In 1991, a group of physicians from Cornell University Medical Center (now Weill Medical College of Cornell University) started discussions with specialists from other institutions to find a common research goal. They found this goal in early lung cancer detection, and the promise offered by helical CT imaging. In 1992, ELCAP (Early Lung Cancer Action Program) was born. It was designed to determine the difference in proportion of early stage disease between two methods of early diagnosis (chest radiography and low-dose CT) as measured by the increase in the proportion of Stage I diagnoses following a well-defined regimen of screening. This regimen of screening recommended and defined the further workup of findings on the CT scan before the subsequent round of screening. The regimen is critical as it embodies the concept that screening is a clinical diagnostic process, not simply a standalone test. The ELCAP methodology can provide the relevant diagnostic information to any desired precision from two rounds of screening – the baseline round and one single repeat annual round, by enrolling a sufficient number of individuals in the required 2 years of screening. Ultimately, the design provided for the determination of the cure rate of lung cancer which could be achieved under screening as compared to that under usual care. Under screening is a specific term which refers to the diagnoses of lung cancer made solely while participants are undergoing any given round of screening (both screen-diagnosed and interim-diagnosed cases).
The ELCAP investigators at Weill Cornell Medical College invited the investigators at New York University Medical Center to participate in the study. Together they screened 1,000 high-risk, asymptomatic participants and found that over 80% of the lung cancer diagnoses were of clinical Stage I. The diagnostic results of ELCAP were published in 1999 in the Lancet which stimulated research efforts on CT screening for lung cancer throughout the world. It led to another screening research study at 12 institutions in New York State called the NY-ELCAP which replicated the ELCAP results. Simultaneously, in 1999, ELCAP started to host international conferences which led to the development of a protocol which allowed for international collaboration and data pooling throughout the world.
Since then, in depth discussions of topical screening research questions have been held at the twice yearly International Conferences on Screening for Lung Cancer. By pooling the data collected under this protocol from many national and international institutions, I-ELCAP was able to show, in several 2006 publications that 1) lung cancers diagnosed under screening were typically small, including small-cell cell carcinomas, and 2) the estimated cure rate of patients whose lung cancer was diagnosed under screening. After long-term follow-up of 31,456 asymptomatic participants, 484 of whom had lung cancer diagnosed under CT screening of which 414 (86%) had clinical Stage I disease, the estimated overall cure rate for the 484 patients diagnosed under CT screening was 80% (95% CI: 74% – 85%). With these and other publications, I-ELCAP has remained at the forefront of screening research often the first to call attention to important new topics which have then been studied by many others. Such topics included, among many others, nodule growth rate assessment, identification of different types of nodules (solid, part-solid, and nonsolid) and their differing pathologic findings and survival rates, identification of emphysema, coronary artery calcifications, mediastinal masses, the importance of including smoking cessation into the screening program.
Numerous publications document the findings of the I-ELCAP members’ work. Among these findings as already stated above:
Curability of Stage I lung cancers is 80-90%
Cost of CT screening for lung cancer compare favorably with breast, cervical, and colon cancer screenings