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Howard Sandler, MD, MS, reviews evidence on hormonal and radiation therapies during his IPCC presentation.
Analysis by risk group, however, showed that most of the benefit was reaped by those with an intermediate risk, with participants in that arm experiencing a 61% OS with combination therapy versus 54% with RT alone.
By contrast, the study found that low-risk and high-risk patients experienced OS gains that were not statistically significant. For the lowrisk group, the OS advantage was 67% with the combination therapy versus 64% for RT alone; for the high-risk group, it was 53% for the combination versus 51% for RT alone. Findings of other clinical trials support longer-term use of ADT in high-risk patients, the authors noted.
“What this trial did was firmly establish the role of short-term hormone therapy in combination with radiation for intermediate-risk prostate cancer patients,” Sandler said. “Intermediate-risk patients who may have received radiation therapy alone now are being encouraged to pursue combination therapy with androgen ablation because of the results of this randomized trial.”
Sandler said the results build upon several studies that have shown a clinical advantage to using a short-term combination of ADT with RT in intermediate- and high-risk patients. The results of the TROG 96.01 trial, published in Lancet Oncology last year, showed that six months of neoadjuvant ADT with RT reduced PSA progression (HR = 0.57; confidence interval [CI], 0.46-0.72; P < .0001) and local progression (HR = 0.45; CI, 0.30-0.66; P = .0001), and improved event-free survival compared with RT alone (HR = 0.51; CI, 0.42-0.61; P < .0001).2
While short-term ADT appeared to benefit intermediate-risk patients, higher-risk patients appear to benefit from longer-term hormonal therapy. For example, in the RTOG 85-31 study, the absolute survival rate after a median follow-up of 10 years was significantly higher in patients receiving adjuvant hormonal therapy plus RT (49%) compared with patients who received RT alone (39%).3 A secondary analysis showed that patients who received hormone therapy for at least five years benefited more than patients who received it for less than five years.4
Other studies have supported the use of continuous ADT in high-risk patients. In a National Cancer Institute of Canada study, high-risk patients treated with continuous ADT plus RT showed an overall survival advantage of 74% compared with 66% in patients being treated with ADT alone after seven years of follow-up.5
Despite these studies supporting the use of combination therapy in high-risk patients, Sandler cited a study that showed that more than 40% of these patients received hormone therapy alone as a primary treatment.6
“Many men with high-risk prostate cancer, even today, are being treated with hormone therapy alone, and thus probably being undertreated for their locally advanced disease,” Sandler said. “Given that we know that adding radiation therapy…can benefit men with high-risk localized prostate cancer, I strongly believe that primary hormonal therapy should rarely be used as long as men have a life expectancy otherwise of more than five years.”
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