Long-term ADT, high-dose radiation improved outcomes in high-risk prostate cancer

A treatment regimen that consisted of androgen deprivation therapy for 2 or more years plus radiation doses of at least 75.6 Gy significantly improved outcomes in men with high-risk prostate cancer, according to results of a retrospective analysis.

Nguyen and colleagues compared outcomes after high-dose (≥75.6 Gy) and low-dose (<75.6 Gy) external beam radiation, with or without androgen deprivation therapy (ADT) in 741 men with high-risk prostate cancer.

Men were treated with external beam radiotherapy at a single tertiary institution between 1987 and 2004. Median follow-up was 8.3 years.

Actuarial 5-year OS rates were 92% among men treated with high-dose radiation plus ADT, 87% for men treated with low-dose radiation plus ADT, and 81% for men who received low-dose radiation alone.

Actuarial 10-year OS rates were 72% among men treated with high-dose radiation plus ADT, 67% among men treated with low-dose radiation plus ADT, and 56% among men who received low-dose radiation alone.

Quynh-Nhu Nguyen

“We demonstrated that, with modern techniques and high-dose radiation therapy in combination with androgen deprivation therapy, these patients have improved biochemical, clinical and survival outcomes,” Quynh-Nhu Nguyen, MD, of the department of radiation oncology at The University of Texas MD Anderson Cancer Center, told HemOnc Today. “Specifically, few men die of their prostate cancer and even fewer have symptomatic local failures affecting their quality of life when treated with definitive radiation therapy and androgen deprivation therapy.”

The biochemical failure-free survival rate in men treated with both ADT and high-dose radiation was 82% at 5-years and 77% at 10 years (P<.0001).

Further, researchers observed higher clinical local failure rates at 5 years among men who received low-dose radiation and no ADT compared with men who received high-dose radiation plus ADT (24.2% vs. 0%, P<.0001).

The symptomatic local failure rate at 10 years was 3%. The figure included patients treated with previous radiation regimens.

“Patients should be thoroughly counseled on the appropriate treatment options, cancer outcomes and potential toxicity,” she said. “At our institution, patients are seen in a multidisciplinary clinic and counseled by urologists, radiation and medical oncologists. While this is not a randomized trial, randomized data comparing different modalities treated with modern techniques are not available. Therefore, large institutional reports with long-term follow-up can provide valuable guidelines for clinicians and decision-making information for patients.”

Because the treatment groups were not randomized, “any comparison of outcomes across groups suffers from biases such as treatment selection and differences in treatment era,” Sean P. Elliott, MD, MS, of the department of urology at the University of Minnesota, wrote in an accompanying editorial.

“The authors report rates of symptomatic local failure but do not report rates of adverse effects,” Elliott wrote. “They only report symptoms affecting quality of life among the subset of patients with a confirmed local recurrence. It is essential that we approach the measurement of adverse effects of cancer therapy with the same vigor with which we measure cancer cure rates. We should not, as the authors do here, declare one treatment regimen superior to another without proper attention to adverse effects. Each patient’s tolerance threshold for cancer recurrence and adverse effects will dictate an individualized approach to cancer management. The patient deserves to have the information needed to make an informed decision.”

Nguyen said this is an attractive modality for patients who wish to avoid surgery or who are not good surgical candidates. The toxicities associated with this regimen — including quality-of-life endpoints — have been well published, she added.

For more information:

Elliott SP. Cancer. 2013;doi:10.1002/cncr.28208.
Nguyen QN. Cancer. 2013;doi:10.1002/cncr.28213.

Quynh-Nhu Nguyen, MD, can be reached at The University of Texas MD Anderson Cancer Center, 1840 Old Spanish Trail, Unit 1150, Houston, Texas 77054; email: qnnguyen@mdanderson.org.

Disclosure: The researchers report no relevant financial disclosures.