San Antonio, October 18, 2015 — Patients with stage III non-small cell lung cancer (NSCLC) who receive intensity modulated radiation therapy (IMRT) have 44 percent fewer cases of severe pneumonitis and improved likelihood of completing consolidative chemotherapy after radiation, compared to patients who receive three-dimensional conformal radiation therapy (3-D CRT), according to research presented today at the American Society for Radiation Oncology's (ASTRO's) 57th Annual Meeting.

The standard of care for patients with locally-advanced (stage III) lung cancer is concurrent chemotherapy with radiation therapy (RT). Two different types of RT are typically used to treat these patients: 3-D CRT and IMRT. Although IMRT is a more advanced and more expensive form of RT, it can target treatment to lung tumors while minimizing radiation exposure of sensitive organs like the lungs and heart from high radiation doses.

This study is a secondary analysis of the data compiled from NRG/RTOG 0617 to compare the use of IMRT and 3-D CRT in patients with lung cancer. NRG/RTOG 0617 was a large, multi-institutional phase III, randomized clinical trial of patients with locally-advanced non-small cell lung cancer (NSCLC) conducted from 2007 to 2011. The original study compared a high-dose of 74 Gy to a standard dose of 60 Gy. All patients received concurrent chemotherapy consisting of carboplatin/paclitaxel and were randomized to be treated with or without cetuximab.
Of the 482 patients treated with RT, 47 percent were treated with IMRT and 53 percent were treated with 3-D CRT. Because the original trial design was not randomized for radiation technique, the IMRT group had larger and more advanced-stage tumors. Data indicated that 38.6 percent of the IMRT group had stage IIIB tumors, compared to 30.3 percent of the 3-D CRT group.

The study results showed that although the IMRT patients had more advanced tumors, they had a lower occurrence of severe pneumonitis (for this study, this was defined as lung inflammation that required oxygen, steroids, or mechanical ventilation; and/or led to death) than patients who had been treated with 3-D CRT. Data indicated that 3.5 percent of IMRT patients had severe pneumonitis compared to 7.9 percent of the 3-D CRT patients (P = 0.046). IMRT remained associated with less severe pneumonitis in multivariate analysis (HR 0.44, P=0.0653), and was particularly pronounced in large tumors that were bigger than the median size of 460 mL (HR 0.22, P = 0.02). IMRT was also associated with significantly lower doses of radiation delivered to the heart which were highly associated with patient survival. Additionally, patients treated with IMRT were more likely to complete high-dose consolidative chemotherapy than patients treated with 3-D CRT (37 percent versus 29 percent, P = 0.051).

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