Three studies were recently presented at the 95th Annual Meeting of the American Association for Thoracic Surgery addressing the issue of venous thromboembolism (VTE) after lung cancer surgery. VTE refers to a common condition in which a blood clot (or thrombus) travels within a vein. It includes two conditions: i) deep vein thrombosis (DVT), in which the blood clot is found in deep veins of the leg, being characterized by swelling, fever, localized warmth and tenderness, and ii) pulmonary embolism (PE), a life-threatening condition in which the blood clot travels to the lungs, causing sudden breathing problems, rapid heart and breathing rates, cough with blood, chest pain and fainting.
It has been suggested that patients who undergo lung cancer surgery have a higher risk of developing VTE than previously thought, increasing the risk of postoperative complications and mortality.
One of the studies led by Dr. Yaron Shargall, Head of the Division of Thoracic Surgery at McMaster University, Canada presented the first prospective assessment of VTE incidence after oncologic lung resection in a cohort of 157 patients. Patients were given heparin-based blood thinners and mechanical VTE preventative treatment in the period between surgery and hospital discharge. After a month, researchers found a 12.1% VTE incidence rate (14 PE events, 3 DVT events and one combined PE/DVT). Only four patients diagnosed with VTE experienced disease symptoms. The 30-day mortality rate for the 157 patients was found to be 0.64%, whereas this rate increased to 5.2% among patients who had VTEs.
“This study shows that a significant proportion of lung cancer surgery patients are at risk of VTE, and indicates a need for future research into minimizing the occurrence of DVT and PE. It is possible that extended use of blood thinners beyond hospital discharge may reduce the number of patients who experience these life-threatening events and may help to reduce the rates of death after lung surgery,” concluded Dr. Shargall in a news release.
A second study presented by Dr. Siva Raja from the Cleveland Clinic focused on the impact of post-operative screening on VTE incidence in 112 patients who underwent pneumonectomy (surgical lung removal). Results were compared to a previous study involving 336 similar patients who were not submitted to VTE screening. Researchers found that VTE incidence was three times higher in the screened group (8.9%) in comparison to the group not screened (3.0%), and more than twice as high during the 30-day postoperative period (13% vs. 5.0%). The team found that the risk of VTEs peaks six days after surgery.
“We find that a large proportion (50%) of VTEs occurred prior to the time of discharge, and the risk of developing symptomatic VTE remained elevated for 30 days. It is possible that the prevalence of VTE may be even higher should a comprehensive serial screening program be initiated,” noted Dr. Raja. Since 2006, routine screening for VTE upon pneumonectomy, and before hospital discharge, is performed at Cleveland Clinic.
The third study, presented by Dr. Virginia R. Litle from Boston University School of Medicine, focused on the question of how can post-surgical lung cancer patients at higher risk of developing a VTE be identified. “The Caprini Risk Assessment Model (RAM) is used as a VTE risk assessment tool in other surgical specialties, including general, vascular and plastic surgery as well as gynecologic oncology,” said Dr. Litle “but it has not been applied in thoracic surgery.”
Researchers analyzed 232 patients who had undergone lung resection and found a 60-day postoperative VTE incidence of 5.17% (12 patients). Patients who developed VTEs were found to exhibit a mean Caprini score significantly higher than patients without VTE reports. “This is the first study to demonstrate the predictive ability of the Caprini RAM in post-operative lung resection patients,” concluded Dr. Litle. “This risk assessment scoring system can be used to determine which lung resection patients may potentially benefit from preventive blood thinner therapy after discharge. We have measured these scores and found that a prolonged course of enoxaparin sodium (Lovenox) or other blood thinners may improve the risk of dying of this complication after a lung cancer operation.”