Early response of patients undergoing concurrent chemoradiotherapy for cervical cancer: a comparison of PET/CT and MRI

The use of PET/MRI in radiotherapy

Positron emission tomography/magnetic resonance imaging (PET/MRI) is a hybrid imaging technique that quantitatively combines the metabolic and functional data from positron emission tomography (PET) with anatomical and physiological information from MRI. As PET/MRI technology has advanced, its applications in cancer care have expanded. Recent studies have demonstrated that PET/MRI provides unique advantages in the field of radiotherapy and has become invaluable in guiding precision radiotherapy techniques. This review discusses the rationale and clinical evidence supporting the use of PET/MRI for radiation positioning, target delineation, efficacy evaluation, and patient surveillance.Critical relevance statement This article critically assesses the transformative role of PET/MRI in advancing precision radiotherapy, providing essential insights into improved radiation positioning, target delineation, efficacy evaluation, and patient surveillance in clinical radiology practice.Key points• The emergence of PET/MRI will be a key bridge for precise radiotherapy.• PET/MRI has unique advantages in the whole process of radiotherapy.• New tracers and nanoparticle probes will broaden the use of PET/MRI in radiation.• PET/MRI will be utilized more frequently for radiotherapy.

Changes on Midchemoradiation Therapy Fluorodeoxyglucose Positron Emission Tomography for Cervical Cancer Are Associated with Prognosis

PURPOSE

To assess whether radiographic and metabolic changes on midchemoradiation therapy (CRT) fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT) for cervical cancer predict outcome.

METHODS AND MATERIALS

Women with International Federation of Gynecology and Obstetrics stage IB1-IVB cervical cancer treated with concurrent cisplatin-based CRT and brachytherapy were enrolled on a single-institution prospective clinical trial; FDG-PET/CT was obtained before CRT and at 30 to 36 Gy. Max and mean standard uptake values, metabolic tumor volume, and total lesion glycolysis (TLG) for the primary tumor and clinically involved lymph nodes from the pre-CRT and intra-CRT FDG-PET/CT were recorded. Clinical endpoints analyzed include overall survival (OS), disease-free survival (DFS), and rates of cervical recurrence (CR), nodal recurrence (NR), and distant metastasis (DM). FDG-PET/CT variables and other prognostic factors associated with clinical endpoints were identified via univariate Cox proportional hazards modeling and competing risk analysis.

RESULTS

Thirty women were enrolled from 2012 to 2016. After a median follow-up of 24 months, 2-year rates of OS, DFS, DM, NR, and CR were 68% (95% confidence interval [CI], 51%-85%), 44% (95% CI, 26%-63%), 42% (95% CI, 23%-59%), 14% (95% CI, 4%-30%), and 10% (95% CI, 2%-24%), respectively. Intra-PET metrics and TLG across all PET scans were most consistently associated with OS, DFS, DM, and NR on univariate analysis. Intra-CRT TLG was associated with OS (hazard ratio [HR] 1.35; 95% CI, 1.15-1.55; P = .001), DFS (HR 1.19; 95% CI, 1.04-1.34; P = .018), and NR (HR 1.25; 95% CI, 1.10-1.40; P = .002). No absolute or relative changes between parameters of baseline and mid-CRT FDG-PET/CT were associated with disease outcomes on univariate analysis, with the exception of relative change in mean standard uptake values and CR (P = .004).

CONCLUSIONS

In this group of patients with high-risk cervical cancer treated with CRT and brachytherapy, TLG and metabolic tumor volume on intra-CRT FDG-PET/CT was associated with OS. These metrics may provide an early signal for selective treatment intensification with either dose escalation or adjuvant chemotherapy.

Magnetic resonance imaging after external beam radiotherapy and concurrent chemotherapy for locally advanced cervical cancer helps to identify patients at risk of recurrence

OBJECTIVE

Tumor volume and regression after external beam radiotherapy have been shown to be accurate parameters to assess treatment response via magnetic resonance imaging (MRI). The aim of the study was to evaluate the prognostic value of tumor size reduction rate after external beam radiotherapy and chemotherapy prior to brachytherapy.

METHODS

Patients with locally advanced cervical cancer treated at two French comprehensive cancer centers between 1998 and 2010 were included. Treatment was pelvic external beam radiotherapy with platinum based chemotherapy followed by brachytherapy. Records were reviewed for demographic, clinical, imaging, treatment, and follow-up data. Anonymized linked data were used to ascertain the association between pre-external and post-external beam radiotherapy MRI results, and survival data.

RESULTS

185 patients were included in the study. Median age at diagnosis was 45 years (range 26-72). 77 patients (41.6%) were International Federation of Gynecology and Obstetrics stage IB2-IIA disease and 108 patients (58.4%) were stage IIB-IVA. Median tumor size after external beam radiotherapy and chemotherapy was 2.0 cm (range 0.0-8.0) and median tumor size reduction rate was 62.4% (range 0.0-100.0%). Tumor size and tumor reduction rate at 45 Gy external beam radiotherapy MRI were significantly associated with local recurrence free survival (P<0.001), disease free survival, and overall survival (P<0.05). Tumor reduction rate ≥60% was significantly associated with a decreased risk of relapse and death (HR (95% CI) 0.21 (0.09 to 0.50), P=0.001 for local recurrence free survival; 0.48 (0.30 to 0.77) P=0.002 for disease free survival; and 0.51 (0.29 to 0.88), P=0.014 for overall survival).

