Increases in NSCLC survival 'an artefact of PET assessment'

By Liam Davenport

There has been no increase in survival among non-small-cell lung cancer (NSCLC) patients in recent years, with evidence suggesting otherwise likely due to positron emission tomography (PET)-induced stage migration and selection bias, say US scientists.

PET is a more sensitive method of detecting the extent of NSCLC than conventional staging technologies, and its usage in the USA has increased rapidly since being approved by Medicare for NSCLC patients in 1998.

However, the sensitivity of PET results in the assignment of higher tumor stages than would otherwise have been given, and the resultant stage migration may appear to improve stage-specific survival without any actual patient benefit.

To investigate further, Kevin Schulman, from Duke Clinical Research Institute, in Durham, North Carolina, and colleagues reviewed Medicare-linked data from the Surveillance, Epidemiology, and End Results database for changes in overall survival, stage-specific survival, and stage distribution in 97,007 Medicare beneficiaries with NSCLC treated between 1998 and 2003.

The proportion of patients who received at least one PET scan increased during the study period from 5% to 48%. This was accompanied by an increase in the proportion of patients with stage IV disease and a decrease in the proportion of patients with unstated disease.

By 2003, consistent with guidelines recommendations, 64% of early-stage disease patients had received a PET scan within 4 months of diagnosis, compared with 40% of those with late-stage disease.

Overall survival remained constant during the study period, at 33.7% in 1998-99 and 33.6% in 2002-03, the team reports in the Journal of Clinical Oncology. Stage-specific survival remained unchanged or improved, with a significant increase in 2-year survival among patients with advanced-stage disease, from 12% to 15%. The results were unaffected by sensitivity analyses.

"Previous reports of an association between PET use and increased survival among patients with NSCLC during this period may be attributable to a combination of stage migration and preferential administration of PET to patients with less advanced disease," the team concludes.

"The ability of PET to affect patient management, healthcare resource use, and costs remains an important area of research that may change as new treatments become available."

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