Screening with low-dose computed tomography (CT) intended as an early-detection test had no effect on outcomes for patients with small cell lung cancer, according to a study published in CHEST.
Previous studies with a limited number of participants have reported conflicting results regarding whether low-dose CT screening can detect an earlier stage of small cell lung cancer and therefore impart a survival benefit to patients. In the current study, investigators examined data related to low-dose CT screenings from the National Lung Screening Trial. In this randomized trial, small cell lung cancer was classified as screen-detected if diagnosis was given ≤1 year after a positive screen or after a longer time with ≤1-year time gap between diagnostic procedures; non-screen detected if the participant was diagnosed without receiving CT scans; and interval-detected if diagnosis was given ≤1 year after a negative screen. Positive screens were not always for cancer.
Of the 143 cases of small cell lung cancer diagnosed, 34.2% (n=49) were screen-detected, 55.2% (n=79) were non-screen detected, and 10.5% (n=15) were interval-detected. Of the screen-detected and interval-detected participants, a higher proportion of small lung cell cancer vs non-small lung cell cancer was interval-detected (23% vs 5%, P <.0001), and more small lung cell cancers vs non-small lung cell cancers were advanced stage cancer (86% vs 36% stage 3/4, P <.0001). This was seen across all 3 detection groups: small cell lung cancer was stage 3/4 in 80% screen-detected, 86% interval-detected, and 90% of non-screened cancers. A large proportion of even the very small nodules detected by low-dose CT were late stage, and the results showed no difference in survival rates between screen-detected, interval-detected, or no-screen detected small cell lung cancers.
Study investigators concluded that while yearly low-dose computed tomography screens did detect a significant number of small cell lung cancer cases, this had no significant effect on outcomes. “Our results suggest that for a screening modality to be successful in reducing SCLC [small cell lung cancer] mortality, SCLC should be detectable earlier than it is with [low-dose] CT.”
Thomas A, Pattanayak P, Szabo E, Pinsky P. Characteristics and outcomes of small cell lung cancer detected by CT screening [published online August 3, 2018]. CHEST. doi:10.1016/j.chest.2018.07.029