Patterns of failure after postoperative radiotherapy for incompletely resected (R1) non-small cell lung cancer: Implications for radiation target volume design
Menée sur 80 patients atteints d'un cancer du poumon non à petites cellules ayant subi une résection incomplète de type R1 entre 2002 et 2011, cette étude rétrospective évalue, en fonction de la présence ou non d'une extension extracapsulaire ganglionnaire et du point de vue de l'échec loco-régional et du taux de survie globale à 3 ans, l'efficacité d'une radiothérapie tridimensionnelle post-opératoire planifiée
Objective Overall survival (OS) and pattern of failure in R1-resected non-small cell lung cancer (NSCLC) patients treated with 3D-planned postoperative radiotherapy (PORT) was retrospectively evaluated. The outcomes and patterns of failure in patients with (+) and without (−) extracapsular nodal extension (ECE) were compared and analyzed with respect to the radiation target volume design. Materials and methods Eighty R1-resected (37 ECE+ and 43 ECE−) patients received PORT (60 Gy, 2 Gy daily) between 2002 and 2011. Patients with N2 disease received limited elective nodal irradiation (ENI); for pN0-1 disease the use of ENI was optional. Among ECE− (extranodal-R1) patients there were 35 pN0-1 and eight pN2 cases; in pN0-1 patients, patterns of failure and outcomes were analyzed with respect to the use of ENI. Loco-regional failure (LRF) was defined as in-field relapse; isolated nodal failure (INF) was defined as out-of-field regional nodal recurrence occurring without LRF, irrespective of distant metastases. Results The actuarial 3-year OS rate was 36.3% (median: 30 months). Three-year OS rates in the ECE− and ECE+ group were 40.4% and 31.4%, with median OS of 31 and 24 months, respectively (p = 0.43). In multivariate analysis, the presence of ECE was correlated with OS (HR = 3.02; 95% CI: 1.00–9.16; p = 0.05). Three-year cumulative incidence of LRF (CILRF) was 14.5% and 15.5% in the ECE− and ECE+ groups, respectively (p = 0.98). Three-year cumulative incidence of INF (CIINF) was 14.1% in the ECE− group and 11.1% in the ECE+ group (p = 0.76). For pN0-1 patients treated with and without ENI (13 and 22 patients) 3-year CILRF rates were 7.7% and 20.8%, respectively (p = 0.20); 3-year CIINF rates were 9.1% and 16.3%, respectively (p = 0.65). Conclusion PORT resulted in a relatively good survival of R1-resected NSCLC patients. Relatively high incidence of INF was found in both ECE+ and ECE− patients. For ECE+ patients, treated with limited ENI, distant failure remains a major concern, so the design of ENI fields seems of lesser importance. Omission of ENI in pN0-1 (extranodal-R1) patients resulted in an unacceptably high incidence of INF. We postulate the use of some form of ENI in this setting.