FDG-PET imaging for the assessment of physiologic volume response during radiotherapy in cervix cancer

PET CT Imaging with FDG in the Therapeutical Management of Locally Advanced Cervical Cancer Diagnosed in a 43-Year-Old Patient: Case Report and Review of the Literature

Background: Cervical cancer is the most important cancer type found in women throughout the world. Numerous research studies are being performed to investigate the effectiveness of different strategies for the imaging and treatment of locally advanced cervical cancer, which are showing favorable outcomes. Brachytherapy is characterized by the application of very high radiation doses to target tumor cells with the least exposure to normal tissues. Methods: In the present case study, we report a 43-year-old female patient suffering from cervical cancer belonging to urban origin, with no personal pathological history, who presented herself to the gynecology department of the Bihor County Emergency Clinical hospital with vaginal bleeding. The histopathological examination of the cervix showed squamous cell carcinoma. The treatment was performed with neoadjuvant chemotherapy and concurrent chemoradiotherapy. Results: According to the clinical and histopathological examination, a diagnosis of non-keratinizing squamous carcinoma of the uterine cervix at FIGO stage III C1 was established. Radio-chemotherapy was performed, as well as periodic imaging assessments with a CT of the chest, pelvis, and abdomen, without local and distant relapse. FDG PET imaging was performed for the management and follow-up of cervical cancer by retrieving the SUVmax value. Conclusions: The post-therapeutic complications are represented by the vaginal stenosis installed 6 months after the end of the radiotherapeutic treatment.

Early Metabolic Response Assessed Using 18F-FDG-PET/CT for Image-Guided Intracavitary Brachytherapy Can Better Predict Treatment Outcomes in Patients with Cervical Cancer

PURPOSE

This study aimed to identify the prognostic value of early metabolic response assessed using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) during radiation therapy (RT) for cervical cancer.

MATERIALS AND METHODS

We identified 116 patients treated with definitive RT, including FDG-PET/CT-guided intracavitary brachytherapy, between 2009 and 2018. We calculated parameters including maximum (SUVmax) and mean standardized uptake values (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for baseline FDG-PET/CT (PETbase) and image-guided brachytherapy planning FDG-PET/CT (PETIGBT). Multivariable analyses of disease-free survival (DFS) and overall survival (OS) were performed.

RESULTS

We observed a time-dependent decrease in PET parameters between PETbase and PETIGBT; ΔSUVmax, ΔSUVmean, ΔMTV, and ΔTLG were 65%, 61%, 78%, and 93%, respectively. With a median follow-up of 59.5 months, the 5-year DFS and OS rates were 66% and 79%, respectively. Multivariable analysis demonstrated that ΔSUVmax ≥ 50% was associated with favorable DFS (hazard ratio [HR], 2.56; 95% confidence interval [CI], 1.14 to 5.77) and OS (HR, 5.14; 95% CI, 1.55 to 17.01). Patients with ΔSUVmax ≥ 50% (n=87) showed better DFS and OS than those with ΔSUVmax < 50% (n=29) (DFS, 76% vs. 35%, p < 0.001; OS, 90% vs. 41%, p < 0.001, respectively). Adenocarcinoma was frequently observed in ΔSUVmax < 50% compared to ΔSUVmax ≥ 50% (27.6% vs. 10.3%, p=0.003). In addition, models incorporating metabolic parameters showed improved accuracy for predicting DFS (p=0.012) and OS (p=0.004) than models with clinicopathologic factors.

CONCLUSION

Changes in metabolic parameters, especially those in SUVmax by > 50%, can help improve survival outcome predictions for patients with cervical cancer treated with definitive RT.

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.

(18F)-FDG PET/CT parameters to predict survival and recurrence in patients with locally advanced cervical cancer treated with chemoradiotherapy

PURPOSE

To identify predictive (¹⁸F)-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT)-based parameters for locoregional control, disease-free survival and overall survival, by testing different thresholds of metabolic tumor volume and total lesion glycolysis in patients with locally-advanced cervical cancer.

PATIENTS AND METHODS

Thirty-seven patients treated with standard chemoirradiation underwent a pretreatment (¹⁸F)-FDG-PET/CT. Using different thresholds of maximum standardized uptake value, the following PET parameters were computed: maximum standardized uptake value, mean standardized uptake value, metabolic tumor volume and total lesion glycolysis for primary tumor and lymph nodes and a new parameter combining the metabolic tumor volume and the distance between lymph nodes and the primary tumor, namely metabolic node distance. Correlation between PET and clinical parameters with clinical outcome (overall survival, disease-free survival, and locoregional control) was assessed using univariate and multivariate analyses (Cox model).

RESULTS

In univariate analyses, PET/CT parameters associated with overall survival and disease-free survival were: metabolic tumor volume and total lesion glycolysis of the primary tumor, total lesion glycolysis of lymph nodes and metabolic node distance. The most predictive threshold segmentation for metabolic tumor volume and total lesion glycolysis was 48% of maximum standardized uptake value for the primary tumor and 30% for the lymph nodes. In multivariate Cox analysis, the total lesion glycolysis of primary tumor 48% and metabolic node distance were the two independent risk factors for overall survival (P<0.01), disease-free survival (P<0.01) and locoregional control (P=0.046).

CONCLUSION

Total lesion glycolysis of primary tumor and distance between the invaded positive lymph node and the primary tumor seem to have the highest predictive value when compared to classical clinical prognostic parameters and may be useful to identify high risk groups at time of diagnosis and to tailor the therapeutic approach in locally-advanced cervical cancer.

