Austin (United States) For patients with locally advanced and unresectable non-small cell lung cancer (NSCLC), standard use of more precise intensity-modulated radiation therapy (IMRT) is recommended instead of alternative 3D conformal radiation therapy (3D- CRT). ).
This conclusion is based on the findings of a recent study by researchers at the University of Texas MD Anderson Cancer Center.
The research, just published in JAMA Oncology, showed that IMRT had comparable survival rates and had fewer adverse effects.
A prospective secondary analysis of the long-term outcomes of 483 patients in the randomized phase III NRG Oncology-RTOG 0617 trial showed that those treated with 3D-CRT were significantly more likely to experience severe pneumonitis (inflammation of the lungs) than patients treated with IMRT. with rates of 8.2 percent and 3.5 percent, respectively.
According to senior author Stephen Chun, M.D., associate professor of Radiation Oncology, this study should provide finality to what has been a long-standing debate about the optimal radiation technique for locally advanced NSCLC.
"3D-CRT is a rudimentary technique that has been around for more than 50 years. Our findings show that it is time to routinely adopt IMRT instead of 3D-CRT for lung cancer, just as we did for lung tumors. prostate, anus and brain decades ago," Chun said. . "IMRT's improved accuracy translates into real benefits for patients with locally advanced lung cancer."
3D-CRT aims and shapes radiation in straight lines aimed at tumors, but lacks the ability to curve and bend into complex shapes, resulting in unnecessary radiation exposure to nearby organs. IMRT, developed in the 1990s, uses advanced computational methods to dynamically modulate numerous beams of radiation to sculpt radiation into the shape of tumors. While this can deliver radiation more precisely and protect normal tissue, bringing in radiation from multiple directions can also create a large area exposed to low doses of radiation below 5 Gray (Gy), known as a low-dose radiation bath.
The unknown long-term effects of this low-dose bath on the lungs have fueled a historic debate about IMRT and 3D-CRT in lung cancer, despite significant evidence of the other benefits of IMRT. In this study, the researchers showed that low-dose radiation bath was not associated with excess secondary cancers, long-term toxicity, or survival with long-term follow-up.
Patients had numerically better but statistically similar five-year overall survival rates for IMRT (30.8 percent) compared to 3D-CRT (26.6 percent), as well as progression-free survival rates (16.5 percent). percent versus 14.6 percent). Taken together, these results favored IMRT, even though patients in the IMRT group had significantly larger tumors and more tumors in unfavorable locations near the heart.
These findings also highlight the importance of using IMRT to minimize cardiac exposure at doses of 20 to 60 Gy. Historical concern has focused primarily on pulmonary exposure, but this study demonstrated that the amount of heart exposed to 40 Gy independently predicted survival in a multivariable analysis. Specifically, patients with less than 20 percent of the heart exposed to 40 Gy had a significantly better median survival of 2.4 years compared with 1.7 years for patients with more than 20 percent of the heart exposed to 40 Gy. .
According to Chun, these data validate efforts to limit the volume of the heart that receives 40 Gy, aiming for less than 20% as a new radiation planning goal.
"As a substantial number of patients achieve long-term survival from locally advanced lung cancer, cardiac exposure can no longer be an afterthought," Chun said. "It is time for us to focus on maximizing radiation precision and compliance to reduce cardiopulmonary exposure and put aside historical concerns about low-dose bathing."
This conclusion is based on the findings of a recent study by researchers at the University of Texas MD Anderson Cancer Center.
The research, just published in JAMA Oncology, showed that IMRT had comparable survival rates and had fewer adverse effects.
A prospective secondary analysis of the long-term outcomes of 483 patients in the randomized phase III NRG Oncology-RTOG 0617 trial showed that those treated with 3D-CRT were significantly more likely to experience severe pneumonitis (inflammation of the lungs) than patients treated with IMRT. with rates of 8.2 percent and 3.5 percent, respectively.
According to senior author Stephen Chun, M.D., associate professor of Radiation Oncology, this study should provide finality to what has been a long-standing debate about the optimal radiation technique for locally advanced NSCLC.
"3D-CRT is a rudimentary technique that has been around for more than 50 years. Our findings show that it is time to routinely adopt IMRT instead of 3D-CRT for lung cancer, just as we did for lung tumors. prostate, anus and brain decades ago," Chun said. . "IMRT's improved accuracy translates into real benefits for patients with locally advanced lung cancer."
3D-CRT aims and shapes radiation in straight lines aimed at tumors, but lacks the ability to curve and bend into complex shapes, resulting in unnecessary radiation exposure to nearby organs. IMRT, developed in the 1990s, uses advanced computational methods to dynamically modulate numerous beams of radiation to sculpt radiation into the shape of tumors. While this can deliver radiation more precisely and protect normal tissue, bringing in radiation from multiple directions can also create a large area exposed to low doses of radiation below 5 Gray (Gy), known as a low-dose radiation bath.
The unknown long-term effects of this low-dose bath on the lungs have fueled a historic debate about IMRT and 3D-CRT in lung cancer, despite significant evidence of the other benefits of IMRT. In this study, the researchers showed that low-dose radiation bath was not associated with excess secondary cancers, long-term toxicity, or survival with long-term follow-up.
Patients had numerically better but statistically similar five-year overall survival rates for IMRT (30.8 percent) compared to 3D-CRT (26.6 percent), as well as progression-free survival rates (16.5 percent). percent versus 14.6 percent). Taken together, these results favored IMRT, even though patients in the IMRT group had significantly larger tumors and more tumors in unfavorable locations near the heart.
These findings also highlight the importance of using IMRT to minimize cardiac exposure at doses of 20 to 60 Gy. Historical concern has focused primarily on pulmonary exposure, but this study demonstrated that the amount of heart exposed to 40 Gy independently predicted survival in a multivariable analysis. Specifically, patients with less than 20 percent of the heart exposed to 40 Gy had a significantly better median survival of 2.4 years compared with 1.7 years for patients with more than 20 percent of the heart exposed to 40 Gy. .
According to Chun, these data validate efforts to limit the volume of the heart that receives 40 Gy, aiming for less than 20% as a new radiation planning goal.
"As a substantial number of patients achieve long-term survival from locally advanced lung cancer, cardiac exposure can no longer be an afterthought," Chun said. "It is time for us to focus on maximizing radiation precision and compliance to reduce cardiopulmonary exposure and put aside historical concerns about low-dose bathing."