This study aims to investigate the relationship between the duration of smoking cessation before surgery and postoperative complications in lung cancer patients undergoing surgery. Lung cancer surgery patients who have recently quit smoking or are long-term nonsmokers will be evaluated to determine if the timing of smoking cessation impacts the risk of complications after surgery. By analyzing these factors, the study seeks to provide guidance on optimal smoking cessation timing to reduce postoperative risks.

This prospective observational study aims to examine the impact of smoking cessation duration on postoperative complications in lung cancer surgery patients. Lung cancer remains the most lethal type of cancer globally, with non-small cell lung cancer (NSCLC) accounting for approximately 85% of cases. Tobacco use is the most well-established risk factor for lung cancer, and a significant portion of lung cancer patients have either smoked in the past or continue to smoke. Smoking status and the timing of cessation before surgery have been shown to influence postoperative outcomes. Prior research suggests that cessation at least 2-4 weeks before surgery may reduce postoperative complications, with the World Health Organization recommending a minimum of four weeks of cessation before surgery to decrease the risk of adverse outcomes.

In this study, patients will not be categorized based on smoking or cessation status alone but will be documented on a continuum by recording the exact number of days or weeks between their smoking cessation and their surgical procedure. The primary objective is to assess whether a specific duration of smoking cessation is associated with a reduced risk of postoperative complications, including both pulmonary and non-pulmonary complications. These complications are defined in two categories: respiratory (e.g., atelectasis, pneumonia, respiratory failure) and non-respiratory (e.g., atrial fibrillation, myocardial infarction, wound infection).

Patients with advanced chronic obstructive pulmonary disease (COPD), uncontrolled asthma, severe neuromuscular disease, advanced thoracic deformity, or severe cardiovascular disease will be excluded to minimize confounding variables. The study will also exclude patients with emergency surgeries, pregnant individuals, and those who have undergone prior thoracic surgeries.

The sample size calculation, performed using G*Power software, determined a minimum of 248 participants would be needed to achieve a 95% confidence level and statistical power of 95%. Data analysis will include logistic regression to examine the relationship between smoking cessation duration and the occurrence of postoperative complications. Risk assessment tools, including the ARISCAT, Gupta Postoperative Pneumonia Risk, and Melbourne Group Scale, will be utilized to evaluate each patient's risk profile.

Data collection will focus on the following variables:

Patient demographics, comorbidities, neoadjuvant therapy, preoperative smoking history, lung function tests, operative and anesthesia times, intraoperative blood loss, pathological staging, and 30-day postoperative complications.

Quality assurance will involve source data verification from medical records to ensure accuracy, as well as routine data validation checks to maintain data consistency.

The statistical analysis will be guided by a comprehensive analysis plan, detailing the primary and secondary outcome evaluations. The findings aim to contribute to understanding the optimal smoking cessation timing to reduce surgical risks and enhance patient outcomes in lung cancer surgery.

Inclusion Criteria:

• Patients aged between 18 and 80 years.
• Patients scheduled for elective surgery under general anesthesia due to NSCL.
• Patients classified as American Society of Anesthesiologists (ASA) I-III.
• Patients or their legally authorized representatives who have provided informed consent.

Exclusion Criteria:

• Patients with advanced chronic obstructive pulmonary disease (COPD) classified as GOLD Grade III-IV.
• Patients with severe and uncontrolled bronchial asthma.
• Patients with severe neuromuscular diseases or advanced thoracic deformity.
• Patients with severe heart disease classified as New York Heart Association (NYHA) Class III-IV.
• Patients with cognitive impairments.
• Patients undergoing emergency surgery.
• Pregnant patients.
• Patients with coagulopathy.
• Patients who have previously undergone video-assisted thoracoscopic surgery (VATS) and/or thoracotomy.
• Patients who died perioperatively.
• Patients or their legally authorized representatives who did not provide informed consent.

Participants will be selected from patients diagnosed with non-small cell lung cancer at the Ondokuz Mayis University Medical Faculty, Department of Thoracic Surgery. The study population consists of individuals scheduled for elective lung cancer surgery under general anesthesia, reflecting a clinical sample of patients who are typically managed within a tertiary care hospital setting.