Expert Point of View: Jason A. Efstathiou, MD, DPhil

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Although these two trials reported at the ASTRO Annual Meeting are seemingly different, they both establish the value of radiation-based therapy in prostate cancer, demonstrating overall survival benefit and favorable toxicity profiles in high-risk, locally advanced, and castrate-resistant metastatic disease, stated formal discussant Jason A. Efstathiou, MD, DPhil, Massachusetts General Hospital, Boston.

According to some practice pattern databases, only 14% of patients with high-risk prostate cancer currently receive external-beam radiotherapy, whereas up to 46% may receive primary androgen-deprivation monotherapy, he noted. “These patients are undertreated and underserved,” he stated.

The final results of the Intergroup trial show that the answer to the question of whether radiation added to androgen-deprivation therapy improves survival in high-risk/locally advanced patients “is a resounding yes,” Dr. Efstathiou told listeners. He added that the number needed to treat to save 1 life over 10 years is 17 patients (and to save 1 life from prostate cancer death is 9), and the treatment is very well tolerated. He noted that these results are consistent with another similarly designed large Scandinavian randomized trial, SPCG-7.

‘Gold Standard’

“[External-beam radiotherapy and androgen-deprivation therapy] should now be the gold standard against which interventions for high-risk and locally advanced prostate cancer are compared, including radical prostatectomy. The role of pelvic irradiation, extent of androgen suppression, and the addition of more aggressive systemic therapy to radiation and androgen-deprivation therapy awaits results of ongoing trials,” he said.

In the metastatic setting, radium-223 prolonged overall survival and time to first skeletal-related event, with favorable safety. “If approved, radium-223 will be a first-in-class addition to a growing arsenal of new drugs exploiting novel therapeutic targets in castration-resistant prostate cancer and may lead to broad use of a radiopharmaceutical as a new standard,” he told the audience. Use of radium-223 in earlier disease settings, such as asymptomatic metastatic disease and in the prechemotherapy space, as well as in combination with other therapies, requires further study, he said.

“Taken together, these abstracts show that the use of radiation-based therapy endures, providing perhaps a gold standard and a new standard…. It improves overall survival in high-risk locally advanced and metastatic castrate-resistant prostate cancer. These two abstracts proudly proclaim that radiation is no quackery and no humbug,” he stated. ■

Disclosure: Dr. Efstathiou reported no potential conflicts of interest.

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