Conformal Radiotherapy Shows Promise in Early-Stage Lung Cancer

Zosia Chustecka

July 24, 2007

July 24, 2007 — For patients with stage 1 non–small-cell lung cancer (NSCLC) who are unable to tolerate surgery, accelerated conformal radiotherapy offers a new option, and results from the first prospective trial of this approach suggest that outcomes are similar to those seen with alternative therapies such as limited resection and stereotactic body radiotherapy (SBRT). "Our trial showed a median survival of 35 months at the most recent analysis, which compares well with survival of around 32 months that has been reported in these other studies," lead investigator Jeffrey Bogart, MD, from State University of New York Upstate Medical University, told Medscape.

Dr. Bogart reported results from the 5-year trial at the recent American Society for Clinical Oncology 43rd Annual Meeting, in Chicago, Illinois. The study was conducted at 10 institutions across the United States and was funded through the Cancer and Leukemia Group B (CALGB), which is sponsored by the National Cancer Institute.

"Although the majority of patients with stage 1 NSCLC may be cured following surgery to remove a whole section of the lung, a substantial proportion of these patients have poor lung function or other medical problems, making them unsuitable for major surgery," Dr. Bogart explained. In the past, these patients were treated with limited surgical resection, where only the tumor itself and a small portion of the diseased lung are removed, but in recent years new approaches to radiotherapy have been explored.

The approach investigated in the trial headed by Dr. Bogart relies on advanced technology such as computed tomography (CT) or magnetic resonance imaging (MRI) to locate the tumor and surrounding normal structures and then involves "sculpting" the dose of accelerated 3-dimensional conformal radiotherapy so that it fits precisely. "We are better able to conform the radiation dose to the exact location of the tumor, avoiding critical structures and providing more intense therapy directly to the tumor," Dr. Bogart commented in a press statement. This reduces the radiation exposure to the surrounding normal tissue and reduces the patient's risk for radiation toxicity, he added.

The trial enrolled a total of 40 patients, but 1 patient denied protocol treatment, leaving 39 who were eligible. The team used a constant 70-Gy total radiotherapy dose but reduced the number of daily fractions that were delivered, from 28 treatments in 5.5 weeks to 17 treatments in 3.5 weeks.

The major response rate was 74% (31% complete response, 43% partial response), and 26% had stable disease. After a median follow-up of 38.1 months, 21 patients remained alive, which is a "very promising result in this population," Dr. Bogart commented. Only 3 patients had a recurrence of the tumor in the same location in the lung, and only 1 patient experienced a severe adverse effect of the radiation therapy, such as difficulty breathing, he added.

"Our outcomes demonstrate that accelerated 3-dimensional conformal radiotherapy is feasible in high-risk early-stage NSCLC, and therapy can safety be completed in less than half the time of traditional regimens," Dr. Bogart commented. The outcomes are comparable to what has been seen in previous trials of limited resection and SBRT, he added. There is a suggestion that conformal radiotherapy may be better tolerated than SBRT — in a recently reported trial involving 70 patients, 6 died shortly after the procedure, he commented. In addition, SBRT did not appear to be very effective against centrally located tumors, although it may be a good option for peripherally located tumors.

However, which approach to radiotherapy is best in these stage 1 NSCLC patients and even whether it should be chosen instead of limited resection all remain "unanswered questions," Dr. Bogart commented. These approaches need to be compared head-to-head in clinical trials, butat the same time, new techniques are being developed to increase the accuracy and precision of the radiotherapy being delivered, he said. For example, his team is evaluating respiration gating and also image-guided radiation techniques, both of which take into account how the tumor moves when the person breathes.

American Society for Clinical Oncology 43rd Annual Meeting: Abstract 7556. Presented June 5, 2007.

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