Hemoptysis, recurrent pneumonia, or a change in the chronic cough in a smoker should be regarded with suspicion. Because of the significant increase in the incidence of lung cancer in women, physicians should keep in mind the diagnosis of lung cancer in the differential diagnosis of women with respiratory problems. Early referral of appropriate cases to a respirologist or thoracic surgeon for diagnostic work-up may allow detection of more cases of localised disease amenable to potentially curative therapy.
The current recommendation against screening for the early detection of lung cancer in high risk populations followed review of four randomised population trials conducted in the United States and Czechoslovakia in the 1970's. Although there were more early, resectable cancers detected, there was no difference in the overall mortality between the screened and control groups. However, these studies have significant limitations. They were performed in men only. The method of sputum cytology examination was suboptimal. There was no long-term un-screened control group and the sample sizes were too small to detect a mortality difference that was less than 50%. Recent case finding pilot studies using newer detection techniques such as improved sputum cytology examination methods, fluorescence bronchoscopy for localisation of small preinvasive bronchial cancers in the central airways, and low-dose spiral CT to detect perihilar lung cancers in high risk populations show promising results. Nevertheless, it must be unequivocally stated that no data from randomised trials of new techniques are available that support implementation of large-scale population screening for lung cancer.
The Lung Tumour Group supports the consensus statement of the International Conference on Prevention and Early Diagnosis of Lung Cancer (Varese, Italy, December 1998) which was co-sponsored by the International Association for the Study of Lung Cancer, Union Internationale Contre de Cancer, and the American Cancer Society that: "Current and former smokers must be advised of their continuing risk of lung cancer. Additional studies are needed to evaluate new technologies in early detection of lung cancer. Organisations and health professionals should support research on new diagnostic techniques, chemoprevention, and develop recommendations regarding how high risk patients can make informed decisions about monitoring the occurrence of lung cancer."
Research relevant to lung cancer screening has been performed at the BC Cancer Agency. Computer assisted image analysis of sputum cells has demonstrated the potential to detect early lung cancer before conventional cytology using malignancy associated changes. Additionally, a Lung Imaging Fluorescence Endoscopic device (LIFE) can detect the presence of pre-invasive lung cancer when ordinary white light bronchoscopy is unremarkable. These developments warrant renewed research into lung cancer screening using this technology generated in the British Columbia Cancer Research Centre combined with spiral CT scans. A demonstration project is currently underway and efforts to fund a larger pilot study have been made.
Patients with bronchial metaplasia or dysplasia detected with these methods are eligible for chemo-prevention treatment trials and enrolled in smoking cessation programs. Surgery is a standard treatment for operable patients with carcinoma in situ. For patients with small early lung cancers who are inoperable due to limited pulmonary capacity and patients with multiple early bronchial cancers, photodynamic therapy is recommended.
Key References:
- Canadian Medical Association: The Canadian task force on the periodic health examination. Can Med Assoc J, 1979;121:1193-1254.
- Shaw GL. Screening for lung cancer. In: Johnson BE, JohnsonDH, eds. Lung Cancer. New York, John Wiley & Sons 1995:55.
- Tucker MA, Murray N, Shaw EG, Ettinger DS, Mabry M, Huber MH, et al. Second primary cancers related to smoking and treatment of small-cell lung cancer. J Natl Cancer Inst 1997;89:1782-8.
- Lam S, MacAulay c, hung J, LeRiche J, Profio AE, Palcic B. Detection of dysplasia and carcinoma in situ with a lung imaging fluorescence endoscope device. J Thoracic Cardiovasc surg 1993;105:1035-40.
- MacAulay C, Lam S, Payne P, LeRiche JC, Palcic B. Malignancy-associated changes in bronchial epithelial cells in biopsy specimens. Anal Quant Cytol histol. 1995;17:55-61.
- Payne PW, Sebo TJ, Doudkine A, Garner D, MacAulay C, Lam S, LeRiche JC, Palcic B. Sputum screening by quantitative microscopy; a re-examination of a portion of the National Cancer Institute Cooperataive Early Lung Cancer Study. Mayo Clin Proc 1997;72:697-704.
- Lam S. Bronchoscopic, photodynamic, and laser diagnosis and therapy of lung neoplasms. Curr Opin Pulm Med 1996;2:271-276.