CONCLUSIONS

Tumor size reduction rate >60% between pre-therapeutic and post-therapeutic 45 Gy external beam radiotherapy with concurrent chemotherapy was associated with improved survival. Future studies may help to identify patients who may ultimately benefit from completion surgery, adjuvant chemotherapy, and closer follow-up.

Does Routine Posttreatment PET/CT Add Value to the Care of Women With Locally Advanced Cervical Cancer?

OBJECTIVES

The aim of this study was to determine the necessary reduction in recurrence rate that would make postchemoradiation positron emission tomography (PET)/computed tomography (CT) to direct completion hysterectomy for locally advanced cervical cancer (LACC) cost-effective.

METHODS

A decision model evaluated costs and recurrence rates of 2 posttreatment surveillance strategies in LACC: (1) routine surveillance without PET/CT and (2) PET/CT after 3 months to triage to completion hysterectomy. Incremental cost-effectiveness ratios were expressed in dollars per additional cancer recurrence avoided. Model parameters included expected rates of recurrence using each strategy, true- and false-positive rates of posttreatment PET/CT, and major complications of completion hysterectomy. From published data, we modeled an LACC baseline recurrence rate of 32%, PET/CT false-positive rate of 33%, and false-negative rate of 19%. We assumed that PET/CT revealed persistent local cervical cancer in 16% and progressive or distant disease in 6%. Costs of PET/CT, hysterectomy, and treatment for recurrence were based on Medicare reimbursements. A 50% salvage rate with hysterectomy was assumed and varied in sensitivity analysis.

RESULTS

Routine use of PET/CT to direct completion hysterectomy was associated with a higher average cost ($16,579 vs $15,450) and a lower recurrence rate (26% vs 32%). The incremental cost-effectiveness ratio of PET was $20,761 per recurrence prevented. When the probability of recurrence after hysterectomy dropped to 25% or less, PET/CT was a dominant strategy.

CONCLUSIONS

Routine use of PET/CT to determine which patients may benefit from a completion hysterectomy after chemoradiation for LACC has the potential to be highly cost-effective.

Utility of (18)F-FDG PET/CT in patients with advanced squamous cell carcinoma of the uterine cervix receiving concurrent chemoradiotherapy: a parallel study of a prospective randomized trial

PURPOSE

The aim of this prospective study was to assess the usefulness of (18)F-FDG PET/CT performed before and during treatment for predicting treatment failure in patients with advanced squamous cell carcinoma of the uterine cervix treated with concurrent chemoradiotherapy (CCRT).

METHODS

Patients with cervical squamous cell carcinoma, International Federation of Gynecology and Obstetrics stage III/IVA or positive pelvic or paraaortic lymph node (LN) metastasis without other distant metastasis on PET/CT entering a randomized trial of CCRT (AGOG 09-001) were eligible. PET/CT scans were performed at baseline, during week 3 of CCRT and 2 - 3 months after CCRT. PET/CT parameters were correlated with sites of failure and overall survival (OS). The resulting predictors developed from the study cohort were validated on two independent datasets using area under the curve values, sensitivities and specificities.

RESULTS

With a median follow-up of 54 months for survivors, 20 (36 %) of the 55 eligible patients were proven to have treatment failure. Sites of failure were local in five, regional in 11, and distant in 11. Four predictors for local failure, three for regional failure, and four for distant failures were identified. After validation with two independent cohorts of 31 and 105 patients, we consider the following as clinically useful predictors: pretreatment metabolic tumour volume (MTV) and during-treatment cervical tumour MTV for local failure; during-treatment SUVnode (maximum standardized uptake value of LNs) for regional and distant failure, and during-treatment MTV for distant failure. During-treatment SUVnode (P = .001) and cervical tumour MTVratio (P = .004) were independent significant predictors of OS by stepwise Cox regression.

CONCLUSION

PET/CT imaging before and during treatment is useful for predicting failure sites and OS, making tailored therapeutic modifications feasible with potential outcome improvement during primary therapy.

PET-CT in the UK: current status and future directions

Combined positron-emission tomography and computed tomography (PET-CT) has taken the oncological world by storm since being introduced into the clinical domain in the early 21(st) century and is firmly established in the management pathway of many different tumour types. Non-oncological applications of PET-CT represent a smaller but steadily growing area of interest. PET-CT continues to be the focus of a large number of research studies and keeping up-to-date with the literature is important but represents a challenge. Consequently guidelines recommending PET-CT usage need to be revised regularly to encompass new developments. The purpose of this article is twofold: first, it provides a detailed review of the evidence-base underpinning the major uses of PET-CT in clinical practice, which may be of value to a wide-range of individuals, including those directly involved with PET-CT and to a much larger group with limited exposure, but for whom a précis of the current state-of-play may help inform other radiology and multidisciplinary team (MDT) work; the second purpose is as a companion to revised guidelines on evidence-based indications for PET-CT in the UK (being published concurrently) providing a detailed commentary on new indications with a summary of emerging data supporting these additional clinical uses of the technique.

