Lymph Node Harvest, Upstaging After Lobectomy for NSCLC Linked to Hospital Volume
Key findings
- This study investigated institutional-level factors associated with differences in nodal harvest and nodal upstaging after lobectomy for non–small-cell lung cancer (NSCLC)
- Overall, average nodal harvest was higher at high-volume centers than low-volume centers, but 44% of low-volume centers averaged ≥10 lymph nodes per lobectomy and 25% of high-volume centers averaged <10 nodes
- Concordance of clinical nodal status and pathologic nodal status at the time of lobectomy was inversely associated with harvest of ≥10 nodes but was not associated with the volume of lobectomies performed at a center
- A trend toward increased nodal upstaging at low-volume centers compared with medium- and high-volume centers became significant in a subgroup analysis of patients with clinical T2 disease, clinical N1 disease, or centrally located tumors
- Annual lobectomy volume is likely to be just one of many important factors in lymph node harvest in patients with NSCLC
Robust lymph node harvest during lobectomy for patients with non–small cell lung cancer (NSCLC) allows accurate staging and is associated with improved clinical outcomes.
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Previous research at Massachusetts General Hospital showed significant variation between institutions in the accuracy of clinical nodal staging, from 90% to below 70%.
Henning A. Gaissert, MD, visiting surgeon in the Division of Thoracic Surgery at Massachusetts General Hospital and chief of Thoracic Surgery at Newton-Wellesley Hospital within the Mass General Brigham system, Brooks V. Udelsman, MD, MHS, graduate of the Mass General Surgical Residency Program and now at the Yale School of Medicine, and colleagues recently explored causes of that variation by reviewing the Society of Thoracic Surgeons General Thoracic Surgery Database.
In The Annals of Thoracic Surgery, they say a higher volume of lobectomies for NSCLC at a center is associated with increased nodal harvest, but 25% of high-volume centers average <10 lymph nodes per procedure.
Methods
The team identified 43,597 patients who underwent a first-time lobectomy for NSCLC, with staging that included PET and CT, between 2012 and 2019. They were treated at 305 centers, which were grouped into tertiles by average annual lobectomy volume:
- Low-volume centers (n=102)—six lobectomies/year; 6% of all lobectomies in this study
- Medium-volume centers (n=102)—20/year; 24% of all lobectomies
- High-volume centers (n=101)—43/year; 70% of all lobectomies
Primary Outcome
The primary outcome was mean center-level nodal harvest ≥10 nodes per lobectomy. Average nodal harvest increased in a stepwise fashion with center volume, as did the percentage of centers meeting the primary outcome:
- Low-volume centers—mean, 10 nodes; 44% of centers met the ≥10-node criterion
- Medium-volume centers—mean, 12.5 nodes; 71% met the criterion
- High-volume centers—mean, 12.8 nodes; 75% met the criterion
In multivariable analysis, the average center harvest of ≥10 nodes was strongly associated with:
- Status as a medium-volume center (OR, 2.94; P<0.01)
- Status as a high-volume center (OR, 3.82; P<0.001)
Secondary Outcome
The secondary outcome was the center-level rate of concordance between clinical N (cN) and postoperative pathologic N (pN). The overall concordance was 83% and did not significantly differ on the basis of center volume.
In multivariable analysis, the rate of cN and pN concordance was most strongly associated with an average harvest of ≥10 nodes (coefficient, −4.33; P<0.01).
Subgroup Analyses
The team studied a subgroup of 17,547 patients with high-risk NSCLC (clinical T2 disease, clinical N1 disease, or centrally located tumor). The proportion of centers that harvested ≥10 nodes on average was:
- Low-volume centers—49%
- Medium-volume centers—77%
- High-volume centers—85% (P<0.001)
Correspondingly, the rate of upstaging between cN and pN was higher at high-volume centers (29%) than at low- and medium-volume centers (25% and 23%; P=0.047).
Commentary
The increase in nodal upstaging among centers averaging ≥10 nodes—among both low- and high-volume centers—indicates the potential to miss occult nodal disease if inadequate sampling is performed. That, in turn, could have long-term consequences for patients through the postponement of adjuvant therapy.
The decrease in concordance with increased nodal sampling indicates the presence of occult nodal disease that may be missed with an inadequate nodal harvest.
At the time of the study, sampling of ≥10 nodes was a surveillance marker of the American College of Surgeons Commission on Cancer (ACS CoC). In contrast, the National Comprehensive Cancer Network (NCCN) recommended sampling at least three mediastinal stations and at least one hilar station, as it does today. In 2020, the ACS CoC adopted quality standard 5.8, which matches the NCCN recommendation.
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