Prognostic factors for recurrence in patients with surgically resected non-small cell lung cancer

Dear Editor,

We read with interest the article by Moskalenko et al. published in the 3^rd issue 2022 of Contemporary Oncology [1] on prognostic factors for recurrence in patients with surgically resected non-small cell lung cancer. We have also been interested in postoperative survival of lung cancer patients [2, 3]. We have a few questions and would be grateful if you could answer them. As the authors showed, the TNM staging is the classification that determines the prognosis of resected patients in the first place, so it was obvious that the T factor is a risk factor for recurrence [4]. But why is smoking a risk of recurrence after resection? We would like to know the reasons. We do understand the risk of new lung cancer, but how does smoking relate to lung cancer recurrence? It would be beneficial to know how pathological findings were related to smoking and recurrence. We would like to know what kind of biological mechanism the authors assumed regarding the relationship between smoking and recurrence. Figure 1 in the article by Moskalenko et al. [1], the recurrence was up to about 42 months after surgery, and the Kaplan-Meier curve after that seemed to be plateau. Please let us know whether the timing of recurrence differed between those with T factor progress and those with smoking. The authors did not provide detailed data on smoking. It would be beneficial to know the association between recurrence and information such as smoking initiation age, smoking index, timing of smoking cessation, timing of resection, and recurrence.