The concept of residual tumor classification proposed by the Union for International Cancer Control (UICC) was used to assess the completeness of surgical resection, and non-small cell lung cancer (NSCLC) patients with incomplete resection were more likely to occur recurrence, leading to significantly poor survival. But this R classification only refers to the surgical margin and neglects other factors associated with surgical quality, such as the extent of lymph node dissection (LND). Therefore, the International Association for the Study of Lung Cancer (IASLC) proposed the definition of uncertain resection [R(un)], which includes the suboptimal extent of LND. However, the clinical significance of R(un) is still controversial. On the one hand, some researches demonstrated that R(un) had definite prognostic significance, with R(un) survival stratifying between R0 and R1. On the other hand, some studies indicated that in early-stage NSCLC, the suboptimal extent of LND had no impact on survival, and the concept of R(un) might be insignificant in these patients. Even in those studies supporting the prognostic significance of R(un), which kind of patients is suitable for R(un) was still unclear. Thus, the investigators explore the impact of the R(un) on the long-term survival of patients with NSCLC using a large cohort in China, to identify those patients who could really benefit from the LND required by the R0 classification proposed by IASLC.

Inclusion Criteria:

1. Primary non-small cell lung cancer
2. With pulmonary resection

Exclusion Criteria:

1. Sublobar resection
2. R1/R2
3. Positive highest mediastinal lymph nodes
4. Operative death

The data of included patients is extracted from the Hospital Information System of Sun Yat-sen University Cancer Center from 2001 to 2024.