Study confirms uncertain resection margin status proposed by IASLC
UK researchers confirm the International Association for the Study of Lung Cancer (IASLC)’s proposed criteria for uncertain resection margin status, R(un), in residual tumour classification.
Residual tumour (R) classification describes the tumour status following treatment. The R classification, therefore, reflects the treatment’s effectiveness, which impacts prognosis and potentially further treatment. Considering the important implications of R classification, the researchers undertook this study to analyze R status criteria using data collected from the IASLC Lung Cancer Staging Project. Mr John G Edwards, consultant thoracic surgeon, University of Sheffield, UK, presented the study findings at the IASLC 18th World Conference on Lung Cancer (WCLC) in Yokohama, Japan.
“The IASLC Lung Cancer Staging Project has been going on for many years. We are analyzing the data set as carefully as we can to look at the markers of uncertain resection as previously being proposed,” said Edwards.
The data analyzed included information on full R status and survival data of 14,712 patients undergoing NCSLC surgery. The researchers evaluated R status criteria and other relevant data including the number of N2 stations explored, lobe-specific systematic lymph node dissection (SLND), extra-capsular extension (ECE), status of the highest station, bronchial carcinoma in situ (cis) at bronchial resection margin (BRM) and pleural lavage cytology (PLC). Additionally, the researchers designated and tested revised categories of R0, R(un), R1 and R2 for survival impact.
In 2005, researchers proposed the criteria – for those cases where otherwise the tumours were free in terms of the positivity of margins but where there were criteria that seemed to potentially give rise to less than certain resection margin which they termed an uncertain resection margin and those were cases where the intraoperative lymph nodes staging was less vigorous than the standard of systematic lymph node dissection or lobe-specific systematic lymph node dissection; the highest lymph node is positive; the bronchial resection margin shows carcinoma in situ rather than invasive carcinoma; and pleural lavage cytology is positive (R1 cy+) – this is where saline is instilled into the cavity at the beginning or the end of the operation and the lavage is suctioned and sent for cytological analysis. [Lung Cancer 2005;49:25–33]
The researchers used the 8th Edition Database, which started off as 94,000 cases but there were 14,712 cases for whom full data were available and of which, 85 percent were from Japan and the rest from 50 institutions around the world. Cases were assigned to the uncertain status according to the criteria published in 2005.
“When looking at the conventional R status, we could see that the R0 cases did much better as one would expect,” said Edwards. However, the numbers were relatively small with R1 and R2 cases in the database and there was no significant difference between those two but that may be due to the relatively small size of the study.
Researchers found that the vast majority of the cases that were reassigned to the uncertain categories was due to inferior dissection and the technique being less vigorous. When they looked at the R status in total and the node negative cases, there wasn’t quite a significant difference. However, in patients with a node positive status there was a significant drop in survival in the R(un) cases which accounted for 20-month difference in median survival and a 10 percent difference in 5-year survival (Hazard ratio, HR: 1.27).
“The numbers in the other categories were quite small and hence, that leads to the need in future for getting very high-quality data into the database,” said Edwards.
Good lymph node dissection before high-quality surgery is important to show that the survival rates on an institutional basis are the best. An assessment of the quality of surgery is being done in the LungArt and PEARLS trials and the researchers propose that these techniques are included in other studies as well.