Assessing the number of annual lung cancer resections performed in the United States

Introduction

Every year, over 238,000 individuals in the United States (U.S.) are diagnosed with lung cancer (1). Surgery offers the best chance at cure for most patients with early-stage disease. However, the number of annual lung cancer resections performed in the U.S. has not previously been assessed. The objectives of this study are: (I) to assess the percentage of lung cancer cases in the U.S. captured by the National Cancer Database (NCDB) in 2016 and 2017; (II) to estimate the total number of lung cancer resections performed in the U.S. in 2016 and 2017; and (III) to estimate the number of each type of resection performed in 2016 and 2017 in the U.S. We present this article in accordance with the TREND reporting checklist (available at https://shc.amegroups.com/article/view/10.21037/shc-22-7/rc).

Methods

Data source

The NCDB is a clinical oncology database and a joint project of the Commission on Cancer of the American College of Surgeons and the American Cancer Society. The NCDB currently captures 70% of all newly diagnosed malignancies in the U.S. annually, from more than 1,500 affiliated facilities (2). For the years of study inclusion (2016-2017), clinical and pathological staging information is directly recorded in the NCDB using American Joint Committee on Cancer (AJCC) 6^th and 7^th edition Tumor, Nodes, and Metastases (TNM) Staging (3). However, in the present study, the staging was reclassified using best available data according to AJCC 8^th edition criteria.

Study design

This study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This study was deemed exempt from review by the Massachusetts General Hospital Institutional Review Board (No. 2020P004110; 02/02/21). Informed consent was not required because all data analyzed was deidentified. Patients diagnosed with non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) in the 2017 NCDB Participant User Data File who were diagnosed at or underwent treatment at a Commission on Cancer (CoC)-accredited cancer program from 2016 to 2017 were identified for inclusion, using the International Classification of Diseases for Oncology, 3^rd edition histology and topography codes.

Within this population, we identified patients who underwent surgical resection for lung cancer. We estimated the annual number of lung cancer resections and the number of each type of resection performed in 2016 and 2017 using the indirect multiplier method described below. The year 2017 was chosen for analysis because it is the most recent, available year of data in the NCDB. We also included the year 2016 in our analysis because mortality data were not available in the NCDB for the year 2017 at the time of this writing.

Statistical analysis

Indirect multiplier method

We employed a previously described indirect multiplier method (4) to estimate the annual number of lung cancer resections performed in the U.S. Briefly, the indirect multiplier method uses two data sources to estimate population size: benchmark data and multiplier data. Benchmark data provides a count of the population that meet a certain criterion. Multiplier data provides a proportion of the population that meet the same criterion from a separate sample (4). In this study, benchmark data include the number of lung cancer resections documented in the NCDB during the study period. Multiplier data indicate the proportion of all lung cancer cases captured within the NCDB. The reciprocal of the proportion is the multiplier, which can be used to adjust benchmark data to provide a national estimate of the number of lung cancer resections (5).

Benchmark data was obtained from the NCDB. With regard to the multiplier data, we estimated the proportion of incident lung cancer cases in the U.S. that were captured by the NCDB for each year of the study. We compared the number of lung cancer cases in the NCDB to the number of lung cancer cases in the United States Cancer Statistics (USCS) Data Set (6). Data in the USCS were provided by central cancer registries participating in Centers for Disease Control and Prevention (CDC)’s National Program of Cancer Registries (NPCR) and/or National Cancer Institute (NCI)’s Surveillance, Epidemiology, and End Results (SEER) Program and submitted to CDC and NCI in 2019. Of note, the USCS does not capture in situ (non-invasive) lung cancer cases. Accordingly, we excluded in situ (non-invasive) lung cancer cases in the NCDB. The multiplier was calculated by dividing the number of incident lung cancer cases in the NCDB by the number of incident lung cancer cases in the USCS each year and taking its reciprocal.

We used the indirect multiplier method to assess the number of annual lung cancer resections and the number of each type of lung cancer resection performed in the U.S. each year. We estimated the number of wedge resections, segmentectomies, lobectomies and bilobectomies, bronchial sleeve resection, extended lobectomies (with chest wall, pericardium, or diaphragm), pneumonectomies, and extended pneumonectomies performed each year in the U.S. Changes in the number of operations performed each year were assessed using univariate Poisson regression. Statistical analysis was performed using Stata/MP software, version 13.1 for PC (StataCorp, College Station, TX, USA).

Results

In 2016, there were 145,257 lung cancer cases documented in the NCDB and 222,894 incident lung cancers in the USCS. In 2017, there were 143,841 lung cancer cases in the NCDB and 221,121 incident lung cancers in the USCS. In the NCDB, 37,128 patients and 36,822 patients underwent lung cancer resections in 2016 and 2017, respectively. Baseline characteristics and perioperative outcomes of patients in the NCDB, stratified by operation type, are detailed in Tables S1-S4.