The value of pre- and post-neoadjuvant chemotherapy F-18 FDG PET/CT scans in breast cancer: comparison with MRI

Background Accurate assessment of neoadjuvant chemotherapy (NAC) response with positron emission tomography/computed tomography (PET/CT) or magnetic resonance imaging (MRI) may provide appropriate operation guidelines for individual breast cancer patients. Purpose To compare the values of PET/CT and MRI for response evaluation following NAC in breast cancer patients. Material and Methods Thirty-three consecutive patients who underwent NAC were included. PET/CT and MRI were performed before and one to four weeks after NAC. With response evaluation of PET/CT and MRI, patients with complete/partial responses on imaging studies were considered to be responders, and those showing stable/progressive disease non-responders. Peak standardized uptake value corrected for lean body mass (SULpeak) and metabolic tumor volume (MTV) were measured from PET/CT, and unidimensional diameter (1D) and tumor volume (TV) from MRI. Reduction rates for each parameter were calculated (Δ%SULpeak, Δ%MTV, Δ%1D, and Δ%TV). The pathological response for NAC as reference was evaluated after surgical resection of the remaining tumor in the breast. Results We identified 17 pathological responders and 16 non-responders. PET/CT had lower specificity and accuracy, but higher sensitivity than MRI, although no significant difference was found between PET/CT and MRI. Following NAC, there were significant differences between pathological responders and non-responders in SULpeak ( P < 0.001), MTV ( P < 0.001), 1D ( P = 0.0003), TV ( P = 0.038), Δ%SULpeak ( P = 0.001), Δ%MTV ( P < 0.001), Δ%1D ( P < 0.001), and Δ%TV ( P = 0.001). Conclusion PET/CT showed lower specificity and accuracy than MRI in evaluating responses to NAC, but both PET/CT and MRI parameters may have predictive value in distinguishing therapeutic responders and non-responders following NAC.

Use of Metabolic Parameters as Prognostic Factors During Concomitant Chemoradiotherapy for Locally Advanced Cervical Cancer

OBJECTIVES

To investigate the use of metabolic parameters as early prognostic factors during concomitant chemoradiotherapy for locally advanced cervix carcinoma (LACC).

MATERIALS AND METHODS

Between February 2008 and January 2012, 34 consecutive patients treated for LACC (International Federation of Gynecology and Obstetrics Staging System stage IB2-IVA) were included in a retrospective study. Treatment was standard of care: total dose of 45 Gy in 1.8 Gy per fraction with concurrent cisplatin followed by brachytherapy. 18F-FDG PET-CT modalities were performed before treatment and per-treatment (at 40 Gy). The analyzed parameters were: maximum standardized uptake value (SUVmax), SUVmax variations of the primary tumor between the 2 investigations (DSUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). Survival was assessed according to early metabolic changes during chemoradiotherapy.

RESULTS

Median follow-up was 16 months (range, 5.3 to 32.4 mo). Median SUVmax before treatment was 13.15 (5.9 to 31) and was 5.05 (0 to 12) per-treatment. Median DSUVmax was 63.97% (0% to 100%). Median MTV before treatment was 44.16 mL (3.392 to 252.768 mL) and was 5.44 mL (0 to 69.88 mL) per-treatment. Median TLG before treatment was 249.82 mL (13.40 to 1931.10 mL) and was 20.14 mL (0 to 349.99 mL) per-treatment. At 40 Gy, SUVmax≥6, DSUVmax≤40%, MTV≥5.6 mL, and TLG≥21.6 mL were significantly associated with overall survival and progression-free survival reduction. MTV predicted progression with a sensitivity of 80% and a specificity of 87.5% and TLG with a sensitivity of 80% and a specificity of 83.3%.

CONCLUSIONS

PET-CT imaging could be useful as an early prognostic factor during treatment for LACC. MTV and TLG seem to provide better prognostic information than SUVmax and DSUVmax.

Random forests to predict tumor recurrence following cervical cancer therapy using pre- and per-treatment 18F-FDG PET parameters

The ability to predict tumor recurrence after chemoradiotherapy of locally advanced cervical cancer is a crucial clinical issue to intensify the treatment of the most high-risk patients. The objective of this study was to investigate tumor metabolism characteristics extracted from pre- and per-treatment ¹⁸F-FDG PET images to predict 3-year overall recurrence (OR). A total of 53 locally advanced cervical cancer patients underwent pre- and per-treatment ¹⁸F-FDG PET (respectively PET1 and PET2). Tumor metabolism was characterized through several delineations using different thresholds, based on a percentage of the maximum uptake, and applied by region-growing. The SUV distribution in PET1 and PET2 within each segmented region was characterized through 7 intensity and histogram-based parameters, 9 shape descriptors and 16 textural features for a total of 1026 parameters. Predictive capability of the extracted parameters was assessed using the area under the receiver operating curve (AUC) associated to univariate logistic regression models and random forest (RF) classifier. In univariate analyses, 36 parameters were highly significant predictors of 3-year OR (p<;0.01), AUC ranging from 0.72 to 0.83. With RF, the Out-of-Bag (OOB) error rate using the totality of the extracted parameters was 26.42% (AUC=0.72). By recursively eliminating the less important variables, OOB error rate of the RF classifier using the nine most important parameters was 13.21% (AUC=0.90). Results suggest that both pre- and per-treatment ¹⁸F-FDG PET exams provide meaningful information to predict the tumor recurrence. RF classifier is able to handle a very large number of extracted features and allows the combination of the most prognostic parameters to improve the prediction.

