Approximately 150,000 Americans will die this year from bronchogenic carcinoma.
There are no immediate hopes that advances in surgical, radiotherapeutic, chemotherapeutic or biological therapies will make any significant reduction in this carnage.
Reduction in mortality secondary to prevention of initiation of smoking in children and cessation of smoking are salutory, but any benefits will not be realized for a number of decades.
The only hope for any short term reduction in mortality from lung cancer lies in early detection.
The five year survival of approximately 12% in series of patients with lung cancer occurs with depressing regularity in statistics from local hospitals, regional and national statistics in this country and in other nations.
Three large U.S. prospective studies have documented 5 year survivals of 32-35% in patients enrolled in programs designed to screen for lung cancer.
Despite this very strong suggestive data, a number of large and influential organizations have endorsed an official position that screening for lung cancer is ineffective and not to be recommended. The official position is that, in order to prove effectiveness of screening, a statistically significant reduction in mortality in the entire population screened must be shown in a prospective randomized trial. Historically, this requirement was not met before screening recommendations regarding cervical cancer and breast cancer were implemented.
Major controversy continues to involve the interpretation of the results of the largest controlled study of lung cancer in the U.S., the Mayo Lung Project. In this study, approximately 10,000 patients were enrolled in each arm of a prospective randomized study. The control group was given only advice to obtain a yearly chest roentgenogram. The study group recieved chest roentgenograms and sputum cytology examinations every four months during the duration of the study. The five year survival for patients with lung cancer was 40% versus 15% in favor of the screened group, despite that fact that the "advice" group was "contaminated" in that approximately 50% of patients had at least one screening CXR during the study.
Despite this striking improvement in survival the population mortality in the two groups was not different. This was because there were more cases of lung cancer discovered in the screened group. The explanation given was that various biases had produced the apparent benefit in favor of screening. These biases include lead time bias (cancers are picked up early but they are still going to die, they just die later), length bias and overdiagnosis bias (these are not "real" lung cancers and the patient probably wouldn't have died even if no treatment had been given).
To the clinician with significant experience with lung cancer, these explanations ring hollow. The attribution of overdiagnosis bias seems particularly absurd. Significant new data from our colleagues in Japan provides further proof of the effectiveness of mass screening in reduction of lung cancer mortality and addresses the issue of the various types of bias.
A prospective study in Japan is not possible because mass screening is a reality there. National laws mandate access to yearly chest roentgenograms in the workplace, and screening programs are also available in schools and regional health clinics. Data on over 3 million patients screened since 1987 has been carefully examined by the Japanese National Lung Cancer Screening Research Group and published in a number of papers.
This data confirms the improved 5 year survival (32-56%) in screened patients seen in the National Cancer Institute study in the U.S. and provides strong evidence against the attribution of overdiagnosis and lead time bias.
A definitive study is necessary to solve once and for all the effectiveness of mass screening for lung cancer, but in the meantime, the preponderance of evidence is clearly in favor of screening. We should delay no longer.
If our representative national professional and governmental agencies are unwilling to advocate screening, then it is up to the initiative of individual practitioners to do so - now.
"Until and unless, significant improvements are made in the therapy of advanced-stage lung cancer, the decision not to screen is tantamount to the decision not to treat for cure."John McDougal MD
