now evidence from Phase III trials supporting the use of hypofractionation in terms of good biochemical control and favorable short-term toxicity, the role of such radiotherapy in these patients is still considered investigational due to conflicting results with long-term genitourinary late toxicity.
The second setting involves men with localized prostate cancer who are often treated with external beam radiation therapy (EBRT) as their primary treatment, with treatments given over the course of 8-9 weeks. For these types of localized prostate cancer patients, trials are now being conducted to ascertain the noninferiority of hypofractionation.
That is, can larger doses of radiation per treatment over a shorter time be just as effective as standard EBRT and with no increased toxicity?
In one such trial reported in Journal of Clinical Oncology in 2017 (V35, no. 17, 1884-1890), intermediate risk patients were randomized to either conventional radiotherapy of 78 Gy in 39 fractions over 8 weeks (598 patients) or to hypofractionated radiotherapy of 60 Gy in 20 fractions over 4 weeks (608 patients). No androgen deprivation was allowed during the trial.
The primary outcome was “biochemical-clinical failure” (BCF), defined as the first occurrence of any one of 4 outcomes: PSA failure, hormonal intervention, clinical evidence of local or distant failure, or death as a result of prostate cancer. Median follow-up was 6 years.
The five-year BCF disease-free survival was 85% in both arms of the trial, and there were no significant differences between the two arms in terms of grade 3 or worse late GU and GI toxicity. There were twelve deaths as a result of prostate cancer in the standard RT arm, and ten deaths as a result of prostate cancer in the hypofractionated arm.
The trial investigators concluded there is evidence to support the use of moderate hypofractionated RT in patients with intermediate-risk prostate cancer but not in high-risk disease.
For hypofractionated radiotherapy to be adopted as standard practice for patients with intermediate-risk disease, it must be shown to be equivalent or superior to conventional radiotherapy in terms of excessive toxicity, especially late radiation genitourinary and gastrointestinal toxicity. More studies are therefore needed, particularly because there has been conflicting evidence in terms of such toxicity.
While some reports from last year conclude that moderate hypofractionation is safe and effective for localized prostate cancer and further suggest it should be standard of care, it cannot be over-emphasized that caution is strongly urged.
Longer-term toxicities are not yet known from the increased dosage of radiation with the new modalities. NASPCC strongly supports more clinical trials and longer-term follow-up to answer the question of long-term toxicity with the use of hypofractionation.