Carcinoma of the lung

Carcinoma of the lung is one of the most frequently diagnosed tumours world-wide, and is the commonest fatal malignancy in industrialized countries [1,2]. In the United Kingdom in 1985 there were approximately 40 500 cases [3], and in the United States in 1989 there were 155 000 [4]. At one time the predominant histological type was squamous carcinoma, but in recent years, at least in North America, this has been outstripped by adenocarcinoma [5]. Prognosis is poor. Resection is the treatment of choice for non-small cell carcinoma, but only 40% of patients, at the most, present with an operable turnout, and, of these, only one-quarter are alive and cured at 5 years [6]. The outlook for patients with small cell carcinoma is even gloomier; although the initial response to chemotherapy is excellent, the tumour recurs in a matter of weeks or months, and 5-year survival is somewhere between 2% and 3%. Most of the long term survivors will have had 'limited' or even resectable disease at presentation [7-91. The pathology of lung cancer, at least in the United Kingdom, is neglected. Most pathologists find the study of lymphomas more rewarding. In teaching centres lung cancer research seems to be given a low priority, either because of its apparently hopeless prognosis or because it is seen to be 'self-inflicted'. In the Journal of Pathology (a research orientated, mainly histopathological publication), of the 138 peer reviewed papers in 1993, only three dealt with lung cancer. During the same period, there were 18 dealing with lymphomas. Despite the apparent lack of interest, there have been significant advances in recent years. The purpose of this review is to give an account of these advances, and to examine their impact on routine day to day laboratory diagnosis.