PET/CT in gynecologic cancer: present applications and future prospects--a clinician's perspective

The role of 18F-FDG PET/CT-based quantitative metabolic parameters in patients with ovarian clear cell carcinoma

BACKGROUND

Ovarian clear cell carcinoma (CCC) is enriched in genes associated with glucose metabolism.

OBJECTIVE

To evaluate the 18F-FDG PET/CT-based metabolic variables and the correlations with clinicopathologic features in OCCC patients.

METHODS

We measured quantitative parameters including maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG).

RESULTS

A total of 22 patients were included. PET/CT-based metabolic parameters were calculated for 20 patients because two had low glucose-uptake tumor. The median SUVmax was 7.25 (range 2.50-14.80). Spearman's correlation test revealed that the level of pre-operative serum cancer antigen 125 (CA 125) correlated significantly with MTV (P= 0.020) and TLG (P= 0.023). Interestingly, platinum-sensitive patients tended to have higher MTV/TLG though significance not achieved. On univariate analysis, the following four variables (stage, residual disease, platinum sensitivity and MTV50) were significant for both progression-free survival and overall survival. Besides, four metabolic parameters (MTV40, TLG40, TLG50 and TLG60) were significantly associated with patients' overall survival. Out of expectation, ovarian CCC patients with higher level of MTV/TLG tended to have better survival.

CONCLUSIONS

18F-FDG PET/CT-based metabolic volumetric parameters might be predicators for survival in ovarian CCC patients. Cautions should be taken when interpreting the results due to the small sample size.

Prognostic value of metabolic tumor volume and total lesion glycolysis assessed by 18F-FDG PET/CT in endometrial cancer

OBJECTIVE

Surgical staging is the most confidential method for prognosis prediction. However, in which stage the surgery is needed and the treatment management of these patients is controversial. Presentation of new determinant factors with imaging methods for prediction of poor prognosis can provide better disease management. The aim of our study was to demonstrate the ability of metabolic tumor volume and total lesion glycolysis as a prognostic factor to predict the disease-free survival time, necessity of adjuvant radiotherapy-chemotherapy, and the association of these parameters with the clinicopathological features.

METHODS

Forty-four endometrial cancer diagnosed patients whose PET/CT scans were performed for treatment planning were included in our study. Metabolic parameters (SUVmax, metabolic tumor volume, total lesion glycolysis) of the primary tumor were calculated. Abdominal hysterectomy was performed for all patients. Histopathologic findings were noted. Patients were followed for 31.4 ± 14.8 months.

RESULTS

Metabolic tumor volume and total lesion glycolysis were significant prognostic factors for disease-free survival, whereas SUVmax did not effect disease-free survival. According to regression analysis, only metabolic tumor volume was found significant for radiotherapy planning (cutoff metabolic tumor volume; 26.30 ml). There was significant association between metabolic tumor volume, total lesion glycolysis and early-stage, myometrial invasion, and lymph node positivity. We observed only weak association between SUVmax and myometrial invasion. ROC curve calculated metabolic tumor volume and total lesion glycolysis cutoff values as 19.6 ml and 90 g for early-stage, 14.3 ml and 173.4 g for myometrial invasion, and 29.7 ml and 283.1 g for lymph node positivity, respectively.

CONCLUSION

Metabolic tumor volume and total lesion glycolysis may be used as prognostic factors for endometrial cancer. The association between SUVmax and clinical findings, disease-free survival, histopathological features are weak. Further studies are needed for demonstrating the prognostic value of metabolic volumetric parameters.

A novel preoperative scoring system based on 18-FDG PET-CT for predicting lymph node metastases in patients with high-risk endometrial cancer

The purpose of this study was to develop a model predicting the probability of pelvic-paraaortic node metastases in high-risk endometrial cancer patients. This trial included 41 high-risk endometrial cancer patients. All of the patients underwent an 18-FDG PET-CT followed by surgical staging, including a pelvic and paraaortic lymphadenectomy. We developed a useful scoring system combining weighted risk factors derived from a regression model: (3 × presence PET-CT involvement) + (3 × PET-CT maximum standardised uptake value ≥20) + (2 × diabetes comorbidity) + (1 × age ≥60 years) + (1 × body mass index ≥30). The area under the curve of the resulting score was 0.848. There was 75% sensitivity, 89% specificity and a 75% positive predictive value and 89% negative predictive value when a score of 6 was used as the cut-off. Our novel preoperative scoring system is an accurate method for the preoperative evaluation of lymph node metastases, and thus will aid gynaecological oncologists in selecting EC patients who may benefit from a lymphadenectomy. Impact statement What is already known on this subject? Endometrial cancer (EC) is a common gynaecological malignancy. Surgical staging is currently the standard treatment and the gold standard for evaluating lymph node metastases (LNm) is a surgical assessment (Chan et al. 2006 ). Three previous randomised clinical studies failed to find a clear therapeutic role for the lymphadenectomy; thus, the utility of this surgical procedure in high-risk early-stage EC remains under debate (Benedetti Panici et al. 2008 ; Kitchener et al. 2009 ; Signorelli et al. 2015 ). Non-invasive techniques that accurately identify lymph node metastases would reduce costs and complications. What do the results of this study add? Our developed novel scoring system that is based on positron emission tomography-computer tomography (PET-CT) with 2-deoxy-2-(18F) flouro-2-D-glucose (FDG) may facilitate the identification of patients at an increased risk of LNm. What are the implications of these finding for clinical practice and/or further research? This study shows that our novel preoperative scoring system provides an accurate method for the preoperative evaluation of LNm, and thus could guide gynaecologic oncologists in selecting the high-risk endometrial cancer patients who may benefit from a systematic lymphadenectomy. Further larger, prospective studies are needed to confirm the accuracy and the feasibility of our scoring system.