The NCDB captured 65.2% and 65.1% of incident lung cancer cases in 2016 and 2017 that were recorded in the USCS database. Using the indirect multiplier method, we estimate there were approximately 57,000 lung cancer resections performed in the U.S. in 2016 and over 56,600 lung cancer resections performed in the U.S. in 2017. In 2016, we estimate there were 25,893 (69.7%) lobectomies and bilobectomies, 7,017 (18.9%) wedge resections, 1,704 (4.6%) segmentectomies, 1,155 (3.1%) pneumonectomies, 1,044 (2.8%) extended lobectomies, 45 (0.1%) bronchial sleeve resections, and 16 (0.04%) extended pneumonectomies performed in the U.S. (Table 1). In 2017, we estimate there were 26,008 (70.6%) lobectomies and bilobectomies, 6,692 (18.2%) wedge resections, 1,814 (4.9%) segmentectomies, 1,017 (2.8%) pneumonectomies, 927 (2.5%) extended lobectomies, 52 (0.1%) bronchial sleeve resections, and 24 (0.1%) extended pneumonectomies performed in the U.S. (Table 2).

From 2016–2017, the number of lung cancer resections performed in the U.S. did not significantly change (56,992 to 56,639, P=0.24). In an analysis stratified by surgery type, there was a 6.7% (2,615 to 2,789, P=0.007) increase in case volume for segmentectomy from 2016–2017. Conversely, there was a 4.5% (10,767 to 10,287, P=0.001) decrease in the case volume for wedge resection, 11.8% (1,772 to 1,563, P=0.001) decrease in the case volume for pneumonectomy, and 11.0% (1,602 to 1,425, P<0.001) decrease in case volume for extended lobectomy from 2016. The case volumes for lobectomy and bilobectomy (39,732 to 39,981, P=0.29), bronchial sleeve resection (69 to 80, P=0.42), and extended pneumonectomy (25 to 37, P=0.23) did not significantly change from 2016–2017.

Discussion

In this national analysis, using indirect multiplier methods, we estimated the number of lung cancer resections performed in the U.S. in 2016 and 2017. Each year, we estimate there are approximately 56,000–57,000 lung cancer resections performed in the U.S. Lobectomy is the most common operation and the second most common operation is wedge resection.

The main strength of this study is that we used the NCDB to estimate the total number of annual lung cancer resections in the U.S. The NCDB is the largest clinical database in the U.S. In addition to its much larger size, the NCDB has several advantages over other administrative databases such as the Nationwide Inpatient Sample. Administrative databases are based on hospital discharge records, have only limited clinical data, and can be subject to reimbursement bias. Moreover, a previous study has shown that there are significant inaccuracies in the documentation of surgical treatments and a systematic underreporting of procedures in administrative databases (7). Unlike administrative databases, data in the NCDB are obtained from all available components of the medical record and are manually abstracted by trained registrars (8). Furthermore, the NCDB contains information on a large number of clinical data, including patient and tumor characteristics, cancer staging, type of first course treatment administered, use of neoadjuvant and adjuvant treatments, and short- and long-term overall survival.

There are several limitations to this study. Importantly, the accuracy of indirect multiplier methods is dependent on the quality of the existing datasets. Thus, one potential limitation would be discrepancies between the datasets used to generate the multiplier. Of note, Veteran Administration (VA) Hospitals reporting data are excluded from the 2017 NCDB participant user file and an unknown number of VA hospitals report data to the USCS (9). Since the United States Cancer Statistics Database includes some, but not all, data from VA hospitals, it is possible that the number of lung cancer cases captured in the United States Cancer Statistics Database slightly underestimates the total number of lung cancer cases diagnosed in the U.S. each year. As such, it is possible that the percentage of lung cancer cases captured in the NCDB was overestimated, leading to an underestimation of the total number of lung cancer resections performed each year. Due to the small number of lung cancer cases from the VA that are not reported to the United States Cancer Statistics Database, the extent of this underestimation should be very small. Another potential limitation would be biases in the benchmark dataset (the number of resections in NCDB). CoC-accredited hospitals that report data to the NCDB are generally larger and offer a greater range of treatment services, potentially resulting in a higher resection rate among patients in the NCDB and an overestimate of the number of resections (10). Lastly, the NCDB does not reliably capture pulmonary resections for metastatic disease (e.g., metastasectomy for colon cancer that has metastasized to the lung) and does not capture resections for benign disease (2,8). In this regard, our analysis may have underestimated the number of resections in the U.S.

Conclusions

In conclusion, this is the first study to use a national clinical oncology database to estimate the total number of lung cancer resections in the U.S. Every year, we estimate there are 56,000–57,000 lung cancer resections performed in the U.S., with lobectomy being the most common operation.

Acknowledgments

The data used in the study are derived from a de-identified NCDB file. The American College of Surgeons and the CoC have not verified and are not responsible for the analytic or statistical methodology employed, or the conclusions drawn from these data by the investigator.

Funding: None.

Footnote

Reporting Checklist: The authors have completed the TREND reporting checklist. Available at https://shc.amegroups.com/article/view/10.21037/shc-22-7/rc

Peer Review File: Available at https://shc.amegroups.com/article/view/10.21037/shc-22-7/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://shc.amegroups.com/article/view/10.21037/shc-22-7/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This study was deemed exempt from review by the Massachusetts General Hospital Institutional Review Board (IRB#: 2020P004110; 02/02/21). Informed consent was not required because all data analyzed was deidentified.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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