SAN FRANCISCORadiotherapy 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 levelsmost greater than 10 ng/mLreceived 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 levelPSA 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.