Normal Variants and Pitfalls Encountered in PET Assessment of Gynecologic Malignancies

Combined PET/computed tomography is used for oncological indications. PET/computed tomography benefits from the metabolic information of PET and the anatomic localization of computed tomography. The integrated scanner provides data with accurate registration of anatomy and molecular information. Many physiologic conditions, normal variants, and benign lesions within the pelvis and the body can cause confusion and uncertainty. False-negative results owing to low ¹⁸F-fluorodeoxyglucose uptake from the tumor can produce diagnostic challenges and inaccurate conclusions. This article reviews normal variants and potential pitfalls encountered in PET assessment of gynecologic malignancies to provide useful information for the referring and reporting physicians.

FDG PET-CT of gynecologic cancers: pearls and pitfalls

FDG PET-CT plays an important role in treatment planning and in prognosis assessment of gynecologic cancer patients. Detection of hypermetabolic tissue with FDG PET, when combined with the high spatial resolution of CT, results in improved cancer detection and localization not afforded by either modality independently. This article is a primer for a radiologist performing PET-CT on gynecologic cancer patients and includes the imaging protocol, normal pattern of FDG distribution in the female pelvis and the lymph node drainage pathways from the gynecologic organs. Clinically relevant imaging findings that should be included in the report are discussed. Case examples illustrate how potential errors in exam interpretation can be avoided by concurrently performing a high-quality diagnostic CT with the FDG PET scan and by analyzing both the stand-alone and the fusion images.

High Diagnostic Value of 18F-FDG PET/CT in Endometrial Cancer: Systematic Review and Meta-Analysis of the Literature

The aim of this study was to evaluate the diagnostic performance of (18)F-FDG PET/CT for the preoperative assessment of lymph node metastases (LNM) in endometrial cancer patients and for the assessment of endometrial cancer recurrence (ECR) after primary surgical treatment.

METHODS

A comprehensive search was performed on Pubmed/MEDLINE databases for studies reporting the diagnostic performance of (18)F-FDG PET/CT for assessment of LNM and ECR published up to August 15, 2015. Twenty-one studies (13 for LNM and 8 for ECR) were included in the systematic review and meta-analysis. Pooled estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of the (18)F-FDG PET/CT were calculated along with 95% confidence intervals (CIs). A summary receiver-operating-characteristics curve (SROC) was constructed, and the area under the SROC curve (AUC) was determined along with Q* index.

RESULTS

The overall pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and AUC (with 95% CI) of (18)F-FDG PET/CT for detection of LNM were 0.72 (95% CI, 0.63-0.80), 0.94 (95% CI, 0.93-0.96), 10.9 (95% CI, 7.9-15.1), 0.36 (95% CI, 0.27-0.48), 39.7 (95% CI, 21.4-73.6), and 0.94 (95% CI, 0.85-0.99), respectively, whereas the corresponding numbers for detection of ECR were 0.95 (95% CI, 0.91-0.98), 0.91 (95% CI, 0.86-0.94), 8.8 (95% CI, 6.0-12.7), 0.08 (95% CI, 0.05-0.15), 171.7 (95% CI, 67.9-434.3), and 0.97 (95% CI, 0.95-0.98), respectively. The overall diagnostic accuracy (Q* index) in LNM and ECR were 0.88 and 0.93, respectively.

CONCLUSION

(18)F-FDG PET/CT has an excellent diagnostic performance for detecting LNM preoperatively and disease recurrence postoperatively in endometrial cancer patients.

Preoperative PET/CT standardized FDG uptake values of pelvic lymph nodes as a significant prognostic factor in patients with endometrial cancer

PURPOSE

Using integrated PET/CT, we evaluated the prognostic relevance of preoperative pelvic lymph node (LN) (18)F-FDG uptake in endometrioid endometrial cancer.

