A preliminary investigation into textural features of intratumoral metabolic heterogeneity in (18)F-FDG PET for overall survival prognosis in patients with bulky cervical cancer treated with definitive concurrent chemoradiotherapy

Abstract

We examined the role of intratumoral metabolic heterogeneity on (18)F-FDG PET during concurrent chemoradiotherapy (CCRT) in predicting survival outcomes for patients with cervical cancer. This prospective study consisted of 44 patients with bulky (≥ 4 cm) cervical cancer treated with CCRT. All patients underwent serial (18)F-FDG PET studies. Primary cervical tumor standardized uptake values, metabolic tumor volume, and total lesion glycolysis (TLG) were measured in pretreatment and intra-treatment (2 weeks) PET scans. Regional textural features were analyzed using the grey level run length encoding method (GLRLM) and grey-level size zone matrix. Associations between PET parameters and overall survival (OS) were tested by Kaplan-Meier analysis and Cox regression model. In univariate analysis, pretreatment grey-level nonuniformity (GLNU) > 48 by GLRLM textural analysis and intra-treatment decline of run length nonuniformity < 55% and the decline of TLG (∆TLG) < 60% were associated with significantly worse OS. In multivariate analysis, only ∆TLG was significant (P = 0.009). Combining pretreatment with intra-treatment factors, we defined the patients with a initial GLNU > 48 and a ∆TLG ≤ 60% as the high-risk group and the other patients as the low-risk. The 5-year OS rate for the high-risk group was significantly worse than that for the low-risk group (42% vs. 81%, respectively, P = 0.001). The heterogeneity of intratumoral FDG distribution and the early temporal change in TLG may be an important predictor for OS in patients with bulky cervical cancer. This gives the opportunity to adjust individualized regimens early in the treatment course.

Keywords: 18F-FDG PET; Cervical cancer; chemoradiotherapy; texture analysis.

Figure 1

Kaplan-Meier estimates of overall survival according to the textural feature gray-level nonuniformity (GLNU) extracted from pretreatment ¹⁸F-FDG PET in study cohort (n = 44) (A). Kaplan-Meier estimates of overall survival according to the change of total lesion glycolysis (ΔTLG) based on 2nd-week ¹⁸F-FDG PET in patients with low GLNU (n = 26) (B) and high GLNU (n = 18) (C). In the high GLNU group, patients with poor treatment response (lesser ∆TLG decline) had significantly worse survival outcomes.

Figure 2

Flow diagram of two-step risk-stratification strategy based on pretreatment and intra-treatment PET imaging parameters (A). Kaplan-Meier estimates of progression-free survival (B) and overall survival (C) according to the risk group of patients.