The IASLC Lung Cancer Staging Project: Analysis of Resection Margin Status and Proposals for Residual Tumor (R) Descriptors for Non-Small Cell Lung Cancer.

INTRODUCTION: To validate the prognostic relevance in NSCLC of potential residual tumor (R) descriptors, including the proposed International Association for the Study of Lung Cancer definition for uncertain resection -R(un).

METHODS: 14,712 patients undergoing resection with full R status and survival were analyzed. The following were also evaluated: <3 N2 stations explored; lobe-specific nodal dissection (LSND); extra-capsular extension (ECE); highest lymph node station status; carcinoma in situ at bronchial resection margin (BRMcis); pleural lavage cytology (PLC). Revised categories of R0, R(un), R1 and R2 were tested for survival impact.

RESULTS: 14,293 cases were R0, 263 R1 and 156 R2 (median survival: not reached, 33, 29 months, respectively). R status correlated with T and N categories. 9,290 (63%) cases had ≥3 N2 stations explored and 6,641 (45%) had LSND, correlated with increasing pN2. ECE was present in 62 (17%) of 364 cases with available data. The highest station was positive in 942 (6.4%). PLC was positive in 59 (3.5%) of 1,705 cases: 13 had BRMcis. After reassignment, due to inadequate nodal staging in 56%, 6,070 cases were R0, 8,185 R(un), 301 R1 and 156 R2. In node positive cases, median survival was 70, 50, 30 months for R0, R(un), (p<0.0001) and R1 (p<0.001), respectively, with no significant difference between R0 and R(un) in pN0 cases.

CONCLUSIONS: R descriptors have prognostic relevance with R(un) survival stratifying between R0 and R1. Therefore, a detailed evaluation of R factor is of particular importance in the design and analyses of clinical trials of adjuvant therapies.