[Primary tumor SUVmax measured on (18)F-FDG PET-CT correlates with histologic grade and pathologic stage in non-small cell lung cancer].

OBJECTIVE

To assess the relationship between preoperative maximum standardized uptake value (SUVmax) measured on (18)F-FDG PET-CT and clinicopathologic parameters in patients with surgically resected non-small cell lung cancer (NSCLC).

METHODS

A total of 540 patients (348 men and 192 women, mean age 60 ± 10 years) with histologically proven non-small cell lung cancer, who had undergone both preoperative (18)F-FDG PET-CT imaging and curative surgery in our institution from October 2006 to January 2013, were analyzed retrospectively in this study. Primary tumor (18)F-FDG uptake, measured as SUVmax corrected for lean body mass, was compared among different variables and correlated with tumor size, histologic grade and postoperative pathologic TNM stage. Histologic grade was categorized into three degrees, where grade I represents highly, grade II moderately and grade III poorly differentiated. Large cell carcinomas were all assessed as poorly differentiated (grade III). Pathologic stage was assigned according to the seventh AJCC TNM staging system.

RESULTS

There were 344 adenocarcinomas (AC, non- BAC type), 146 squamous cell carcinomas (SCC), 28 bronchioloalveolar carcinomas (BAC), 10 adenosquamous carcinomas (ASC) and 12 other type carcinomas (OTC, including 6 large cell carcinomas, 5 sarcomatoid carcinomas and 1 lymphoepitheloid carcinoma); the SUVmax in ascending order was BAC (1.3 ± 1.1), AC (5.1 ± 3.4), ASC (8.5 ± 2.8), SCC (9.9 ± 4.6) and OTC (10.9 ± 5.1), respectively. There were 76 grade I, 251 grade II and 213 grade III; the SUVmax in ascending order was grade I (2.4 ± 2.2), grade II(5.9 ± 3.9), grade III (8.4 ± 4.4), respectively, and significant difference was identified among grade I, grade II and grade III (all P < 0.01). The SUV max was positively correlated with tumor size (r = 0.564, P < 0.01), histologic grade (r = 0.492, P < 0.01), T stage (r = 0.306, P < 0.01), N stage (r = 0.368, P < 0.01), and TNM stage (r = 0.437, P < 0.01).

CONCLUSIONS

The preoperative SUV max of the primary tumor differed significantly among histologic types in NSCLC. There were positive correlations between SUV max and tumor size, histologic grade and pathologic stage. Our findings may suggest that a high SUVmax could be used to identify a high-risk population who would benefit most from adjuvant therapies.