The report was an update on the LungART international clinical trial, which, at the 2020 ESMO meeting, was shown not to improve disease-free survival over the course of 3 years. The update showed that, in addition to the lack of disease-free survival benefit, there was also no difference in metastases, and patients randomized to PORT had higher rates of death and grade 3/4 cardiopulmonary toxicity. The investigators returned this year to expand on another finding from the trial, a 51% reduction in the risk of mediastinal relapse with postoperative radiotherapy. The new analysis suggests there might still be a role for PORT in select patients, perhaps those with heavy nodal involvement, said lead investigator and presenter Cecile Le Pechoux, MD, radiation oncologist at the Gustave Roussy cancer treatment center in Villejuif, France.
For now, “personalized prescription of PORT should be based on prognostic factors of relapse and joint assessment of toxicity and efficacy,” she said.
Study discussant Pilar Garrido, MD, PhD, head of thoracic tumors Ramon y Cajal University Hospital, Madrid, agreed that there might still be a benefit for people with multiple N2 nodal station involvement, but at present, she said, “for me PORT cannot be the standard of care ... given the toxicity and mortality among PORT patients in LungART.”
The trial randomized 501 patients with non–small cell lung cancer with mediastinal involvement to either PORT at 54 Gy over 5.5 weeks or no further treatment following complete resection. Neoadjuvant or adjuvant chemotherapy were allowed.
The 3-year mediastinal relapse-free survival was 72.26% in the control arm but 86.06% with PORT (hazard ratio, 0.45; 95% confidence interval, 0.3-0.69).
“There is a significant difference” when it comes to mediastinal relapse, and “patients who have PORT do better. If we look at the location of mediastinal relapse, most [patients] relapse within the initially involved node. This is important information,” Dr. Le Pechoux said.
For left-sided tumors, the most frequent sites of mediastinal relapse were thoracic lymph node stations 7, 4L, and 4R. For right sided tumors, the most frequent stations were 4R, 2R and 7.
Prognostic factors for disease-free survival included quality of resection, extent of mediastinal involvement, and lymph node ratio (involved/explored). Nodal involvement was a significant prognostic factor for overall survival, but PORT was not (HR, 0.98; 95% CI, 0.7-1.4).
Mediastinal involvement with more than two node stations and less than an RO, or microscopically margin-negative resection, increased the risk of relapse.
The work was funded by the French National Cancer Institute, French Health Ministry, Institute Gustave Roussy, and Cancer Research UK. Dr. Pechoux and Dr. Garido disclosed ties to AstraZeneca, Roche, Amgen, and other companies.
This article was updated 9/24/21.