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Cosgun et al. Mini-invasive Surg 2019;3:32 I http://dx.doi.org/10.20517/2574-1225.2019.024 Page 3 of 9

preoperatively were excluded. Forty-one patients who underwent mediastinoscopy or EBUS preoperatively
and patients who were reported as negative were included in this study. A total number of 158 patients
without PET/CT, Mediastinoscopy, EBUS- evident stage N1 or N2 disease and those who underwent
anatomic lung resections with systemic mediastinal and hilar complete lymph node dissections were
analyzed. Mediastinal lymph node dissections yielded 1242 (mean, 18.8 ± 10.6) lymph nodes with complete
dissection of stations 5, 6, 7, 8, 9, 10, 11, 12 on the left, and 1919 lymph nodes (mean 20.9 ± 11.8) with
complete dissection of stations 2R, 4R, 7, 8, 9, 10, 11 on the right hemithorax.

Surgical technique
Patients were intubated and single-lung ventilation was placed via fiberoptic bronchoscopy. A lateral
decubitus position was used. A two-port technique was used for videoassited thoracoscopic surgery (VATS)
lobectomy. For RATS, three ports were opened, keeping 10 cm between each port and 10-15 cm from the
target. We preferred to use the VATS-based approach for our RATS technique. When a fourth arm was
used, it was placed lateral to the posterior arm. The technique we described here was used for Da Vinci
[9]
SI systems (Da Vinci System Intuitive Surgical, Sunnyvale, CA, USA) . The Da Vinci robotic system was
used in 83 patients, while 75 underwent biportal VATS. Postoperative nodal status and number of positive
lymph nodes were evaluated in each group and compared with each other.

Segmentectomy was preferred for tumors smaller than 2 cm and negative lymph nodes or for larger
tumors in patients with poor pulmonary function who could not tolerate lobectomy, especially those who
do not have visceral pleural invasion in our center. But if the tumor invaded visceral pleura or especially
hilar lypmh node positivity could change the surgeon’s decision. Also if the remaining tissue after
segmentectomy seems not have a good ventilation or blood supply, we decided to perform completion
lobectomy during the operation.

Lymph node dissection
Mediastinal and N1-level lymph node dissections were performed in similar manners on all patients
regardless of whether they underwent RATS or VATS. Typically dissected mediastinal lymph node
stations were 2R, 4R, and 7-9 for patients with right-sided tumors, and 5-9 en bloc with perinodal fatty
tissue for those with left-sided tumors. Segmentectomy became an operation option for peripheral,
clinical T1N0M0, and 2 cm or smaller in size tumors. N1-level lymph nodes, and stations 10 and 11 for
lobectomies, and additionally, station 12 were dissected completely and separately during segmentectomies.
For segmentectomy, stations 11 and 12 nodes were dissected completely and evaluated by frozen section
[10]
analysis . If either of them was positive, we preferred to perform lobectomy instead of segmentectomy.

Lymph node status and number of positive lymph nodes were evaluated for each patient. Rate of positive
lymph nodes was calculated as the ratio of positive lymph nodes to the number of dissected lymph nodes.

Histopathology
Tumors were classified histologically as well (grade 1), medium (grade 2), and poorly (grade 3)
differentiated. Histopathologic types of tumors also were analyzed. In 134 patients, the tumor could be
categorized according to predominance of acinar, solid, lepidic, and micropapillary patterns.

Lymphovascular and visceral pleural invasion of tumors was analyzed according to positive lymph nodes
and possible effects on N upstaging.

Statistical analysis
Lymph node positivity and nodal status were evaluated in each subgroup, comparing stages T1 vs. T2, T1
vs. T3, and T2 vs. T3. T stage subgroups, such as T1a, Tb, T1c, T2a, T2b, and T3, also were compared using