METHODS

We retrospectively reviewed patients with pathologically proven endometrial cancer who underwent preoperative (18)F-FDG PET/CT scans to evaluate the prognostic significance of PET/CT parameters and other clinicopathological variables. We used Cox proportional hazards regression to examine the relationship between recurrence and the maximum standardized uptake value (SUVmax) in pelvic LNs (SUVLN) on FDG PET/CT.

RESULTS

Clinical data, treatment modalities and results were reviewed in 70 eligible patients. The median postsurgical follow-up was 29 months (range 6 to 95 months). Receiver-operating characteristic analysis identified the significant SUVLN cut-off value as 15. The SUVLN correlated with FIGO stage (P < 0.001), LN metastasis (P < 0.001), lymphovascular space invasion (P < 0.001), SUVtumour (P = 0.001), metastatic LN size (P = 0.004), primary tumour size (P = 0.012), tumour grade (P = 0.015) and depth of tumour invasion (P = 0.035). Regression analysis showed a statistically significant association between recurrence and SUVLN (P = 0.002). Recurrence differed significantly (P < 0.001) between patients with SUVLN >15 and those with SUVLN ≤15.

CONCLUSION

Preoperative pelvic LN FDG uptake exhibited a strong significant association with recurrence of endometrioid endometrial cancer.

Prognostic value of fluorine-18-fluorodeoxyglucose positron emission tomography or PET-computed tomography in cervical cancer: a meta-analysis

OBJECTIVE

We pooled the data from published studies to estimate the prognostic value of fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) or PET/computed tomography (CT) in cervical cancer patients.

METHODS

We searched MEDLINE, EMBASE, and PUBMED to identify studies investigating the association of 18F-FDG PET or PET/CT with clinical survival outcomes of patients with cervical cancer. The summarized hazard ratio (HR) was estimated by using fixed- or random-effect model according to heterogeneity between trails.

RESULTS

We analyzed a total number of 1854 patients from 16 studies and found that positive pretreatment FDG-PET images were significantly associated with poorer event-free survival (hazard ratio [HR], 2.681; 95% confidence interval [CI], 2.059-3.490) and overall survival (HR, 2.063; 95% CI, 1.023-4.158). Furthermore, metabolic response of therapy as shown on posttreatment PET images was also capable of predicting event-free survival and overall survival with statistical significance, and the HR was 2.030 (95% CI, 1.537-2.681) and 2.322 (95% CI, 1.485-3.630), respectively.

CONCLUSIONS

Uptake of 18F-FDG on PET or PET/CT either before or after treatment has a promising value of both predicting survival outcomes for patients with cervical cancer and identifying patients for more aggressive treatment.

Estrogen and progesterone regulate p27kip1 levels via the ubiquitin-proteasome system: pathogenic and therapeutic implications for endometrial cancer

The levels of proteins that control the cell cycle are regulated by ubiquitin-mediated degradation via the ubiquitin-proteasome system (UPS) by substrate-specific E3 ubiquitin ligases. The cyclin-dependent kinase inhibitor, p27kip1 (p27), that blocks the cell cycle in G1, is ubiquitylated by the E3 ligase SCF-Skp2/Cks1 for degradation by the UPS. In turn, Skp2 and Cks1 are ubiquitylated by the E3 ligase complex APC/Cdh1 for destruction thereby maintaining abundant levels of nuclear p27. We previously showed that perpetual proteasomal degradation of p27 is an early event in Type I endometrial carcinogenesis (ECA), an estrogen (E2)-induced cancer. The present studies demonstrate that E2 stimulates growth of ECA cell lines and normal primary endometrial epithelial cells (EECs) and induces MAPK-ERK1/2-dependent phosphorylation of p27 on Thr187, a prerequisite for p27 ubiquitylation by nuclear SCF-Skp2/Cks1 and subsequent degradation. In addition, E2 decreases the E3 ligase [APC]Cdh1 leaving Skp2 and Cks1 intact to cause p27 degradation. Furthermore, knocking-down Skp2 prevents E2-induced p27 degradation and growth stimulation suggesting that the pathogenesis of E2-induced ECA is dependent on Skp2-mediated degradation of p27. Conversely, progesterone (Pg) as an inhibitor of endometrial proliferation increases nuclear p27 and Cdh1 in primary EECs and ECA cells. Pg, also increases Cdh1 binding to APC to form the active E3ligase. Knocking-down Cdh1 obviates Pg-induced stabilization of p27 and growth inhibition. Notably, neither E2 nor Pg affected transcription of Cdh1, Skp2, Cks1 nor p27. These studies provide new insights into hormone regulation of cell proliferation through the UPS. The data implicates that preventing nuclear p27 degradation by blocking Skp2/Cks1-mediated degradation of p27 or increasing Cdh1 to mediate degradation of Skp2-Cks1 are potential strategies for the prevention and treatment of ECA.