Inclusion Criteria:

* Age ≥18 years
* Clinical stage I tumor (AJCC 8th edition) suitable for segmentectomy, according to the treating thoracic surgeon

o Note: Patients must undergo segmentectomy for a peripheral lesion ≤2 cm to be included in the primary analysis. Individual ligation of the segmental artery(s) and segmental bronchus is the minimum definition for a segmentectomy. Division of the segmental vein and intraoperative frozen section to assess surgical margins and N1 lymph nodes are strongly encouraged, but the absence of either is not a criterion for exclusion.

* Pathology of NSCLC o Tissue diagnosis of NSCLC is not required before enrollment. A pathologic diagnosis of NSCLC may be confirmed preoperatively with biopsy, intraoperatively with frozen section, or postoperatively on final pathology.

Other considerations:

* Patients with ground-glass opacities will have their tumor size recorded on the basis of the size of the solid component.
* Any non-lung cancer treated in the past with no obvious recurrence or ongoing treatment is not a criterion for exclusion.
* The registry study will be monitored by Thoracic Surgery team at MSK.
* This study will be in collaboration with the Thoracic Surgical Oncology Group (TSOG) of the American Association for Thoracic Surgery.

Exclusion Criteria:

* Actively receiving lung cancer treatment or a history of lung cancer in the previous 5 years
* History of chemotherapy or radiation therapy for a previous lung cancer
* Synchronous secondary cancer in the lung or elsewhere in the body at the time of surgery
* Carcinoid tumors
* History of other malignancies within the past 3 years, with the exception of non-melanoma skin cancer, superficial bladder cancer, and carcinoma in situ of the cervix
* Actively receiving treatment for other malignancies

* Cases of lobectomy in conjunction with segmentectomy from another lobe and ≥2 segmentectomies from different lobes either en bloc or separate will be excluded from the primary analysis.

* Multi-segmental resection from the same lobe is not a criterion for exclusion.

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 05/15/2025. Questions regarding updates should be directed to the study team contact.