A new treatment protocol that combines intensity-modulated radiation therapy (IMRT) with high-dose-rate (HDR) brachytherapy has been found to be a safe, effective method of radiation dose escalation for localized prostate cancer.
IMRT uses computer-controlled linear accelerators to modulate the intensity of an external radiation beam and deliver radiation to tumors more accurately. In HDR brachytherapy, radioactive pellets are implanted near the tumor. From 2001 through 2006, 26 consecutive men with prostate cancer (T stage ≤2b, prostate-specific antigen ≤20, and Gleason score ≤7) participated in a phase 1/phase 2 trial to examine the toxicity and efficacy of the combination of IMRT and a single-fraction HDR brachytherapy implant.
The treatment, which carried relatively low toxicity, employed a single HDR fraction of 6 Gy to the entire prostate and 9 Gy to the peripheral zone, followed by IMRT delivered in 28 fractions with a normalized total dose of 70 Gy.
The entire set of patients completed the treatment as prescribed, with no cancer recurrence and with a low rate of long-term side effects over a median follow-up period of 53 months (range, 9 to 68 months).
“Our study was designed to reduce radiation exposure to nearby healthy tissue and organs, and we were pleased to find that this unique dosing schedule is safe and effective,” noted Mitchell S. Anscher, MD, in a statement issued by Virginia Commonwealth University (VCU) in Richmond, Virginia. Anscher, the lead author of the study, is the radiation oncology chair as well as a program leader of radiation biology and oncology at the university’s Massey Cancer Center, also in Richmond. The protocol was designed by radiation oncologist Michael P. Hagan, MD, PhD, of the Massey Cancer Center. Anscher, Hagan, and colleagues reported their findings in the journal Brachytherapy (2012;11:292-298).