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Page 2 of 9 Cosgun et al. Mini-invasive Surg 2019;3:32 I http://dx.doi.org/10.20517/2574-1225.2019.024

Conclusion: We were unable to demonstrate a relationship between T stage and N status. Factors contributing to
unexpected N positivity were tumor characteristics that could not be identified in the preoperative period. We
recommend performing systematic mediastinal lymph node dissection regardless of the size and histopathologic
type of adenocarcinoma. In our study, robotic surgery and lobectomy operation showed superiority in dissecting
more lymph nodes.

Keywords: Adenocarcinoma, robot-assisted thoracoscopic surgery, lymphovascular invasion, micropapillary
predominance

INTRODUCTION
Lung cancer is one of the leading causes of death worldwide. Anatomic lung resections with systematic
lymph node dissection have become the recommended treatment for early stage nonsmall lung cancer
[1]
(NSCLC) . Many investigators and clinicians recommend systematic nodal dissection to all lung cancer
[2]
patients except those with clinical stage I disease .
The Guidelines of the European Society for Medical Oncology (2014) recommend that preoperative
invasive mediastinal staging (fine-needle aspiration with endobronchial ultrasonography/endoscopic
ultrasonography guidance, or mediastinoscopy) should be used only if positive hilar nodes (stage N1 or
N2) are suspected or tumor is located centrally on chest computed tomography (CT) or positron emission
[3]
tomography (PET)/CT scan . However, clinically diagnosed cN0 disease preoperatively may sometimes
[4]
be upstaged to N1 (pN1) or N2 (pN2) postoperatively . Debate continues over whether systematic lymph
node dissection is necessary for all patients with T1 or T2 tumors without signs of metastatic disease
on preoperative clinical staging studies, such as CT-PET/CT, endobronchial ultrasound (EBUS), and
[7]
[5,6]
endoscopic ultrasonography (EUS) . Watanabe et al. advocated that mediastinal nodal dissection would
be unnecessary in patients with peripheral small lung cancers (≤ 1 cm for adenocarcinomas and 2 cm for
tumors other than adenocarcinoma). We speculated that adenocarcinoma subtypes are heterogeneous
[8]
groups of lung cancers, and may even consist of mixed subtypes with different metastatic characteristics .
We also speculated that upstaging may be related to surgical technique and may change in the hands of the
same surgeons with different surgical techniques.

Many studies have shown that the incidence of nodal upstaging postoperatively is a quality measure of
[4]
surgery . However, we speculated that upstaging may also be related to other characteristics of tumor in
adenocarcinoma.

In this study, we tried to identify the relationships between tumor size, sub-histology, prognostic factors,
and postoperative nodal upstaging in patients with clinical stage N0 adenocarcinoma who underwent
minimally-invasive surgery.

METHODS
Of 274 patients who underwent minimally-invasive anatomic lung resections for primary lung cancer
between January 2012 and December 2017, 158 (102 male, 56 female; mean age, 62.3 ± 8.4 years; range,
42-92 years) had clinical stage N0 primary lung adenocarcinoma and underwent minimally-invasive
anatomic lung resections and systematic mediastinal lymph node dissections robotic assisted surgery
(RATS; n = 83) and video thoracoscopic surgery (n = 75). We retrospectively analyzed their prospectively
collected medical records. A total of 17 patients were excluded because of insufficient data. Patients with
positive mediastinal lymph nodes on mediastinoscopy and EBUS were underwent neoadjuvant treatment
and excluded from the study. Patients who were diagnosed to have positive mediastinal lymph nodes