Advances in the Treatment of Lung Cancer
The development of new protocols may prove to be of benefit to patients with asbestos-related lung cancer. The earlier lung cancer is diagnosed, the better. Research into the effectiveness of fluorescence bronchoscopy (FB) and photodynamic therapy (PDT) is producing good results. Fluorescence bronchoscopes detect differences between normal and abnormal tissues enabling doctors to locate pre-invasive lesions and invasive carcinomas at an early stage. Researchers at the Bronchology Unit of Wythenshawe Hospital are "currently evaluating the sensitivity and specificity of the technique using high risk population groups in whom lung cancer is the single commonest cause of death; these include patients with asbestosis and survivors from treated lung and laryngeal carcinoma." A programme at the Yorkshire Laser Centre (YLC) to assess the comparative efficacy of White-light and FB in identifying cancer affecting the bronchial tree is on-going; four categories of high-risk individuals, including those with a history of exposure to asbestos, are eligible. The development of effective primary screening tests is essential as FB is too invasive and expensive a procedure to be used for blanket testing. Sputum screening, using molecular genetic and immunocyto-chemical markers to select potential patients, is one of the techniques being investigated.
Although some experts remain sceptical, the clinical value of photodynamic therapy (PDT) seems much more apparent. With adequate precautions, PDT is a safe method for the durable palliation of symptoms in patients with advanced obstructive tumours. According to Consultant Respiratory Physician Philip Barber, PDT "involves the intravaneous administration of a systemic sensitiser which is selectively taken up by tumour tissue, followed by the application of laser light of a specific wavelength… Tumour regression can be obtained in progressive or relapsed disease following conventional treatment. It is also a potentially repeatable therapy with excellent healing characteristics, and may be uniquely suitable for the early treatment of metachronous primary disease in high risk populations." A joint study undertaken by the YLC and the Universities of Hull and Leeds concluded that "PDT is effective in palliation of inoperable advanced lung cancer." Some patients with good performance status showed a "definite survival benefit in addition to palliation." Dr Jeremy George, a Consultant Physician in Thoracic Medicine, believes: "the excitement of PDT lies in its ability to eradicate very early lung cancers which can now be detected by FB. The combination of these two techniques may therefore allow patients exposed to asbestos, with very high risks of malignancy, to be diagnosed and treated in fairly rapid succession."
May 2, 2000
