Is survival following post-operative radiotherapy in pN1-non-small cell lung cancer reduced? Results of a multivariate analysis

Prognostic factors and the role of post-operative radiotherapy (PORT) in patients with pN1 nodal stage following surgery for NSCLC were identified. The clinical course of 211 patients with pN1 nodal involvement following thoracic surgery were reviewed, 97 of them received PORT. Multi-variate survival analysis with respect to prognostic factors (including treatment) was performed. The most frequent site of recurrence was the ipsilateral bronchus-stump or hilus (63% of recurrences). The 5-year rate of intercurrent deaths for PORT was 1% vs 6% in the group without PORT. The 5-year rate of locoregional recurrence was similar (24% vs 19%) for PORT vs no PORT (p=0.97). PORT patients had a higher rate of distant metastases (p=0.04). The 5-year rate of overall survival was 45% without PORT and 25% with PORT (p=0.003). Multivariate survival analysis identified 4 prognostic factors associated with decreased survival rate: age, extended pneumectomy, number of involved nodes and PORT dose. A PORT dose of 50 Gy corresponds to an increase in relative risk of death in the range of 1.5. Patients with PORT do not have an increased rate of intercurrent deaths. However in this cohort, PORT in pN1 patients was associated with a decreased survival rate due to distant metastases. Even after correction with respect to accepted prognostic factors in multivariate survival analysis, PORT was not able to improve or equalize prognosis of these negatively selected patients. The main site of recurrence is the bronchial stump and hilus. If PORT is applied in pN1 patients, a reduction of the target volume should be discussed since local control in high-risk patients may be of relevance.