Weighted quantification of ¹⁸F-FDG tumor metabolism activity using fuzzy-thresholding to predict post-treatment tumor recurrence

Cervical cancer is one of the most common cancer to affect women worldwide. Despite the efficiency of radiotherapy treatment, some patients present post-treatment tumor recurrence which increases the risk of death. Early outcome prediction could help oncologists to adapt the treatment. Several studies suggest that quantification of tumor activity using (18)FFDG PET imaging could be used to predict post-treatment tumor recurrence. In this paper we study the predictive value of weighted quantification of tumor metabolism extracted by fuzzy-thresholding for tumor recurrence of locally advanced cervical cancer. Fifty-three patients with locally advanced cervical cancer treated by chemo-radiotherapy were considered in our study. For each patient, a coregistered (18)F-FDG PET/CT scan was acquired before the treatment and was segmented using different hard and fuzzy segmentations methods. The tumor activity was extracted through the total lesion glycolysis and through a weighted analog of the total lesion glycolysis using the probability maps provided by the fuzzy segmentations. Outcomes prediction was performed using the area under the receiver operating characteristic curve (AUC) and the Harrell's C-index. Results suggest that weighted quantification of tumor activity seems to be strongly informative and could be used to predict post-treatment tumor recurrence in cervical cancer.

Appropriateness criteria of FDG PET/CT in oncology

(18)Fluorine-2-fluoro-2-Deoxy-d-glucose ((18)F-FDG) positron emission tomography/computerized tomography (PET/CT) is a well-established functional imaging method widely used in oncology. In this article, we have incorporated the various indications for (18)FDG PET/CT in oncology based on available evidence and current guidelines. Growing body of evidence for use of (18)FDG PET/CT in select tumors is also discussed. This article attempts to give the reader an overview of the appropriateness of using (18)F-FDG PET/CT in various malignancies.

The role of PET/CT in the management of cervical cancer

OBJECTIVE. Cervical cancer is the second most common malignancy in women worldwide and the third most common cause of cancer mortality in the United States. The aim of this article is to describe cervical cancer and outline the value of (18)F-FDG PET/CT in the management of cervical malignancy. CONCLUSION. The value of PET/CT has been found in staging and treatment strategy for cervical cancer. FDG PET/CT facilitates decision-making and radiation treatment planning and provides important information about treatment response, disease recurrence, and long-term survival.

The role of PET/CT in cervical cancer

In locally advanced cervical cancer, ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography – computed tomography (PET/CT) has become important in the initial evaluation of disease extent. It is superior to other imaging modalities for lymph node status and distant metastasis. PET-defined cervical tumor volume predicts progression-free and overall survival. Higher FDG uptake in both primary and regional lymph nodes is strongly predictive of worse outcome. FDG-PET is useful for assessing treatment response 3 months after completing concurrent chemo-radiotherapy (CRT) and predicting long-term survival, and in suspected disease recurrence. In the era of image-guided adaptive radiotherapy, accurately defining disease areas is critical to avoid irradiating normal tissue. Based on additional information provided by FDG-PET, radiation treatment volumes can be modified and higher doses to FDG-positive lymph nodes safely delivered. FDG-PET/CT has been used for image-guided brachytherapy of FDG-avid tumor volume, while respecting low doses to bladder and rectum. Despite survival improvements due to CRT in cervical cancer, disease recurrences continue to be a major problem. Biological rationale exists for combining novel non-cytotoxic agents with CRT, and drugs targeting specific molecular pathways are under clinical development. The integration of these targeted therapies in clinical trials, and the need for accurate predictors of radio-curability is essential. New molecular imaging tracers may help identifying more aggressive tumors. ⁶⁴Cu-labeled diacetyl-di(N(4)-methylthiosemicarbazone) is taken up by hypoxic tissues, which may be valuable for prognostication and radiation treatment planning. PET/CT imaging with novel radiopharmaceuticals could further impact cervical cancer treatment as surrogate markers of drug activity at the tumor microenvironment level. The present article reviews the current and emerging role of PET/CT in the management of cervical cancer.

Advances in clinical research in gynecologic radiation oncology: an RTOG symposium

There have been inexorable improvements in gynecologic radiation oncology through technologically advances, 3-dimensional imaging, and clinical research. Investment in these 3 critical areas has improved, and will continue to improve, the lives of patients with gynecologic cancer. Advanced technology delivery in gynecologic radiation oncology is challenging owing to the following: (1) setup difficulties, (2) managing considerable internal organ motion, and (3) responding to tumor volume reduction during treatment. Image guidance is a potential route to solve these problems and improve delivery to tumor and sparing organs at risk. Imaging with positron emission tomography-computed tomography and magnetic resonance imaging are contributing significantly to improved accuracy in diagnosis, treatment, and follow-up in cancer of the cervix. Functional imaging by exploiting tumor biology may improve prognosis and treatment. Clinical trials have been the greatest mechanism to improve and establish standards of care in women with vulvar, endometrial, and cervical cancer. There have been multiple technological advances and practice changing trials within the past several decades. Many important questions remain in optimizing care for women with gynecologic malignancies. The performance of clinical trials will be advanced with the use of consistent language (ie, similar staging system and criteria), eligibility criteria that fit the research question, end points that matter, adequate statistical power, complete follow-up, and prompt publication of mature results.

Evidence for the use PET for radiation therapy planning in patients with cervical cancer: a systematic review

BACKGROUND AND OBJECTIVE

In recent years, the role of positron emission tomography (PET) in the staging and management of gynecological cancers has been increasing. The aim of this study was to systematically review the role of PET in radiotherapy planning and brachytherapy treatment optimization in patients with cervical cancer.

DESIGN AND SETTING

Systematic literature review.

METHODS

Systematic review of relevant literature addressing the utilization of PET and/or PET-computed tomography (CT) in external-beam radiotherapy planning and brachytherapy treatment optimization. We performed an extensive PubMed database search on 20 April 2011. Nineteen studies, including 759 patients, formed the basis of this systematic review.

