SAN FRANCISCOPatients with inoperable, locally advanced lung cancer can tolerate up to 80 Gy of conformally delivered radiation therapy, given in 1.6 cGy fractions twice daily, following carboplatin(Drug information on carboplatin) (Paraplatin)/paclitaxel (Taxol) or carboplatin/vinorelbine (Navelbine), according to a phase I study presented at the 43rd Annual Meeting of the American Society for Therapeutic Radiology and Oncology (abstract 35).
In this dose-escalation trial, 36% of patients had a complete or partial response after receiving both chemotherapy and radiotherapy.
"We wanted to find the maximally tolerated radiation therapy dose," said Julian Rosenman, MD, professor of radiation oncology, University of North Carolina (UNC) at Chapel Hill. The patients in the trial, however, did not undergo concurrent therapy, because the study was designed before this treatment method was proved effective. "We thought that if we could give very high doses of radiation, perhaps concurrent therapy wasn’t necessary," Dr. Rosenman said.
The study was performed by researchers at UNC, Duke University, Wake Forest University, and the Medical University of South Carolina. Between November 1997 and March 2001, 39 patients with a median age of 59 were enrolled; 61% were male and 39% were female. The size of their tumors ranged from 1 to 11 cm. Patients had stage IIB lung cancer (3%), stage IIIA (64%), or stage IIIB (33%).
Patients were enrolled in cohorts of seven, with the first seven receiving carboplatin/paclitaxel and the second seven carboplatin/vinorelbine. The two arms were evaluated separately in order to assess the impact of the induction regimen on the rate of grade 3 toxicity and, thus, the maximum tolerated dose.
Thirty-seven patients completed their chemotherapy regimen. After chemotherapy, 17 had a partial response, 12 had no response, 6 progressed, and 2 could not be evaluated.
Both groups of patients received radiation doses starting at 73.6 Gy, and escalating in 6.4 Gy intervals to 80 and 86.4 Gy. An earlier trial had successfully tested doses up to 74 Gy in patients who received chemotherapy, Dr. Rosenman said.