Is a High Radiation Dose Better Than Standard Radiation Treatment in Prostate Cancer Patients?

Higher doses of radiation do not improve survival rates in patients with prostate cancer compared to standard radiation therapy, shows study. The study was conducted by a research team at Washington University School of Medicine and published in JAMA Oncology. This was the first large scale study designed to examine, if improved new therapies for prostate cancer translate into longer survival for patients. Previous studies have indicated that gradually escalating the radiation dose slows tumor growth and results in lower levels of prostate-specific antigen (PSA), an indicator of cancer growth. This study was conducted to determine if the advances in treatment improved survival rates in patients with prostate cancer.

Study Design

The study included nearly 1,500 patients with intermediate-risk prostate cancer. This category of patients had PSA scores of 10-20 ng/ml and a Gleason score of seven, which is a measure of tumor aggressiveness.

The patients were divided into two groups, the standard group received a radiation dose of 70.2 gray delivered over 39 treatment visits. The investigational group received increasing doses up to 79.2 gray delivered over 44 visits. Both treatment groups received external beam radiation.

Study findings

• Of the patients receiving standard treatment, 75% were still alive after 8 years of follow-up and among the patients who received the dose-escalation treatment, 76% were alive at the 8 year mark. The difference is not statistically significant.
• At the 8 year mark, the death rate due to prostate cancer for patients receiving standard treatment was 4% compared with 2% for patients receiving the escalating dose. The rates were also were not statistically different.
• Patients in the escalating dose group experienced more side effects such as urinary irritation or rectal bleeding, sometimes years after treatment.

"Our goal is to improve survival, but we didn't see that despite advances in modern radiotherapy," said first author Jeff M. Michalski, MD, the Carlos A. Perez Distinguished Professor of Radiation Oncology. "But we did see significantly lower rates of recurrence, tumor growth and metastatic disease - tumors that spread - in the group that received the higher radiation dose. Still, that didn't translate into better survival. The patients in the trial did better than we anticipated, and part of that may have been because of improvements in metastatic cancer therapy over the 10 years of the trial."

Looking at the side effects of higher doses of radiation, Michalski said: "If we can safely deliver the higher dose of radiation, my opinion is to do that. It does show lower risk of recurrence, which results in better quality of life. But if we can't achieve those 'safe' radiation dose goals, we shouldn't put the patient at risk of serious side effects down the line by giving the higher dose. If we can't spare the rectum or the bladder well enough, for example, we should probably back off the radiation dose. It's important to develop treatment plans for each patient on a case-by-case basis."

Reference:

1. Michalski JM, Moughan J, Purdy J, Bosch W, Bruner DW, Bahary JP, Lau H, Duclos M, Parliament M, Morton G, Hamstra D, Seider M, Lock MI, Patel M, Gay H, Vigneault E, Winter K, Sandler H. Effect of standard vs. dose-escalated radiation therapy for patients with intermediate-risk prostate cancer: The NRG Oncology RTOG 0126 randomized clinical trial. JAMA Oncology. (2018) DOI: 10.1001/jamaoncol.2018.0039

Source-Medindia