RESULTS

PET/ PET-CT is the most sensitive imaging modality for detecting nodal metastases in patients with cervical cancer and has been shown to impact external-beam radiotherapy planning by modifying the treatment field and customizing the radiation dose. This particularly applies to detection of previously uncovered para-aortic and inguinal nodal metastases. Furthermore, PET/ PET-CT guided intensity-modulated radiation therapy (IMRT) allows delivery of higher doses of radiation to the primary tumor, if brachytherapy is unsuitable, and to grossly involved nodal disease while minimizing treatment-related toxicity. PET/ PET-CT based brachytherapy optimization allows improved tumor-volume dose distribution and detailed 3D dosimetric evaluation of risk organs. Sequential PET/ PET-CT imaging performed during the course of brachytherapy form the basis of “adaptive” brachytherapy in cervical cancer.

CONCLUSIONS

This review demonstrates the effectiveness of pretreatment PET/ PET-CT in cervical cancer patients treated by radiotherapy. Further prospective studies are required to define the group of patients who would benefit the most from this procedure.

Changes in cervical cancer FDG uptake during chemoradiation and association with response

PURPOSE

Previous research showed that pretreatment uptake of F-18 fluorodeoxyglucose (FDG), as assessed by the maximal standardized uptake value (SUVmax) and the variability of uptake (FDGhetero), predicted for posttreatment response in cervical cancer. In this pilot study, we evaluated the changes in SUVmax and FDGhetero during concurrent chemoradiation for cervical cancer and their association with post-treatment response.

METHODS AND MATERIALS

Twenty-five patients with stage Ib1-IVa cervical cancer were enrolled. SUVmax, FDGhetero, and metabolic tumor volume (MTV) were recorded from FDG-positron emission tomography (PET)/computed tomography (CT) scans performed pretreatment and during weeks 2 and 4 of treatment and were evaluated for changes and association with response assessed on 3-month post-treatment FDG-PET/CT.

RESULTS

For all patients, the average pretreatment SUVmax was 17.8, MTV was 55.4 cm3, and FDGhetero was -1.33. A similar decline in SUVmax was seen at week 2 compared with baseline and week 4 compared with week 2 (34%). The areas of highest FDG uptake in the tumor remained relatively consistent on serial scans. Mean FDGhetero decreased during treatment. For all patients, MTV decreased more from week 2 to week 4 than from pretreatment to week 2. By week 4, the average SUVmax had decreased by 57% and the MTV had decreased by 30%. Five patients showed persistent or new disease on 3-month post-treatment PET. These poor responders showed a higher average SUVmax, larger MTV, and greater heterogeneity at all 3 times. Week 4 SUVmax (P=.037), week 4 FDGhetero (P=.005), pretreatment MTV (P=.008), and pretreatment FDGhetero (P=.008) were all significantly associated with post-treatment PET response.

CONCLUSIONS

SUVmax shows a consistent rate of decline during treatment and declines at a faster rate than MTV regresses. Based on this pilot study, pretreatment and week 4 of treatment represent the best time points for prediction of response.

[((18)F)-fluorodeoxyglucose PET/CT in cervix cancer: lymph node assessment and prognostic/predictive value of primary tumour analysis]

PURPOSE

In cervix carcinoma: (a) to evaluate the ability of ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the lymph node detection; (b) to investigate the prognostic and predictive value of the primary cervical PET parameters.

PATIENTS AND METHODS

Ninety patients treated for cervix carcinoma and evaluated initially by MRI and FGD PET were included. The performances of FDG-PET for lymph node detection (relatively to the lymph node dissection) have been described (sensitivity, specificity, positive predictive value and negative predictive value). PET tumour parameters analyzed were: maximum standard uptake value (SUVmax), the volume and the maximum diameter. The prognostic and predictive values of these parameters were investigated. The tumour response was evaluated on surgical specimens.

RESULTS

PET detected the cervical tumour with a sensitivity of 97% (mean values: SUVmax=15.8, volume=27 mm(3), maximum diameter=47). For the detection of the lymph nodes, the values of sensibility, specificity, positive predictive value and negative predictive value were: 86, 56, 69 and 78% in the pelvic, and 90, 67, 50 and 95% for the para-aortic area, respectively. The SUVmax was correlated with histologic response (P=0.04). The frequency of partial histological response was significantly higher for tumour SUVmax>10.9 (P=0.017). The maximum PET diameter and pathologic response had an impact on disease-free survival and overall survival in multivariate analysis (P<0.05).

CONCLUSION

PET has high sensitivity in detecting pelvic and para-aortic lymph nodes. Some primary cervical tumour PET parameters are useful as prognostic and predictive factors.

Functional Imaging for Assessing Tumor Response in Cancer of the Cervix

Treatment options for carcinoma of the cervix are guided by tumor stage, and include radical surgery, in cases where the tumor is confined to the cervix, or concurrent chemotherapy and radiotherapy. In those cases treated with chemoradiation, the ability to monitor the response to treatment in order to adapt the management plan during its course may be beneficial. This approach has the potential to offer an individualized treatment plan, allowing for differences in behavior between tumors to be addressed early, rather than a ‘one size fits all’ treatment approach. This article aims to review the use of evolving functional imaging techniques including diffusion-weighted MRI, dynamic contrast-enhanced MRI, and PET as tools for the evaluation of response to treatment of uterine cervical carcinoma.

Established, emerging and future applications of FDG-PET/CT in the uterine cancer

Integrated positron emission tomography/computed tomography (PET/CT) with 2-[¹⁸F]fluoro-2-deoxy-D-glucose (FDG) is a useful technique to acquire both glucose metabolic and anatomic imaging data using a single device in a single diagnostic session and has opened a new field in clinical oncologic imaging. FDG-PET/CT has been used successfully for the staging, optimization of treatment, re-staging, therapy monitoring, and prognostic prediction of uterine cervical cancer and endometrial cancer as well as various malignant tumours. The present review discusses the current role of FDG-PET/CT in the management of uterine cancer, discussing its usefulness and limitations in the imaging of these patients.

