To examine the association between 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) and prognosis in patients with clinical stage Ia non-small cell lung cancer (NSCLC) who had surgical resection with curative intent.
We retrospectively reviewed data collection forms and VA administrative records of 75 veterans with resected stage Ia NSCLC who were enrolled in a prospective study of PET imaging from 1999 to 2003. We used Cox proportional hazards analysis to examine the association between FDG uptake and survival four years from enrollment.
Most patients were men (97%) and the mean age was 67±9 years. Almost half of the patients (44%) had adenocarcinomas and 35% underwent a sub-lobar resection. The mean maximum standardized uptake value (SUVmax) was 4.9±2.5 in survivors and 7.1±3.9 in non-survivors (p=0.045). Before and after adjustment for age, tumor size, histology and type of resection, the hazard of death was significantly higher in patients with squamous cell histology (adjusted HR 4.6, 95% CI 1.09 to 18.9) and those with higher degrees of FDG uptake (adjusted HR 1.21 per 1 unit increment, 95% CI 1.01 to 1.45). At a threshold value of 5 for SUVmax, 34 of 39 patients (87%) with low FDG uptake survived, compared to only 24 of 36 patients (67%) with high FDG uptake (p=0.04). Qualitative measurement of FDG uptake was not associated with outcome and correlated poorly with quantitative measures (r2=0.11).
High FDG uptake as measured by SUVmax identifies individuals with stage Ia NSCLC who are at increased risk of death following surgical resection. Such high risk patients may be good candidates for participation in future trials of adjuvant therapy.
Adjuvant chemotherapy is currently the standard of care for stage II NSCLC and may be beneficial in stage Ib NSCLC. A recent meta-analysis showed a significant trend towards harm when adjuvant therapy was administered in stage Ia NSCLC, however, our results suggest certain patients with stage Ia NSCLC may benefit from adjuvant therapy after resection.
Viswam Nair, No Financial Disclosure Information; No Product/Research Disclosure Information