Lung cancer treatments are evolving rapidly and now offer new technologies and research-proven procedures. Central to these advances, however, is the foundational principle of performing high-quality, evidence-based surgery. Surgical resection remains the desired treatment for functionally fit patients with Stage 1 non-small cell lung cancer (NSCLC). As a result, process-based surgical quality metrics (QMs) are critical for optimizing long-term outcomes following curative-intent resection.
A new study by researchers at the VA St. Louis Health Care System and the Washington University School of Medicine in St. Louis developed a surgical QM scoring system-the Veterans Affairs Lung Cancer Operative quality (VALCAN-O) score-to determine if the practical method of scoring surgical quality could improve overall survival (OS) and disease-free survival (DFS) in U.S. veterans undergoing curative-intent surgery for early-stage NSCLC (JAMA Surg 2023; doi: 10.1001/jamasurg.2022.6826).
To answer the question, the researchers conducted a retrospective cohort study using a uniquely compiled dataset of de-identified medical records maintained by the U.S. Veterans Health Administration. Drawing on contemporary treatment guidelines established by the National Comprehensive Cancer Network and other cancer groups, the researchers defined five surgical QMs:
1. timely surgery (within 12 weeks of radiographic suspicion);
2. use of a minimally invasive approach;
3. anatomic resection (via lobectomy or segmentectomy);
4. adequate lymph node sampling (>=10 nodes); and
5. negative surgical margin.
Next, the team utilized a multivariable Cox proportional hazards model to develop a surgical quality score that reflected the relationship between these QMs and OS, which was further validated in a cohort of patients using data from the National Cancer Database (NCDB). The researchers also examined the association between this surgical quality score and DFS.
The researchers examined information involving 9,628 U.S. veterans (mean age, 67.6 years; 96.4% men; 58.4% smokers at the time of surgery) with clinical Stage I NSCLC who underwent definitive surgical treatment between 2006 and 2016. The data were analyzed from April 1 to September 1, 2022. An integer-based VALCAN-O scoring system of 0 (no QMs met) to 13 (all QMs met) was constructed to reflect the correlation of surgical quality metrics and risk-adjusted OS. The association of the quality score with DFS was also analyzed.
After median interquartile range (IQR) follow-up of 6.2 years (range, 2.5-11.4), QMs were met as follows: 68.9 percent (n=6,633) received surgery within 12 weeks of diagnosis, 41.4 percent (n=3,986) had surgery that used a minimally invasive approach, while 76.6 percent (n=7,375) had anatomic resection (71.1% [n=6,843] with lobectomy and 5.5 percent [n=532] with segmentectomy). The best performance was in achieving negative margins, which was accomplished in 96.7 percent (n=9,312) of surgeries. In contrast, the worst performance was in sampling, where just only 34.1 percent (n=3,278) had adequate (10 or more) nodes sampled.
The median IQR OS was 86.8 months (37.8-149.6) in the highest score quintile versus 25.3 months (7.1-45.8) in the lowest score quintile. Recurrence was detected in 23.6 percent (n=2,268) of patients. DFS was associated with higher surgical quality score (aHR: 0.494, 95% CI: 0.245-0.997).
The median (IQR) OS differed substantially between the score categories (0-5 points, 2.6 years; 6-8 points, 4.3 years; 9-11 points, 6.3 years; 12-13 points, 7 years; P<.001). Furthermore, risk-adjusted DFS increased in a stepwise manner between the score categories (6-8 vs. 0-5 points, multivariable-adjusted HR [aHR]=0.62; 95% CI: 0.48-0.79; 12-13 vs. 0-5 points, aHR=0.39; 95% CI: 0.31-0.49; P<.001).
The scoring system was validated using data from a cohort of 107,674 non-veteran patients with early-stage NSCLC from the NCDB. The score remained associated with OS: 0-5 points, 3.8 years; 6-8 points, 5.9 years; 9-11 points, 7.6 years; 12-13 points, 8.7 years; overall P<.001).
Oncology Times connected with the study's lead author, Brendan T. Heiden, MD, MPHS, for his thoughts on the findings. He is a resident physician in the Department of Surgery and a research fellow in the Division of Cardiothoracic Surgery at Washington University School of Medicine in St. Louis.
Oncology Times: Beside the set of five quality metrics, did the study control for other variables that could influence OS in veterans with early-stage NSCLC?
Heiden: "Yes, the model controlled for relevant patient demographic-, treatment-, and tumor-related characteristics that could also affect overall survival in early-stage NSCLC. The VA is a unique database given the relatively exhaustive availability of important covariates."
Oncology Times: Did the study find any disparities in surgical quality metric adherence and OS between different subgroups of U.S. veterans with early-stage NSCLC?
Heiden: "We did not explicitly assess whether VALCAN-O scores differed significantly between different subgroups of patients. However, prior work from our group has found disparities in certain quality metrics, such as the likelihood to receive timely surgery. We did notice wide variation in adherence to QMs based on geographic location. That said, we were impressed by the significant improvement in the quality of lung cancer surgeries (i.e., VALCAN-O scores) across the U.S. over the last decade."
Oncology Times: What is the generalizability of the study's findings to other populations with early-stage NSCLC, both veterans and non-veterans?
Heiden: "The score was developed in a uniquely compiled cohort of nearly 10,000 veterans with lung cancer. The score was further validated in a cohort including over 100,000 non-veteran patients with early-stage NSCLC receiving surgical treatment. The score performed similarly in both cohorts of patients, suggesting that it is likely generalizable to several different patient populations."
Oncology Times: Based on the findings, what are some recommendations for improving surgical quality metric adherence to improve OS in U.S. veterans with early-stage NSCLC?
Heiden: "Our study demonstrates that adherence to surgical quality metrics can dramatically impact long-term outcomes after lung cancer surgery. Further efforts are needed to ensure that these guideline-concordant treatment parameters are followed as frequently as possible in surgical practice settings across the U.S. The thoracic oncology community should be applauded, as our results demonstrated a substantial improvement in surgical quality measures over the last decade. These quality metrics will continue to be important, especially as exciting new treatments continue to transform outcomes among patients with early-stage lung cancer."
Dibash Kumar Das is a contributing writer.