Page 50 - Read Online

Page 4 of 11 Kato et al. Mini-invasive Surg 2021;5:5 I http://dx.doi.org/10.20517/2574-1225.2020.98

of securing better surgical margins by segmentectomy combined with adjacent subsegmentectomy if
segmentectomy alone cannot secure sufficient surgical margins.

Perelman first described the traditional precision excision method; it is somewhat similar to wedge
resection but involves the non-use of some staplers and the use of electrocautery to secure a sufficient
[26]
surgical margin . This method has the following advantages: (1) maximum conservation of lung tissue
in limited resection for deep-seated lesions; (2) minimal deformity or damage to the adjacent lung tissue;
[27]
and (3) ability to obtain the maximum margin of tissue around lesions . A large wedge resection using
a stapler might cause a large deformation; in such cases, this method can be advantageous. In particular,
when the tumor is superficial on a flat surface, such as interlobar in hilum site or at the bottom of the lower
lobe, this method might be useful, as wedge resection using a stapler might be impossible to perform due
to a thick parenchyma.

While segmentectomy and subsegmentectomy are anatomical resections, wedge resection and precision
excision are non-anatomical resections. There are some advantages and disadvantages to anatomical
resections because it is necessary to dissect the hilar area. While lymph node metastasis can be evaluated
via lymph node dissection, severe adhesion of the hilum can occur after surgery. Therefore, in cases
where cancer recurs and a second surgery is needed after the first surgery, it is assumed that performing a
second surgery is difficult due to severe adhesions. On the other hand, although non-anatomical resections
have an advantage in that adhesion of the hilum is less likely to occur, it is challenging to evaluate lymph
node metastasis. Therefore, non-anatomical resections might be appropriate for cases that do not require
evaluation of lymph node metastasis. Thus, there are conflicting differences between anatomical and non-
anatomical resections. Careful selection of these procedures must be performed by considering the future
clinical course of each patient.

Generally, the decision between anatomical resection as segmentectomy and non-anatomical resection
[28]
as wedge resection depends on the tumor location in small-sized lung cancer. For example, Doo et al.
reported that wedge resection would be difficult for tumors located > 20 mm from the pleural surface.
[29]
Suzuki et al. suggested that the probability of nodule detection failure is high for tumors located > 5
mm from the pleural surface and for tumors < 10 mm in diameter. In sublobar resection techniques, it is
[30]
important to secure sufficient surgical margins from targeted tumors . The surgical margins are assumed
to be more limited in wedge resection than in segmentectomy because wedge resection for tumors deeply
located from the pleural surface makes it difficult to secure an adequate surgical margin. Mohiuddin et al. [31]
reported that the margin distance in wedge resection for small non-small cell carcinoma affects local
recurrence and that increasing the margin distance significantly decreases the local recurrence risk. The
selection of these procedures should be considered to secure sufficient surgical margins based on tumor
characteristics, such as tumor location, size, and depth from the pleural surface. However, the types
of sublobar resection remain controversial . The selection of sublobar resections may differ in each
[32]
institution because each procedure has its own respective advantages and disadvantages for a precise
resection that can secure a sufficient surgical margin.

TECHNICAL PROBLEMS OF SUBLOBAR RESECTIONS
Localization of a small-sized tumor during wedge resection
Although wedge resection is a simple procedure, precise resection of the targeted tumor is challenging
when the tumor location is undetectable. For example, when the tumor is located deep within the
parenchyma, tumor detection is complicated because these tumors are not easily visualized or palpated by
the surgeon’s finger under thoracoscopy. Therefore, the localization and identification of small-sized GGO
lung tumors during thoracoscopic surgery is challenging, and various methods have been reported [33-36] .
The standard traditional method using a CT-guided hook wire involves the risk of complications such as