Spiral CT Screening Can Detect Lung Cancer Early
Early Lung Cancer Detection
"The findings reported by the I-ELCAP are encouraging and add to the knowledge base that is building related to the value of screening for lung cancer. This is a solid, well established program that has a long track record of international leadership in developing the algorithms for screening and the management of small lung lesions detected on CT.
The study shows that use of a powerful imaging tool, i.e., spiral CT, finds lung cancers when they are very small, and when prognosis is measurably better than when tumors are larger and advanced. The findings reported here are from multiple institutions, providing confidence that their model can duplicated in other settings, and the authors have shown that concerns about excessive false positive rates can be addressed by adherence to protocols for measuring lesion size and growth as a criteria for biopsy. Positivity rates are quite modest, and the predictive value at time of biopsy is quite high.
The authors also show that survival is more favorable when treatment is initiated rapidly after diagnosis (the literature shows that even small delays in treating lung cancer can adversely affect the survival rate). With respect to the question of whether the cancers they are finding are truly life threatening, all patients who had treatable lung cancers and refused treatment have died. The excellent survival of those with small cancers isn't countered by poor survival of similar size cancers. If this is the pattern of survival for screen detected lung cancers, that is very good news.
"Still, the study has some limitations. Because it is an observational study of volunteers (this population is not randomized), we don't know much about who they are, i.e., how representative are they of the high risk population that we might recommend for regular screening? If they are healthier on average, then these results could be more favorable than we ultimately would expect if screening were to be recommended to all adults with a significant smoking history. Still, it's highly unlikely that this completely invalidates the observation of a favorable benefit from early diagnosis. There are also unanswered questions about some other aspects of the study: We don't really know much about the period of observation beyond a baseline and repeat screening; how many people had more than two exams, for example -