The relationship between the tumor FDG uptake, metastatic potential, and the FIGO stage in patients with uterine cervical cancer

Objectives: We retrospectively evaluated the relationships between the primary tumor ¹⁸F-fluorodeoxyglucose (FDG) uptake measured as the maximum standardized uptake value (SUVmax), SUVpeak, metabolic tumor volume (MTV), total lesion glycolysis (TLG), tumor size, and pelvic lymph node metastasis, paraaortic lymph node metastasis, distant metastasis, and the FIGO stage in patients with uterine cervical cancer on pretreatment FDG positron emission tomography/computed tomography (PET/CT).

Methods: The study population included 42 patients (mean age, 62.48 years; range, 34-88 years) with uterine cervical cancer who underwent FDG PET/CT for staging before treatment. The SUVmax, SUVpeak, MTV, TLG, and tumor size of the primary tumor were calculated. The pathological subtypes of the uterine cervical cancers consisted of 35 squamous cell carcinomas, and 7 adenocarcinomas. The patients were divided into low and high SUVmax groups based on the median primary tumor SUVmax. The low SUV group consisted of 21 patients with SUVmax <15.67, the high SUV group consisted of 21 patients with SUVmax ≥15.67. The patients were also divided into two groups according to the median SUVpeak, MTV, TLG, and tumor size. Their data were compared using Fisher’s exact test. Spearman’s rank correlation coefficient was used to evaluate the correlations. P values of < 0.05 were considered to indicate statistical significance. The parameters were expressed as the mean ± standard deviation. Results: The SUVmax, SUVpeak, MTV, TLG, and tumor size of the primary tumors of patients with uterine cervical cancer were 16.54 ± 6.80, 12.95 ± 5.55, 69.72 ± 53.86, 518.58 ± 512.50, and 4.99 ± 1.75, respectively. No significant differences were observed between squamous cell carcinoma and adenocarcinoma in SUVmax (p=0.448), SUVpeak (p=0.509), MTV (p=0.717), TLG (p=0.698), or tumor size (p=0.816). The high SUVmax group (≥15.67) had a significantly higher FIGO stage (I/II vs. III/IV, p=0.004) than the low SUVmax group (<15.67). The high SUVpeak group (≥12.56) also had a significantly higher FIGO stage (I/II vs. III/IV, p=0.025) than the low SUVpeak group (<12.56). In addition, there were low to moderate positive correlations between the MTV and the FIGO stage, the TLG and the FIGO stage, and the tumor size and the FIGO stage (r=0.385, 0.393, 0.447, and p=0.012, 0.010, 0.003, respectively). The differences in pelvic lymph node metastasis, paraaortic lymph node metastasis, and distant metastasis were not statistically significant (P>0.05). Conclusion: The larger the size of the tumor in patients with uterine cervical cancer, the higher the FIGO stage. In the same way, the higher the tumor uptake (SUVmax, SUVpeak, MTV, TLG), the higher the FIGO stage tended to be. The tumor uptake (SUVmax, SUVpeak, MTV, TLG) can also be regarded as an index for analogizing the FIGO stage.