Diagnostic Strategy May Help Determine Stage Of Lung Cancer More Accurately
A preoperative testing strategy combining two procedures may help improve the accuracy of determining the stage of lung cancer, according to an article in the August 24/31 issue of JAMA.
Up to 40 percent of thoracotomies (surgical incision of the chest wall often involving surgery of the lung) performed for non-small cell lung cancer (NSCLC) are reported to be unnecessary, predominantly due to inaccurate preoperative detection of lymph node metastases, according to background information in the article. Accurate preoperative staging is important in identifying those patients who will benefit from surgical resection (removal of tissue). Currently available staging techniques have limited accuracy in selecting those lung cancer patients without regional lymph node metastases.
Transesophageal ultrasound-guided fine needle aspiration (removal of cells or tissue through a needle) (EUS-FNA) is a minimally invasive and safe technique than can target different lymph node stations and is complementary to mediastinoscopy (examination of the mediastinum [a part of the middle of the thoracic cavity] using a special scope that is inserted through an incision above the sternum) in its diagnostic reach. With EUS-FNA, an ultrasound transducer (a transmitter and receiver of ultrasound information) incorporated on top of an endoscope enables the investigator to visualize and insert the aspiration needle into mediastinal lymph nodes under real-time ultrasound guidance. The EUS-FNA examination has a sensitivity of 88 percent and a specificity of 91 percent in analyzing mediastinal lymph nodes. To date it is not known how EUS-FNA compares with mediastinoscopy, nor to what extent the combination of EUS-FNA and mediastinoscopy improves preoperative staging.
Jouke T. Annema, M.D., Ph.D., of Leiden University Medical Center, Leiden, the Netherlands, and colleagues conducted a study to determine whether lung cancer staging by EUS-FNA in addition to mediastinoscopy improved preoperative staging compared with staging by mediastinoscopy alone. During a 3-year period (2000-2003), 107 patients with potential resectable non-small cell lung cancer underwent preoperative staging by both EUS-FNA and mediastinoscopy. Patients underwent thoracotomy with tumor resection if mediastinoscopy was negative. Surgical-pathological staging was compared with preoperative findings and the added benefit of the combined strategy was assessed. The multicenter study was performed in 1 referral and 5 general hospitals in the Netherlands.
The researchers found that the combination of EUS-FNA and mediastinoscopy identified more patients with tumor invasion or lymph node metastases (36 percent) compared with either mediastinoscopy alone (20 percent) or EUS-FNA (28 percent) alone. This indicated that 16 percent of thoractomies could have been avoided by using EUS-FNA in addition to mediastinoscopy. However, 2 percent of the EUS-FNA findings were false-positive.
"The results can be explained by the fact that EUS-FNA and mediastinoscopy have a complementary reach in assessing regional lymph node stations and in the ability of EUS-FNA to detect mediastinal tumor invasion," the authors write. "Our findings are directly applicable to clinical practice."
"Overall, mediastinoscopy and EUS-FNA have inherent limitations and they should be viewed as complementary in the regional staging of NSCLC. These preliminary findings suggest that EUS-FNA, a novel, minimally invasive staging procedure for lung cancer, may improve the preoperative staging due to the complementary reach of EUS-FNA in detecting mediastinal lymph node metastases and the ability to assess mediastinal tumor invasion. However, the occurrence of false-positive EUS-FNA findings in selected cases needs to be further investigated," the researchers conclude.
(JAMA. 2005;294:931-936) - Chicago