SAN DIEGO – General surgeons perform the majority of lung resections for cancer in the United States, yet lung cancer resections performed by thoracic surgeons had significantly lower in-hospital mortality rates than did those performed by general surgeons and cardiac surgeons, according to results of a large analysis of national hospital data.
When performing a lung cancer resection, thoracic surgeons performed lymphadenectomy significantly more often than did general surgeons and cardiac surgeons.
Dr. Michelle Ellis
"Lymph node status in lung cancer is the main determinant of stage, prognosis, and need for further therapy," Dr. Michelle Ellis said at the annual meeting of the Society of Thoracic Surgeons. "The performance of lymphadenectomy at the time of lung cancer resection can be considered a process measure of quality."
Previously published studies have demonstrated that general surgeons perform the majority of thoracic cases in the United States, while surgeons who specialize in thoracic surgery have lower perioperative morbidity and mortality. "Furthermore, patients who have their lung resection performed by a board-certified cardiothoracic surgeon specializing in general thoracic surgery have longer overall and cancer-specific survival," said Dr. Ellis of Oregon Health and Science University, Portland. "We hypothesized that the completeness of intraoperative oncologic staging at the time of primary lung cancer resection varies by surgeon specialty, and may explain the observed differences in outcome."
To test the hypothesis, Dr. Ellis, with the assistance of Dr. Paul H. Schipper and Dr. John T. Vetto, reviewed 222,233 primary lung cancer cases from the Nationwide Inpatient Sample from 1998 to 2007 who were treated surgically with limited lung resection, lobectomy, or pneumonectomy. The main outcome measure was the presence of lymphadenectomy or mediastinoscopy performed during the same admission.
The researchers divided the surgeons into three main groups based on their case mix of thoracic, cardiac, or other types of surgery. A thoracic surgeon was defined as someone who performed greater than 75% general thoracic surgery operations and less than 10% cardiac operations; a general surgeon was defined as someone who performed fewer than 75% thoracic operations and fewer than 10% cardiac operations, and a cardiac surgeon was defined as someone who performed greater than 10% cardiac operations.
Dr. Ellis reported that lung cancer resections were performed by general surgeons in 62% of cases, by cardiac surgeons in 35% of cases, and by thoracic surgeons in 3% of cases. The median annual case volume was 21 for thoracic surgeons, 23 for cardiac surgeons, and 8 for general surgeons.
In-hospital mortality rates for thoracic, cardiac, and general surgeons were 2.3%, 3.4%, and 4.0%, respectively. This translated into an odds ratio for in-hospital mortality of 1.33 for cases performed by cardiac surgeons and 1.55 for those performed by general surgeons.
Thoracic surgeons performed lymphadenectomy significantly more often than did their counterparts (73% vs. 55% for both cardiac and general surgeons). Thoracic surgeons also performed mediastinoscopy significantly more often (16% vs. 10% by cardiac surgeons and 11% by general surgeons).
Multivariate analysis revealed that patients were significantly less likely to undergo lymphadenectomy if they were in the lowest two quartiles of household income (odds ratio, 0.74); insured by Medicare (OR, 0.93); received their care at a rural hospital (OR, 0.60) or at an urban nonteaching hospital (OR, 0.74); or had their resection performed by a general surgeon (OR, 0.47) or by a cardiac surgeon (OR, 0.47).
"A patient was more than twice as likely to have a lymphadenectomy performed if the lung cancer resection was performed by a thoracic surgeon," Dr. Ellis said.
Next, the researchers assessed the impact of case volume on their multivariate model. They determined that for every doubling of thoracic surgery case volume, there was a significant increase in the likelihood that a lymphadenectomy would be performed (OR, 1.28). On the other hand, for every doubling of general surgery case volume, there was a significant decrease in lymphadenectomy rates (OR, 0.95). Doubling of cardiac surgery case volume did not affect lymphadenectomy rates.
"Lymphadenectomy rates for all surgeon groups did improve over the study period," Dr. Ellis said. "However, despite these improvements, cardiac and general surgeons still have lymphadenectomy rates significantly lower than [those of] cardiac surgeons. The next step is to ensure that all patients receive adequate staging of the mediastinum, possibly through disseminating knowledge, creating centers of excellence, or providing opportunities to learn the skills necessary to perform adequate lung cancer surgery."
She acknowledged certain limitations of the study, including the fact that it contains only single-admission information. "It also has limited cancer-specific data such as stage, and has no mechanism for long-term follow-up," she said. In addition, surgeons are anonymous in the database, so board certification could not be determined.