Clinical evidence on PET-CT for radiation therapy planning in cervix and endometrial cancers

PET-CT plays an increasing role in the diagnosis and treatment of gynaecological cancers. In cervix cancer, whilst MRI remains the best imaging technique for initial primary tumor staging, PET-CT has been showed to be a highly sensitive method to determine lymph node status, except in patients with early-stage cervical cancer where PET-CT cannot replace surgical exploration of pelvic lymph nodes. In patients with advanced cervical cancer, PET-CT has the potential of showing lymph node metastasis not only within the pelvis, but also outside the pelvis, more particularly in the para-aortic area. PET-CT has also been described as a useful tool in 3-D-based adaptative brachytherapy. In endometrial cancer, the issues are different, as the recent decade has seen a therapeutic decrease in early-stage disease, especially in postoperative radiation therapy, whilst more advanced disease have been approached with more aggressive treatments, integrating chemotherapy and external beam radiotherapy. Lymph node status is also an important issue and PET-Scan may replace lymph node surgical procedure particularly in obese patients.

An automatic method for PET target segmentation using a lookup table based on volume and concentration ratio

Accurate evaluation of functionally significant target volumes in combination with anatomic imaging is of primary importance for effective radiation therapy treatment planning. In this study, a method for rapid and accurate PET image segmentation and volumetrics based on phantom measurements and independent of scanner calibration was developed. A series of spheres ranging in volume from 0.5 mL to 95 mL were imaged in an anthropomorphic phantom of human thorax using two commercial PET and CT/PET scanners. The target to background radioactivity concentration ratio ranged from 3:1 to 12:1 in 11 separate phantom scanning experiments. The results confirmed that optimal segmentation thresholding depends on target volume and radioactivity concentration ratio. This information can be derived from a generalized pre-determined "lookup table" of volume and contrast dependent threshold values instead of using fitted curves derived from machine specific information. A three-step method based on the PET image intensity information alone was used to delineate volumes of interest. First, a mean intensity segmentation method was used to generate an initial estimate of target volume, and the radioactivity concentration ratio was computed by a family of recovery coefficient curves to compensate for the partial volume effect. Next, the appropriate threshold value was obtained from a phantom-generated threshold lookup table. Lastly, a threshold level set method was performed on the threshold value to further refine the target contour by reducing the limitation of global thresholding. The segmentation results were consistent for spheres greater than 2.5 mL which yielded volume average uncertainty of 11.2% in phantom studies. The results of segmented volumes were comparable to those determined by contrast-oriented method and iterative threshold method (ITM). In addition, the new volume segmentation method was applied clinically to ten patients undergoing PET/CT volume analysis for radiation therapy treatment planning of solitary lung metastases. For these patients, the average PET segmented volumes were within 8.0% of the CT volumes and were highly dependent on the extension of functionally inactive tumor volume. In summary, the current method does not require fitted threshold curves or a priori knowledge of the CT/MRI target volume. This threshold method can be universally applied to radiation therapy treatment planning with comparable accuracy, and may be useful in the rapid identification and assessment of plans containing multiple targets.

Outcome of patients with incomplete resection after surgery for stage IB2/II cervical carcinoma with chemoradiation therapy

OBJECTIVE

Standard treatment of stage IB2/II cervical carcinoma is chemoradiation therapy. Residual disease is evaluated clinically and by magnetic resonance imaging. The place of surgery after this treatment is debated, except when there is suspicion of residual disease. There is no standard management when surgical resection is incomplete. The aim of this study was to describe the outcome of these patients.

METHODS

A retrospective review was undertaken of patients fulfilling the following inclusion criteria: (1) stage IB2/II cervical cancer, (2) external radiotherapy (45 Gy) with concomitant chemotherapy followed by uterovaginal brachytherapy (15 Gy), (3) magnetic resonance imaging performed between 3 and 8 weeks after brachytherapy, and (4) completion surgery with incomplete resection of pelvic disease. Patients with distant metastasis or carcinosis were excluded.

RESULTS

Ten patients treated between 2003 and 2006 fulfilled all inclusion criteria. The locations of the incomplete resection were (some patients had several locations) the parametrium (n = 4), lateral limit of the cervix (n = 4), anterior (n = 2), posterior (n = 3), and vagina (n = 2). Further surgery had been proposed for 3 patients but only performed once and this patient had rapid disease progression. One patient had received chemotherapy for metastatic para-aortic nodes. Seven patients died with a median period of 11 months after surgery (range, 3-21 months). One patient is alive with recurrent disease, and 2 are free of disease with 23 and 33 months of follow-up.

CONCLUSIONS

The prognosis is poor when resection is incomplete after chemoradiation therapy in advanced-stage cervical cancer, and further surgery does not seem to improve this outcome.

Predicting the response of advanced cervical and ovarian tumors to therapy

The management of advanced cervical and ovarian cancers remains a significant challenge as many women fail to respond to recommended therapy, resulting in disease progression and ultimately patient death. Because of tumor heterogeneity, it is rare for all cancers of a particular type to respond to a specific therapy; and, as a result, many patients receive treatment from which they derive little or no benefit, leading to increased morbidity and undue costs. A marker that could rapidly predict or forecast disease outcome would clearly be beneficial in allowing the administration of a tailored regime for each patient while reducing toxicity and cost. Traditional prognostic factors of tumor size, grade, and stage are not ideal for predicting patient outcome, whereas the use of in vitro assays to detect chemosensitivity or resistance has not yet translated into routine clinical practice. Similarly, biomarkers and tumor markers vary in their predictive ability. DNA array technology offers great promise in predicting the response to therapy based on gene expression profiles, and can allow for targeted therapies against specific molecular alterations that cause disease. Imaging techniques, particularly those with the ability to characterize biological tissues and provide functional, structural, and molecular information, have the potential to noninvasively integrate physical and metabolic information. These include F-18-fluorodeoxyglucose positron emission tomography, dynamic contrast-enhanced magnetic resonance imaging, and diffusion weighted magnetic resonance imaging, all techniques that attempt to evaluate and predict therapy response and so influence clinical outcome. This review examines different methods of predicting the response to treatment in advanced cervical and ovarian tumors.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to describe why prediction of response to therapy for cervical and ovarian cancers is important, describe obstacles to use of in vitro assays to predict outcomes for therapy for ovarian and cervical cancers, and explain potentially new predictive markers.

