SAN FRANCISCO—Radiotherapy dose escalation is critical to improving survival in some patients with prostate cancer, according to a study presented at the 43rd Annual Meeting of the American Society for Therapeutic Radiology and Oncology (abstract 247). In the study, patients were followed for 8 to 12 years after treatment.
"By cranking up the dose 5% to 6%, we can increase survival by 50% in some patients," said lead researcher Gerard E. Hanks, MD, retired chairman of the radiation oncology department at Fox Chase Cancer Center.
In the study, which took place between 1989 and 1992, more than 200 patients with varying PSA levels—most greater than 10 ng/mL—received escalating doses of radiation therapy ranging from 68 Gy to 79 Gy.
The study is one of the first to examine long-term response to radiation therapy. "We’re always talking about not having long-term data in radiation oncology," Dr. Hanks said. "This study gives us one of the first measures of long-term survival. It affords an opportunity to better understand dose response, side effects, and the long-term effects of dose escalation, such as reducing metastasis rates."
Of the 232 patients, three were not available for follow-up. Sixty-nine patients are living cancer-free, 54 living patients have had PSA failure, and 8 patients have had metastasis. Seventeen patients have died of prostate cancer, and 81 have died of other causes.
To analyze the effect of radiation dose on survival, the researchers divided the patients into three groups according to initial PSA level—PSA under10 ng/mL, PSA 10 to 19.9 ng/mL, and PSA over 20 ng/mL.
The patients in each category were then divided into a favorable and unfavorable group, based on prognostic indicators at the beginning of treatment. Those in the unfavorable groups had bifocal disease and a Gleason sum of 7 or higher.
