In a French phase II study (RTEP7–IFCT-1402) reported in The Lancet Oncology, Vera et al found that adaptive radiotherapy based on fluorine F-18–labeled fluorodeoxyglucose (FDG)–positron-emission tomography (PET) residual uptake appeared to improve local disease control compared with standard radiotherapy in patients with inoperable stage III non–small cell lung cancer (NSCLC).
Study Details
In the multicenter noncomparative trial, 158 patients without an EGFR mutation or ALK rearrangement were randomly assigned between November 2015 and July 2021 to receive boosted radiotherapy (n = 81) or standard radiotherapy (n = 77). All patients received two cycles of induction platinum-based chemotherapy and then chemoradiotherapy with platinum-based chemotherapy and radiotherapy at 42 Gy for three cycles over 8 weeks. In the boosted radiotherapy group, patients with FDG-PET residual uptake after 42 Gy received boost radiotherapy up to 74 Gy in 33 fractions, with all other patients in the group and all patients in the standard radiotherapy group receiving 66 Gy in 33 fractions over 6.5 weeks.
The primary outcome measure of the trial was the 15-month local control rate among eligible patients who received at least one dose of concomitant chemoradiotherapy.
Key Findings
In the boosted radiotherapy group, 80 patients (99%) received induction chemotherapy and 68 (84%) received chemoradiotherapy; of these 68, 48 (71%) received a radiotherapy boost. In the standard radiotherapy group, 77 patients (100%) received induction chemotherapy and 73 (95%) received chemoradiotherapy. A total of 140 eligible patients, including 67 in radiotherapy boost group and 73 in the standard radiotherapy group, were included in the analysis.
At final analysis, median follow-up among the 140 eligible patients was 45.1 months (95% confidence interval [CI] = 39.3–48.3 months). The 15-month local control rate was 77.6% (95% CI = 67.6%–87.6%) in the boosted radiotherapy group and 71.2% (95% CI = 60.8%–81.6%) in the standard radiotherapy group.
Median progression-free survival was 22.3 months (95% CI = 14.8–33.7 months) in the boosted radiotherapy group and 12.3 months (95% CI = 9.4–23.3 months) in the standard radiotherapy group.
Grade 3 or 4 adverse events within 90 days from the start of chemoradiotherapy were observed in 20 (29%) of 68 patients in the boosted radiotherapy group and 33 (45%) of 73 in the standard radiotherapy group, including serious adverse events in 7% vs 14%. The most common grade 3 or 4 adverse events were febrile neutropenia (10% vs 22%) and anemia (7% vs 12%). The sole treatment-related death was due to septic shock in a patient in the standard radiotherapy group.
The investigators concluded, “A thoracic radiotherapy boost, based on interim [FDG-PET], led to a meaningful local control rate with no difference in adverse events between the two groups in organs at risk, in contrast with previous attempts at thoracic radiation intensification, warranting a randomized phase III evaluation of such [FDG-PET]-guided radiotherapy dose adaptation in patients with stage III NSCLC.”
Pierre Vera, MD, of the Nuclear Medicine Department and QuantIF LITIS (EA4108), Centre Henri Becquerel, Rouen, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by the Programme Hospitalier de Recherche Clinique National 2014. For full disclosures of the study authors, visit thelancet.com.
