Higher doses of radiation don’t improve survival in prostate cancer, study

Side effects also a concern.


Gathering data by comparing the standard radiation treatment, a new study by the Washington University School of Medicine in St. Louis suggests that higher doses of radiation do not improve survival for many patients with prostate cancer.

The study is the first that is large enough to examine whether these improved measurements translate into longer survival for patients. Scientists involved 1,500 patients with the middle of the road chance prostate growth, the hazard class in which most patients fall. To be characterized in this hazard classification, patients, by and large, have PSA scores of 10-20 ng/ml and a Gleason score of seven, the last of which is a measure of tumor forcefulness. Both treatment bunches got outside pillar radiation.

The standard gathering got a radiation dosage of 70.2 dark conveyed more than 39 treatment visits. The investigational amass got expanding dosages up to 79.2 dim conveyed more than 44 visits.

Of the 748 men accepting standard treatment, 75 percent were as yet alive following eight years of development. Of the 751 men accepting the measurements acceleration treatment, 76 percent were alive at the eight-year point — a distinction that isn’t measurably critical.

These general survival rates incorporate passings for any reason, not only those because of prostate growth. Through the span of the investigation, 51 patients passed on of prostate growth, which is 3.4 percent of all patients selected.

At the eight-year point, the passing rate because of prostate disease for patients accepting standard treatment was 4 percent contrasted and 2 percent for patients getting the heightening measurements. These rates additionally were not measurably extraordinary.

First author Jeff M. Michalski, MD, said, “Our goal is to improve survival, but we didn’t see that despite advances in modern radiotherapy. 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.”

“While there was no difference in overall survival numbers, some differences in side effects and in whether further treatment was needed later. Such differences could help doctors and patients in deciding the best treatment course.”

Patients in the standard dose group were more likely to undergo further therapies to control tumors that had grown larger or that had spread to another site in the body. But patients in the escalating dose group experienced more side effects — such as urinary irritation or rectal bleeding — sometimes years after treatment.

During the 10 years it took to enroll enough patients in the trial, Michalski said, at least six new therapies were approved for recurrent or metastatic prostate cancer, and these therapies have been shown to improve survival. It is possible the patients in the standard treatment arm — who were shown to need more follow-up therapies — would not have done as well as the group receiving the escalating dose had these new therapies not become available.

“If there is a difference between standard and escalating doses, it’s hard to show it when the patients who later develop recurrent cancer can have their lives extended through the use of additional therapies,” said Michalski, who treats patients at Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital. “Of course, these additional therapies have their own side effects, as does the higher initial dose of radiation therapy. In addition, the selective use of androgen withdrawal therapy has been shown to improve survival in men treated with radiation therapy. This treatment can be combined with either standard or higher dose radiation therapy.”

“If we can safely deliver the higher dose of radiation, my opinion is to do that,” Michalski added.

“It does show a 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.”

The new study, published March 15 in JAMA Oncology.