Background: In patients with non-small cell lung cancer (NSCLC), previous studies have shown a prognostic benefit of maximum standardized uptake (SUV max) values on positron emission tomography (PET). Because tumor size is also prognostic and is associated with SUVmax, we sought to better characterize their relationship. We hypothesize that the ratio of SUVmax to tumor size is a clinically useful measurement. Methods: A retrospective review was performed for patients (tumors ≥ 1 cm) undergoing resection of NSCLC. Patients were placed into quartiles (SUVmax and SUVmax to tumor size ratio) and compared for clinical and pathologic factors. Predictors of SUVmax and SUVmax to tumor size ratio on survival were evaluated. Results: Among 530 patients, increasing tumor size (odds ratio [OR], 2.04; confidence interval [CI], 1.68-2.47; p < 0.001) was an independent predictor of higher SUVmax. Patients in quartiles by the ratio of SUVmax to tumor size demonstrated no significant difference in median tumor size. Those patients with the highest ratios (QR4, 3.21-27.5) more frequently had poorly differentiated tumors (51%; p < 0.001), were likely to have lymph node metastases (30%; p < 0.001), and had poor 3-year disease-free survival (DFS) (58%; p = 0.013). On multivariate analysis, as a continuous variable SUVmax to tumor size ratio was a stronger independent predictor of survival than SUVmax alone (hazard ratio [HR], 1.06; CI, 1.00-1.13 versus HR, 1.02; CI, 0.99-1.06). Using cutpoint analysis, a high SUVmax to tumor size ratio was also a stronger predictor of survival than was high SUVmax alone, particularly for tumors 1-3 cm (HR, 1.53; CI, 0.93-2.53 versus HR, 1.15; CI, 0.69-1.93). Conclusions: The ratio of SUVmax to tumor size may be a more important indicator of prognosis than SUVmax alone in patients with NSCLC. In particular, the use of the ratio may be appropriate for identifying patients with small tumors who are at high risk for lymph node metastases and poor survival.
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Cardiology and Cardiovascular Medicine