LIFE-Lung Bronchoscopy in Patients at Risk for Developing Lung Cancer

The North American Lung Cancer Study Group showed that Stage I (T1,N0,M0) non small cell lung carcinoma patients who have undergone complete surgical resection have a 60-70% five-year survival but have a 3.6% per year risk of developing a second lung primary cancer. Data from the Mayo Clinic on patients that underwent surgical resection for sputum cytology positive but radiologically occult lung cancer found that second primary lung cancers occurred at a rate as high as 5% per year in this patient population. In a collective review of 1406 patients with occult or stage I completely resected lung carcinomas, the incidence of second-primary lung cancers was 11.4% (range 3-30%). The mortality from second-primary lung carcinomas in surgical patients is much higher than for the first tumor because treatment is both more limited and complicated as a consequence of their prior lung resection. Second NSCLC primaries are a particularly vexing treatment dilemma in patients who have undergone a prior curative, surgical resection because of their limited, residual pulmonary reserve.

White light bronchoscopy (WLB) has been shown to be a useful tool in localizing radiographically occult lesions. However, Woolner et al. demonstrated that only 29% of carcinoma in situ (CIS) and 69% of micro-invasive tumors are identified by experienced bronchoscopists. In 1996 an endoscopic lung imaging system developed by the British Columbia Cancer Research Centre in conjunction with Xillix Technologies Corp., known as the LIFE-lung Fluorescence Endoscopy System was approved by the FDA. LIFE-lung bronchoscopy is performed with a helium-cadmium laser using blue light @ 442 nm for illumination and allows visualization of these differences in normal and abnormal tissue autofluorescence. Lam and others have shown that the tissue autofluorescence spectra of areas of dysplasia and carcinoma in situ differ significantly from those of normal bronchial tissues. Specifically, LIFE Bronchoscopy improved sensitivity of detection of metaplasia and dysplasia by 171% over current WLB. LIFE bronchoscopy's sensitivity for the detection of CIS is 500% greater than that of standard WLB.

Fluorescence bronchoscopy using the LIFE system is identical to standard flexible bronchoscopy except that it utilizes blue light (from a Helium-Cadmium light source) in contrast to white light (commonly emitted from a Xenon or Halogen light source). Both fluorescent and reflected light are produced when the bronchial surface is illuminated by visible light, the difference is that with the LIFE-lung system, the image is reconstructed from emitted fluorescent light instead of from light reflected off of the bronchial surface. Emitted fluorescence and reflective light are separated by appropriate filters.