Less lung toxicity in lung cancer patients with radiation therapy

18 Oct 2015

Patients with stage III non-small cell lung cancer (NSCLC) who receive intensity modulated radiation therapy (IMRT) have 44% fewer cases of severe pneumonitis. They also have improved likelihood of completing consolidative chemotherapy after radiation, compared to patients who receive three-dimensional conformal radiation therapy (3-D CRT).

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.

Secondary analysis of a large phase 3 study

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 3, randomized clinical trial of patients with locally-advanced non-small cell lung cancer (NSCLC) conducted from 2007 to 2011.

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 radiation therapy, 47% were treated with IMRT and 53% 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% of the IMRT group had stage IIIB tumors, compared to 30.3% of the 3-D CRT group.


Positive patient outcomes reported

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.
  • 3.5% of IMRT patients had severe pneumonitis compared to 7.9% of the 3-D CRT patients.
  • IMRT also significantly reduced radiation doses 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.

“The findings may fundamentally change the way we deliver radiation therapy”

“We looked at one of the largest clinical trials ever done for NSCLC and found that the most important predictors of severe pneumonitis were IMRT technique and the lung V20. The low dose bath created by IMRT such as the lung V5 was not associated with any survival or toxicity outcome. These findings may fundamentally change the way we deliver radiation therapy for locally-advanced lung cancer,” said Stephen Chun, MD, lead author of the study and Fellow in the department of radiation oncology at The University of Texas MD Anderson Cancer Center in Houston.

“By reducing severe and life threatening pneumonitis, IMRT can improve patients’ quality of life, reduce hospital/intensive care unit admissions and decrease supplemental oxygen use. In our study, it seemed that IMRT might also facilitate patients being able to tolerate higher doses of consolidative chemotherapy which are standard after radiation.”

Source: eCancer News
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