Validity of 18F-fluorodeoxyglucose positron emission tomography/computed tomography for pretreatment evaluation of patients with cervical carcinoma: a retrospective pathology-matched study

OBJECTIVE

The aim of this study was to evaluate the validity of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) for pretreatment evaluation of patients with cervical carcinoma.

METHODS

Retrospective evaluation of 63 patients, diagnosed with stage IA-IIA cervical carcinoma who underwent 18F-FDG PET/CT before surgery, was performed. Sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratios (LRs) of PET/CT for predicting the positive cervix, vagina, uterine body, and lymph node invasion at the surgical specimen was calculated.

RESULTS

Sensitivity, specificity, positive predictive value, and negative predictive value of the positive cervix invasion in PET/CT to detect positive surgical specimen were 88.2%, 75%, 93.8%, and 60%, respectively. The LR+ ratio was 3.5, and the LR- ratio was 0.2. Sensitivity, specificity, positive predictive value, and negative predictive value of the positive vagina invasion in PET/CT to detect positive surgical specimen were 100%, 70.97%, 5.3%, and 100%, respectively. The LR+ ratio was 3.4, and the LR- ratio was 0. Sensitivity, specificity, positive predictive value, and negative predictive value of the positive uterine body invasion in PET/CT to detect positive surgical specimen were 75%, 83.1%, 23.1%, and 98%, respectively. The LR+ ratio was 4.4, and the LR- ratio was 0.3. Sensitivity, specificity, positive predictive value, and negative predictive value of the positive lymph node invasion in PET/CT to detect positive surgical specimen were 87.5%, 78.4%, 38.9%, and 97.6%, respectively. The LR+ ratio was 4.1, and the LR- ratio was 0.2.

CONCLUSIONS

The cervix invasion, negative uterine body invasion, and negative lymph node invasion are effective 18F-FDG PET/CT findings.

The Role of (18) F-FDG PET/CT in Assessing Therapy Response in Cervix Cancer after Concurrent Chemoradiation Therapy

PURPOSE

To determine whether persisting cervical fluorodeoxyglucose (FDG) uptake after concurrent chemoradiotherapy (CCRT) for cervical cancer can reflect residual malignancy.

METHODS

F-FDG PET/CT was performed before and after CCRT in 136 patients with cervical cancer. The maximum and mean standardized uptake values (SUVmax and SUVmean) were recorded from PET/CT scans performed pre- and post-treatment. SUVs were correlated with treatment response after CCRT. Final treatment response was determined by MRI and further follow-up PET/CT. One hundred four of 136 patients underwent pelvic MRI, and 32 of 136 patients underwent further follow-up PET/CT. Patients were classified into two categories: patients with residual tumor or patients without residual tumor (complete responder). Pre- and post-treatment serum squamous cell carcinoma antigen (SCC) levels were also recorded for comparison. The optimal cutoff value of SUVmax for predicting residual cervical tumor was determined using receiver-operating characteristic (ROC) analysis.

RESULTS

Of 136 patients, 124 showed complete response on further follow-up studies and 12 were confirmed to have residual tumor. The post-treatment SUVmax and pre-/post-treatment SUVmean of complete responders were significantly lower than those of patients with residual tumor: 2.5 ± 0.8 and 7.2 ± 4.2/1.9 ± 0.7 for complete responders and 5.7 ± 2.6 and 12.8 ± 6.9/3.7 ± 0.7 for patients with residual tumor (p < 0.05). The pre-treatment SUVmax and pre-/post-treatment serum SCC levels of the complete responders tended to be lower than those of patients with residual tumor, but this did not have statistical significance. Using ROC analysis, an optimal cutoff SUVmax of 4.0 on the post-treatment PET/CT yielded a sensitivity, specificity, positive predictive value, and negative predictive value of 92 %, 94 %, 61 %, and 99 %, respectively (p < 0.001).

CONCLUSIONS

Persistent cervical FDG uptake in(18)F-FDG PET/CT after CCRT for cervical cancer may be caused by residual tumor or post-therapy inflammation. A higher cutoff SUVmax than conventional criteria for cervical cancer in post-CCRT PET/CT might help to detect residual tumor.

Application of FDG-PET/CT in Radiation Oncology

Positron emission tomography (PET)/computed tomography (CT), which combines the advantages of high sensitivity and specificity of PET and high resolution of CT, is a unique tool for cancer management. PET/CT has been widely used in cancer diagnosis and treatment. The article reviews the recent applications of PET/CT in radiation oncology, with a focus on ¹⁸F-fluorodeoxyglucose (FDG)-PET/CT, addressing the applications in treatment planning and treatment response assessment of radiation therapy.