The question of parenchyma-sparing resection in bronchial carcinoma has been intensively discussed for some time. In the revised S3 guideline for lung carcinoma, anatomical segment resection is now recommended for the first time for tumors < 2cm in stages I and II as an alternative and equivalent therapy option to lobectomy. In cases of limited operability, anatomical segment resection is also the best oncological therapy option for larger tumors in stages I and II. (1)
Extended Tumor Criteria for Limited Resection
In international literature and with the conclusion of some major studies in 2022, additional important radiological criteria were evaluated besides tumor size. Particularly, the reduction in transparency around the tumor site (ground-glass opacity; GGO) and the derived ratio to the tumor nodule (Consolidation to Tumor Ratio; C/T-Ratio) appear to be promising indicators.
In Japan, a large multicenter study including over 1100 patients demonstrated that segment resection showed improved overall survival compared to lobectomy for patients in stage IA UICC with a C/T-ratio > 0.5. (2)
In another multicenter study, considering GGO typing, even a wedge resection was shown to be an oncologically equivalent first-line therapy. (3) This seems plausible since a morphologically dominant GGO strongly correlates with the presence of a low-grade adenocarcinoma. (4)
Another prognostic factor is the presence of Spread Through Air Spaces (STAS). This involves tumor spread through the air spaces. While further research and studies on the biological mechanism, genetics, and significance in oncological therapy are needed, detection in the pathological specimen is likely an exclusion criterion for limited resection. (5)
Outlook
Following the completion of several major studies in recent years, the indication for anatomical segment resection is also expanded in the updated German S3 guideline. Besides tumor size, no further criteria for patient selection have been defined so far. It is hoped that after the completion of some ongoing and future studies, criteria can be defined that will further reduce the extent of parenchyma resection (wedge resection, anatomical segment resection, or lobectomy) while achieving the best possible oncological outcome.
ICG in Thoracic Surgery
A key point in the successful execution of a segment resection is the intraoperative visualization of segment boundaries. Here, the method using the fluorescent dye ICG (Indo-Cyanine Green), which has been used in other specialties for some time, is experiencing a small renaissance in thoracic surgery. A study showed that the visualization of segment boundaries with ICG is more effective than selective ventilation and independent of external influences such as chronic obstructive pulmonary disease. (6) In 2022, a Chinese expert group recommended the routine use of ICG. (7)