Recent advances in the vibrational spectroscopic diagnosis of non-small cell lung cancer

Lung cancer is the leading cause of cancer deaths worldwide accounting for 1.69 million deaths in 2015. Studies have indicated a 5 year survival rate of 8%–15% in western countries, although a survival rate as low as 1% has been demonstrated for late stage diagnosis. With the advent of targeted therapies, it is imperative to accurately differentiate non-small cell lung cancer (NSCLC) subtypes in order to ensure efficacy of treatment for patients. Immunohistochemistry and molecular techniques for the diagnosis of NSCLC are increasingly part of the diagnostic algorithm and clinical work-up of lung cancer patients, however due to the limitation of small sample size, overlapping morphological features and molecular characterisation, differential diagnosis of NSCLC still proves challenging. Vibrational spectroscopy has shown promising results for the detection of a variety of cancers and a limited number of studies have focused on lung cancer. Yet to date there has been no published evaluation of vibrational spectroscopy on cytology bronchoscopy samples which may eliminate the necessity for an invasive biopsy procedure. Following an introduction to the epidemiology and etiological factors associated with NSCLC, currently used diagnostic methods and their limitations are presented. A thorough review of Raman and FTIR spectroscopic methods in lung cancer diagnosis is then presented. On review of the literature, vibrational spectroscopy offers an alternative or adjunct diagnostic method to be applied in bronchoscopy cytology samples.