Increased Standardized Uptake Value in the Primary Lesion Predicts Nodal or Distant Metastases at Presentation in Lung Cancer

Standardized uptake value (SUV) has been linked to tumor aggressiveness and long-term prognosis. Based on the hypothesis that positron emission tomography (PET) SUV serves as a surrogate for biologic aggression, we investigated whether SUV in the primary lesion, independent of size, correlates with the presence of nodal or distant metastases at the time of presentation. We retrospectively reviewed computed tomography (CT) scan, PET scan, and histologic findings of consecutive patients in our lung cancer referral population evaluated between December 15, 2000 and April 15, 2004. Only patients with primary non-small-cell lung cancer and pathologic confirmation of nodal status or conventionally accepted non-PET proof of distant metastases were included for analysis. One hundred thirty-nine patients had complete results, including CT, PET, and independent confirmation of nodal or distant disease. The stage distribution was as follows: 33 IA, 24 IB, 5 IIA, 9 IIB, 21 IIIA, 8 IIIB, and 39 IV. Simple logistic regression analysis demonstrated a highly significant correlation between SUV of the primary lesion and the presence of nodal or distant metastases at the time of presentation (P = 0.0036). When odds ratios were calculated, a 13% increase in the likelihood of nodal/ distant disease was found for every unit increase in SUV. We conclude that PET SUV, independent of size, is a marker of biologic aggression. Elevated SUV in the primary lesion at presentation should prompt high suspicion and mandates meticulous search for nodal or distant disease.