MacRae, Robert M.

ImportanceThe optimal radiotherapy technique for unresectable locally advanced non–small cell lung cancer (NSCLC) is controversial, so evaluating long-term prospective outcomes of intensity-modulated radiotherapy (IMRT) is important.ObjectiveTo compare long-term prospective outcomes of patients receiving IMRT and 3-dimensional conformal radiotherapy (3D-CRT) with concurrent carboplatin/paclitaxel for locally advanced NSCLC.Design, Setting, and ParticipantsA secondary analysis of a prospective phase 3 randomized clinical trial NRG Oncology–RTOG 0617 assessed 483 patients receiving chemoradiotherapy (3D-CRT vs IMRT) for locally advanced NSCLC based on stratification.Main Outcomes and MeasuresLong-term outcomes were analyzed, including overall survival (OS), progression-free survival (PFS), time to local failure, development of second cancers, and severe grade 3 or higher adverse events (AEs) per Common Terminology Criteria for Adverse Events, version 3. The percentage of an organ volume (V) receiving a specified amount of radiation in units of Gy is reported as V(radiation dose).ResultsOf 483 patients (median [IQR] age, 64 [57-70] years; 194 [40.2%] female), 228 (47.2%) received IMRT, and 255 (52.8%) received 3D-CRT (median [IQR] follow-up, 5.2 [4.8-6.0] years). IMRT was associated with a 2-fold reduction in grade 3 or higher pneumonitis AEs compared with 3D-CRT (8 [3.5%] vs 21 [8.2%]; P = .03). On univariate analysis, heart V20, V40, and V60 were associated with worse OS (hazard ratios, 1.06 [95% CI, 1.04-1.09]; 1.09 [95% CI, 1.05-1.13]; 1.16 [95% CI, 1.09-1.24], respectively; all P < .001). IMRT significantly reduced heart V40 compared to 3D-CRT (16.5% vs 20.5%; P < .001). Heart V40 (<20%) had better OS than V40 (≥20%) (median [IQR], 2.5 [2.1-3.1] years vs 1.7 [1.5-2.0] years; P < .001). On multivariable analysis, heart V40 (≥20%), was associated with worse OS (hazard ratio, 1.34 [95% CI, 1.06-1.70]; P = .01), whereas lung V5 and age had no association with OS. Patients receiving IMRT and 3D-CRT had similar rates of developing secondary cancers (15 [6.6%] vs 14 [5.5%]) with long-term follow-up.Conclusions and RelevanceThese findings support the standard use of IMRT for locally advanced NSCLC. IMRT should aim to minimize lung V20 and heart V20 to V60, rather than constraining low-dose radiation bath. Lung V5 and age were not associated with survival and should not be considered a contraindication for chemoradiotherapy.Trial RegistrationClinicalTrials.gov Identifier: NCT00533949

Abstract Purpose: RTOG 0617 was a phase III randomized trial for patients with unresectable stage IIIA/IIIB non–small cell lung cancer comparing standard-dose (60 Gy) versus high-dose (74 Gy) radiotherapy and chemotherapy, plus or minus cetuximab. Although the study was negative, based on prior evidence that patients with the KRAS-variant, an inherited germline mutation, benefit from cetuximab, we evaluated KRAS-variant patients in RTOG 0617. Experimental Design: From RTOG 0617, 328 of 496 (66%) of patients were included in this analysis. For time-to-event outcomes, stratified log-rank tests and multivariable Cox regression models were used. For binary outcomes, Cochran—Mantel–Haenzel tests and multivariable logistic regression models were used. All statistical tests were two sided, and a P value <0.05 was considered significant. Results: A total of 17.1% (56/328) of patients had the KRAS-variant, and overall survival rates were similar between KRAS-variant and non-variant patients. However, there was a time-dependent effect of cetuximab seen only in KRAS-variant patients—while the hazard of death was higher in cetuximab-treated patients within year 1 [HR = 3.37, 95% confidence interval (CI): 1.13–10.10, P = 0.030], death was lower from year 1 to 4 (HR = 0.33, 95% CI: 0.11–0.97, P = 0.043). In contrast, in non-variant patients, the addition of cetuximab significantly increased local failure (HR = 1.59, 95% CI: 1.11–2.28, P = 0.012). Conclusions/Discussion: Although an overall survival advantage was not achieved in KRAS-variant patients, there is potential impact of cetuximab for this genetic subset of patients. In contrast, cetuximab seems to harm non-variant patients. These findings further support the importance of genetic patient selection in trials studying the addition of systemic agents to radiotherapy. Significance: The KRAS-variant is the first functional, inherited miRNA-disrupting variant identified in cancer. Our findings support that cetuximab has a potentially beneficial impact on KRAS-variant patients treated with radiation. The work confirms prior evidence that KRAS-variant patients are a subgroup who are especially sensitive to radiation. These findings further support the potential of this class of variants to enable true treatment personalization, considering the equally important endpoints of response and toxicity.

7501 Background: The first objective of RTOG 0617 was to compare the overall survival(OS) of patients(pts) treated with standard-dose(SD)(60Gy) versus high-dose(HD)(74Gy) radiotherapy with concurrent chemotherapy(CT). Methods: This Phase III Intergroup trial randomized 464 pts with Stage III NSCLC to the SD(60Gy) vs. HD(74Gy) arms prior to closure of the HD arm. Concurrent CT included weekly paclitaxel(45 mg/m2) and carboplatin(AUC=2). Pts randomized to cetuximab received a 400 mg/m2 loading dose on Day 1 followed by weekly doses of 250 mg/m2. All pts were to receive consolidation CT. We are reporting the final results on radiation dose. Results: 464 pts were accrued prior to closure of the HD arm in 6/11, of which 419 were eligible for analysis. Median follow up was 17.2 months. There were 2 and 10 grade 5 treatment-related adverse events(AEs) on the SD and HD arms, respectively. Grade 3+AEs were 74.2% and 78.2% on SD and HD arms, respectively (p=0.34). The median survival times and 18-month OS rates for the SD and HD arms were 28.7 vs 19.5 months, and 66.9% vs 53.9% respectively (p=0.0007). The primary cause of death was lung cancer (72.2% vs 73.5%)(p=0.84). Local failure rates at 18 months were 25.1% vs 34.3% for SD and HD patients, respectively(p=0.03). Local-regional and distant failures at 18 months were 35.3% vs 44%(p=0.04) and 42.4% vs 47.8%(p=0.16) for SD and HD arms, respectively. Factors predictive of less favorable OS on multivariate analysis were higher radiation dose, higher esophagitis/dysphagia grade, greater gross tumor volume, and heart volume >5 Gy. Conclusions: In this setting of chemoradiation for locally-advanced Stage III NSCLC, 60 Gy is superior to 74 Gy in terms of OS and local-regional control. The effect of the anti-EGFR antibody (cetuximab) awaits further follow up. This project was supported by RTOG grant U10 CA21661, CCOP grant U10 CA37422, and ATC U24 CA 81647 from the National Cancer Institute (NCI) and Eli Lilly and Company. Clinical trial information: NCT00533949.