A review of detection methods for the early diagnosis of lung cancer.

Abstract The purpose of this review has been to examine the value of periodic screening of a non-hospitalized population by reconciling the divergent viewpoints and results reported in the literature. To this end, highlights in the history of detection methods for the discovery of lung cancer have been reviewed. Reports of studies of pulmonary cytology have been examined in the light of its potential for the early detection of lung cancer. Literature on detection of lung cancer by radiographic means has been reviewed in terms of its potential for discovering ‘early’, small or asymptomatic lesions in cases of lung cancer. Other methods for the early detection of lung cancer have been discussed. Evidence on the degree of success of cytologic and radiographic methods in detecting early lung cancer has been discussed. There are several examples in the literature of cytologic diagnosis of lung cancer in the absence of radiographic findings; these are usually central lesions. In some cases in situ lesions have been recognized cytologically. Radiographic detection of lung cancer in an asymptomatic stage is most effective in peripheral lesions where the cytologic method has a lower yield. In this respect there is a tendency for these two major techniques to serve complementary functions. X-raying a population and reading films is faster and cheaper than collecting sputum, preparing and reading slides. However, without sacrificing sensitivity the cytologic suspect category has considerably greater specificity than the radiographic method. Resectability has repeatedly been shown to be approximately twice as great among those lung cancer cases discovered by routine radiographic surveys as among those found after the appearance of symptoms. Among those adequately followed up, the survival rate of these asymptomatic cases has been increased. Evidence in the literature for better survival rates after cytologic detection is suggestive but has not been satisfactorily documented. While both cytologic and radiographic methods have often been instrumental in prolonging or saving lives by making it possible to recognize the existence of and treat unsuspected lung cancer, the decision to use either or both of these techniques on a routine basis ultimately rests on economic factors. Assuming a limited supply of funds, the public health is best served by those measures accomplishing the most per dollar in terms of lowered morbidity and mortality. Whatever evidence is available on net cost per case of lung cancer, case-finding programs must be weighed against similar information on other causes of death and morbidity. Although the time may not now be ripe for widespread use of screening programs to find curable lung cancer, the door has been opened for urgently needed pilot studies in which cytologic detection, diagnosis and rapid follow-up with definitive treatment are coordinated . Without making prompt treatment a part of the study plan, the information on potential survivorship will fall short of the goal. Such studies can also contribute to basic knowledge of the pathogenesis of lung cancer. Short of mass periodic screening of the entire adult population, it would behoove male cigarette smokers over the age of 40, as a minimum, to obtain a cytologic examination of sputum and chest X-rays at alternate 6-month intervals and both cytologic and radiographic check-ups semi-annually if respiratory symptoms are present. In doing so, an individual might reasonably expect a statistically greater chance of survival if a lesion were found than would be the case if he waited for clear evidence of being ill. Other tests which might be fruitfully carried out at the same examination are beyond the scope of this review.