[Positron emission tomography in the management of cervix cancer patients]

Since its introduction in clinical practice in the 1990's, positron emission tomography (PET), usually with (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG), has become an important imaging modality in patients with cancer. For cervix carcinoma, FDG-PET is significantly more accurate than computed tomography (CT) and is recommended for loco-regional lymph node and extrapelvic staging. The metabolic dimension of the technique provides additional prognostic information. Ongoing studies now concentrate on more advanced clinical applications, such as the planning of radiotherapy, the response evaluation after the induction of therapy, the early detection of recurrence. Technical innovations, such as PET cameras with better spatial resolution and hybrid positron emission tomography/computed tomography (PET-CT), available now on the whole territory, provide both anatomic and metabolic information in the same procedure. From the point of view of biological metabolism, new radiopharmaceutical probes are being developed. Those hold promise for future refinements in this field. This article reviews the current applications of FDG-PET in patients with cervix cancer.

Does the entire uterus need to be treated in cancer of the cervix? Role of adaptive brachytherapy

PURPOSE

To evaluate local control and toxicity by use of a method of adaptive cervical brachytherapy (ACB).

METHODS AND MATERIALS

From 1998 to 2008, we identified 65 cervical cancer patients with FIGO (International Federation of Gynecology and Obstetrics) Stage IB1-IVA disease who received definitive external beam radiation therapy and high-dose rate brachytherapy with tandem and ovoid applicators. As tumors regressed, 45 of 65 patients had the tandem source retracted from the uterine fundus at successive brachytherapy insertions, thus decreasing the number of (192)Ir dwell positions. Tests of trend and Fisher's exact test were used to identify the effect of ACB on disease control and toxicity. Kaplan-Meier analyses were performed to evaluate disease control and late complications.

RESULTS

The median follow-up was 24.5 months. Of the patients, 92% received chemotherapy. The 3-year overall survival, 3-year disease-free survival, 3-year distant metastasis-free survival, and local control rates were 67%, 76%, 79%, and 97%, respectively. There was only 1 isolated local failure, and there were no local failures beyond 1 year. Distant failure was involved in 93% of recurrences. No significant trend was identified regarding the extent of retraction of the tandem source start position with either failure or toxicity. Acute and actuarial 3-year late Grade 3 toxicity or greater occurred in 24.6% and 17% of patients, respectively.

CONCLUSIONS

ACB determined by clinical response yielded excellent local control rates. These data indicate that ACB may be useful in decreasing late toxicities from high-dose rate brachytherapy. With the advent of three-dimensional image-guided brachytherapy, additional methods to adapt treatment technique to changes in tumor volume warrant investigation.

The role of 18F-FDG PET in assessing therapy response in cancer of the cervix and ovaries

For locally advanced cervical cancer, the current literature supports the use of (18)F-FDG PET for assessing treatment response 3 mo after the completion of concurrent chemoradiation. (18)F-FDG PET can provide reliable long-term prognostic information for these patients and, in the future, may be used to guide additional therapy. Investigational areas include the use of (18)F-FDG PET for monitoring response during radiotherapy and chemotherapy in the metastatic and neoadjuvant settings. For ovarian masses, the performance of (18)F-FDG PET in the detection of borderline tumors is limited, and the presence of physiologic (18)F-FDG uptake in normal ovaries of premenopausal women poses another limitation. Preliminary data suggest that the performance of (18)F-FDG PET and (18)F-FDG PET/CT is superior to that of CT alone in initial staging, but the sensitivity of both in the detection of carcinomatosis is limited. Preliminary data also suggest that (18)F-FDG PET may be promising for early prediction of response to chemotherapy and for prediction of response after the completion of chemotherapy. (18)F-FDG PET and (18)F-FDG PET/CT are most helpful in the evaluation of patients with suspected recurrent ovarian carcinoma, especially when CA-125 levels are rising and CT findings are normal or equivocal. PET and CT are complementary, and PET/CT should be used when available. Preliminary data suggest that the addition of (18)F-FDG PET/CT to the evaluation of these patients changes management in approximately a third and reduces overall treatment costs by accurately identifying patients who will or will not benefit from surgery.

Comparison of tumor regression rate of uterine cervical squamous cell carcinoma during external beam and intracavitary radiotherapy

PURPOSE

We compared the radioresponse of cervical carcinoma that was closely related to local disease control by the tumor regression rate (RR) during intracavitary radiotherapy (ICRT) and external beam radiotherapy (EBRT) on the presumption that ICRT has a stronger treatment impact than EBRT because of its specific dose distribution.

MATERIALS AND METHODS

A total of 37 patients were treated by EBRT at 45.0 Gy over 5 weeks, followed by high-dose-rate ICRT at 6.0 Gy per weekly insertion at point A three to five times and by boost EBRT. RR was defined as the slope (day(-1)) of the tumor-volume shrinkage curve fit to an exponential regression equation. Assuming that the tumors were ellipsoid, the tumor volume was estimated using magnetic resonance (MR) images obtained before treatment, after 45.0 Gy of EBRT, and after the third ICRT insertion. RRs were compared based on the radiotherapy method.

