Page 13 - Read Online

Page 6 of 9 Cosgun et al. Mini-invasive Surg 2019;3:32 I http://dx.doi.org/10.20517/2574-1225.2019.024

Histopathologic tumor types and their effect on lymph node positivity also were analyzed retrospectively.
Of the patients, 134 could be categorized according to predominance of acinar, solid, lepidic, and
micropapillary patterns. Micropapillary histologic subtype was associated with lymph node positivity.
Other subtypes did not show significance (P = 0.65, P = 0.22, P = 0.78, P = 0.005, respectively).

DISCUSSION
Lymphatic dissemination is the major route of systematic metastasis, and it is the major determinant of
long-term patient outcome. When a patient with clinical stage N0 disease has been demonstrated to have
N1 or N2 positivity, not only prognosis, but also treatment modalities change. Larger consolidation size,
central tumor location, and clinical N1-N2 stage have been defined as predictors of mediastinal lymph
[11]
node metastasis . A recent study demonstrated a significant increase in nodal upstaging to be related with
[12]
the duration between radionuclear evaluation and surgery .

A current study shows that < 2 cm tumors may show occult nodal metastasis, so that dissection of lymph
[13]
nodes during sublobar resection increases survival for patients underwent sublobar resection . The same
study claimed that nonanatomic resections without hilar lymphadenectomy may miss this upstaging.
Preoperative radiographic tumor size, tumors not in the upper lobe, high carcinoembryonic antigen levels,
and micropapillary predominant adenocarcinomas were identified as predictors for unexpected N1 or
[14]
N2 node positivity in adenocarcinoma patients . When two major types (squamous cell carcinoma and
adenocarcinoma) were compared, lymph node metastasis occurred more frequently in adenocarcinomas
than in squamous cell carcinomas and it was reported to be uncommon for mediastinal lymph node
metastasis in tumors with a diameter < 3 cm. Poor differentiation grade may have an important role in
[15]
lymph node metastasis . Despite these findings, several investigators claim that mediastinal lymph node
[7]
dissection may be unnecessary for adenocarcinomas ≥ 1 cm . In our study, patients with clinicaly N0
disease, had postoperatively N stages (N1, N2) as high as 7.4% and 12.3% of cases, respectively, among
all those with stages T1a and Tab cancer. Stage T1c group demonstrated similar upstaging (3.5% patient
was N1 disease and 17.8% patient was N2 disease postoperatively). Our results contradicted the literature
findings and recommendations. We recommended mediastinal and hilar systematic lymph node dissection
to be performed for all stages, including stage 1A.

In another trial on adenocarcinomas ≤ 30 mm, solid pattern, maximum standardized uptake value, and
lymphovascular invasion were independent predictors for lymph node metastasis .
[16]
Adenocarcinoma is a heterogeneous type of lung carcinoma and mostly consists of mixed subtypes.
According to one study on solitary peripheral subsolid nodules; speculation, lesion size, vascular
convergence and solid proportion are predictive parameters of invasive adenocarcinoma . In another
[17]
study that used nomogram for predicting risk of invasive pulmonary adenocarcinoma for pure ground-
glass opacity nodules; lesion size, speculation, lobulation, air bronchogram, vascular convergence, pleural
[18]
tag were risk factors for being invasive pulmonary adenocarcinoma .
Adenocarcinoma in situ and minimally-invasive adenocarcinoma, in which a lepidic pattern is a major
component, may show very good prognosis without mediastinal and hilar lymph node metastasis .
[19]
Lepidic predominant, minimally-invasive adenocarcinoma, and adenocarcinoma in situ also are specified
as safe tumors for lymph node invasion [20,21] . Since a lepidic pattern is known to be noninvasive and often
appears as a ground glass opacity (GGO) on radiologic evaluation, and a patient with a GGO nodule on
tomography is likely to be diagnosed with adenocarcinoma in situ or minimally-invasive adenocarcinoma
[19]
pathologically, systematic lymph node dissection might not be considered . Lepidic predominance has
been shown to be the safest subtype in regard to mediastinal and hilar lymph nodes in our study (P = 0.78),
similar to findings in the literature.