title: Ratio of positron emission tomography uptake to tumor size in surgically resected non-small cell lung cancer.
abstract: 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 SUV(max), we sought to better characterize their relationship. We hypothesize that the ratio of SUV(max) 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 (SUV(max) and SUV(max) to tumor size ratio) and compared for clinical and pathologic factors. Predictors of SUV(max) and SUV(max) 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 SUV(max). Patients in quartiles by the ratio of SUV(max) 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 SUV(max) to tumor size ratio was a stronger independent predictor of survival than SUV(max) 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 SUV(max) to tumor size ratio was also a stronger predictor of survival than was high SUV(max) 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 SUV(max) to tumor size may be a more important indicator of prognosis than SUV(max) 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.
authors.affiliation: Division of Thoracic Surgery, New York Presbyterian Hospital, Weill Cornell Medical College, New York, New York 10021, USA. brs9035@med.cornell.edu
authors.forename: Brendon M
authors.initials: BM
authors.lastname: Stiles
authors.forename: Abu
authors.initials: A
authors.lastname: Nasar
authors.forename: Farooq
authors.initials: F
authors.lastname: Mirza
authors.forename: Subroto
authors.initials: S
authors.lastname: Paul
authors.forename: Paul C
authors.initials: PC
authors.lastname: Lee
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Port
authors.forename: Timothy E
authors.initials: TE
authors.lastname: McGraw
authors.forename: Nasser K
authors.initials: NK
authors.lastname: Altorki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D049268:Positron-Emission Tomography; D012189:Retrospective Studies