RESULTS

RR ranged between -0.008 to 0.093 day(-1) (median 0.021 day(-1)) during EBRT and -0.001 to 0.097 day(-1) (median 0.018 day(-1)) during ICRT, showing no significant difference or correlation between treatments.

CONCLUSION

Contrary to expectations, RR did not directly relate to the impact of physical treatment. RR could be related to biological factors, such as the amount of tumor clearance and changes in tumor consistency during treatment.

Intratumoral metabolic heterogeneity of cervical cancer

PURPOSE

Previous research has shown that the intertumoral maximum standardized uptake value (SUVMax) of F-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET) for cervical cancer predicts disease outcome. The purpose of this study was to evaluate the pretreatment intratumoral metabolic heterogeneity of FDG.

EXPERIMENTAL DESIGN

This is a prospective cohort study of 72 patients with International Federation of Gynecology and Obstetrics stages Ib1 to IVa cervical cancer treated with chemoradiation. Three-dimensional FDG-PET threshold tumor volumes were calculated using image segmentation and an adaptive thresholding method for the primary cervix tumor from the pretreatment FDG-PET/computerized tomography. Intratumor heterogeneity was obtained for each patient's cervical tumor by taking the derivative (dV/dT) of the volume-threshold function from 40% to 80%. The association between intratumoral heterogeneity and tumor-specific factors and patient outcomes were determined.

RESULTS

The mean cervix tumor SUV(Max) was 12.4 (range, 3.0-38.4). The mean differential tumor heterogeneity was -1.074 (range, -0.107 to -5.623). There was no association between dV/dT and SUVMax (R2 = 0.069), but there was a relationship with dV/dT and tumor volume (R2 = 0.881). There was no correlation of dV/dT with tumor histology (P = 0.4905). Heterogeneity was significantly associated with the risk of lymph node metastasis at diagnosis (P = 0.0009), tumor response to radiation as evaluated by FDG-PET obtained 3 months after completing treatment (P = 0.0207), risk of pelvic recurrence (P = 0.0017), and progression-free survival (P = 0.03).

CONCLUSIONS

Cervical intratumoral FDG metabolic heterogeneity on the pretreatment FDG-PET predicts risk of lymph node involvement at diagnosis, response to therapy, and risk of pelvic recurrence.

18-F-fluorodeoxyglucose-positron emission tomography evaluation of early metabolic response during radiation therapy for cervical cancer

PURPOSE

To document changes in cervical tumor (18)-F-fluorodeoxyglocose (FDG) uptake during radiation therapy and to correlate those changes with post-treatment tumor response and survival outcome.

METHODS AND MATERIALS

A total of 36 patients with Stage Ib1 to IIIb cervical cancer were enrolled in an institutional protocol examining the use of fluorodeoxyglucose-positron emission tomography (FDG-PET) for brachytherapy treatment planning. As part of this study, FDG-PET or PET/computed tomograpy (CT) images were obtained before, during, and after the completion of radiation therapy. Tumor metabolic responses were assessed qualitatively and semi-quantitatively by measurement of the maximal standardized uptake value (SUV(max)).

RESULTS

Post-treatment FDG-PET images were obtained for 36 patients in this study. Of the patients, 29 patients had a complete metabolic response on the post-treatment PET, 4 had a partial metabolic response, and 3 had new sites of FDG uptake. Six patients had a complete metabolic response observed during radiation therapy, 26 had a partial metabolic response and 4 had stable or increased tumor metabolic activity. For patients with complete metabolic response during radiation therapy, median time to complete response was 29.5 days (range, 18-43 days). The mean cervical tumor SUV(max) decreased from 11.2 (SD, 6.3; range, 2.1-38.0) pretreatment to 2.4 (SD, 2.7; range, 0-8.8) mid treatment, and 0.5 (SD, 1.7; range, 0-8.3) post-treatment.

CONCLUSIONS

During radiation therapy for cervical cancer, FDG-PET can be used to monitor treatment response. Complete metabolic response during radiation therapy was observed for a subset of patients. Recommendations regarding the optimal timing of FDG-PET during treatment for cervical cancer will require further systematic study.

Image-guided adaptive brachytherapy for cervix carcinoma

Sectional imaging has played an important role in the management of cervical cancer, in particular for staging, and is now considered for image-guided treatment planning, in particular for brachytherapy. Image-based three-dimensional brachytherapy is a relatively new approach that is increasingly replacing the traditional two-dimensional X-ray-based method. This overview focuses on the potential and some practicalities of this approach. The pros and cons of computed tomography- and magnetic resonance imaging-based brachytherapy are considered and an overview of the current state of research is given. The first encouraging clinical results are presented and future perspectives are discussed.

The standardized uptake value for F-18 fluorodeoxyglucose is a sensitive predictive biomarker for cervical cancer treatment response and survival

BACKGROUND

The objective of this study was to evaluate cervical tumor uptake of F-18 fluorodeoxyglucose (FDG) measured as the maximal standardized uptake value (SUV(max)) by positron emission tomography (PET) and its association with treatment response and prognosis in patients with cervical cancer.

METHODS

The study population consisted of 287 patients with stage IA2 through IVB cervical cancer who underwent pretreatment FDG-PET studies. SUV(max), tumor volume, and sites of lymph node metastasis were recorded. Therapy included surgery, chemoradiation, or palliation.

RESULTS

The mean SUV(max) was 11.4 (range, 1-50.4). The mean tumor volume by stage was 42.1 cm(3) for stage I tumors (using International Federation of Gynecology and Obstetrics [FIGO] staging criteria), 63.7 cm(3) for stage II tumors, 129.2 cm(3) for stage III tumors, and 166.2 cm(3) for stage IV tumors. There was no correlation between tumor volume and SUV(max) (correlation coefficient [R(2)] = 0.01). No significant difference in SUV(max) was observed between squamous histology (n = 247 patients) and nonsquamous histology (n = 40 patients; P = .089). Higher SUV(max) was associated with an increased risk of lymph node metastasis at diagnosis (P = .0009). A Cox proportional-hazards model for death from cervical cancer was used to evaluate tumor histology, lymph node metastasis, tumor volume, and SUV(max). The results indicated that SUV(max) was the only significant independent factor (P = .0027). Three prognostic groups were established using SUV(max). The overall survival rates at 5 years were 95% for an SUV(max) </= 5.2, 70% for an SUV(max) > 5.2 and </=13.3, and 44% for an SUV(max) > 13.3 (P < .0001). Increasing SUV(max) was associated with persistent abnormal FDG uptake in the cervix on 3-month FDG-PET studies in 238 patients who received curative chemoradiation (P = .04).

CONCLUSIONS

The SUV(max) of the cervical tumor at diagnosis was a sensitive biomarker of treatment response and prognosis for patients with cervical cancer.

FDG-PET/CT tumor segmentation-derived indices of metabolic activity to assess response to neoadjuvant therapy and progression-free survival in esophageal cancer: correlation with histopathology results

PURPOSE

To evaluate the diagnostic and prognostic abilities of PET tumor segmentation-derived indices of metabolic activity for the assessment of response to neoadjuvant chemoradiotherapy and progression-free survival in patients with esophageal cancer.

METHODS

Twenty-five patients with histologically confirmed esophageal cancer were retrospectively evaluated. The patients underwent PET-CT imaging before and after completion of neoadjuvant therapy. Images were evaluated visually and quantitatively with a three-dimensional threshold-based region-growing program, which calculates SUVm, SUVa of the entire tumor, metabolic tumor length (Lm) and volume (Vm) before and after therapy (SUVm1, SUVm2, SUVa1, SUVa2, Lm1, Lm2, Vm1, and Vm2, respectively). Percentage changes in these metabolic variables before and after therapy were also calculated (%SUVm, %SUVa, %Lm, %Vm, respectively).

RESULTS

SUVm1 (P = 0.018), SUVa1 (P = 0.019), Lm1 (P = 0.016), and Vm1 (P = 0.016) correlated with T-status. Advanced stage tumors (T3 + T4) had significantly higher glucose metabolism, metabolic length, and volume. Moreover, Lm1 >47.4 mm and Vm1 >29 cm3 were the best predictors of the level of tumor invasiveness. SUVm1 >12.7 and SUVa1 >5.9 could differentiate patients with positive lymph nodes from those without at presentation. %SUVa >32.3% and the SUVa1 >5.5 proved to be reliable predictors of pathologic response. SUVa2 >3.55 and SUVm2 >4.35 were the best predictors of disease progression during follow-up, with the latter having the best prognostic value.

CONCLUSIONS

This study showed that FDG-PET tumor segmentation-derived indices of metabolic activity play a definite role in the evaluation of response to neoadjuvant chemoradiotherapy and progression-free survival in patients with esophageal cancer.

Time trends in the maximal uptake of FDG on PET scan during thoracic radiotherapy. A prospective study in locally advanced non-small cell lung cancer (NSCLC) patients

BACKGROUND AND PURPOSE

18F-fluoro-2-deoxy-glucose (FDG) uptake on PET scan is a prognostic factor for outcome in NSCLC. We investigated changes in FDG uptake during fractionated radiotherapy in relation to metabolic response with the ultimate aim to adapt treatment according to early response.

METHODS AND MATERIALS

Twenty-three patients, medically inoperable or with advanced NSCLC, underwent four repeated PET-CT scans before, during and after radiotherapy. Changes in maximal standardized uptake value (SUVmax) were described. Patients were treated with accelerated radiotherapy with a total tumour-dose depending on normal tissue dose constraints.

RESULTS

The most striking result was the large intra-individual heterogeneity in the evolution of SUVmax. For the total group a non-significant increase in the first week (p=0.05), and a decrease in the second week (p=0.02) and after radiotherapy (p<0.01) was observed. Different time trends were shown for responders (no change during radiotherapy) and non-responders (48% increase during first week, p=0.02 and 15% decrease in the second week, p=0.04). Non-responders had a higher SUVmax on all time points investigated.

CONCLUSIONS

Time trends in SUVmax showed a large intra-individual heterogeneity and different patterns for metabolic responders and non-responders. These new findings may reflect intrinsic tumour characteristics and might finally be useful to adapt treatment.

Adaptive brachytherapy treatment planning for cervical cancer using FDG-PET

PURPOSE

A dosimetric study was conducted to compare intracavitary brachytherapy using both a conventional and a custom loading intended to cover a positron emission tomography (PET)-defined tumor volume in patients with cervix cancer.

METHODS AND MATERIALS

Eleven patients who underwent an [(18)F]-fluoro-deoxy-D-glucose (FDG)-PET in conjunction with their first, middle, or last brachytherapy treatment were included in this prospective study. A standard plan that delivers 6.5 Gy to point A under ideal conditions was compared with an optimized plan designed to conform the 6.5-Gy isodose surface to the PET defined volume.

RESULTS

A total of 31 intracavitary brachytherapy treatments in conjunction with an FDG-PET were performed. The percent coverage of the target isodose surface for the first implant with and without optimization was 73% and 68% (p = 0.21). The percent coverage of the target isodose surface for the mid/final implant was 83% and 70% (p = 0.02), respectively. The dose to point A was higher with the optimized plans for both the first implant (p = 0.02) and the mid/last implants (p = 0.008). The dose to 2 cm(3) and 5 cm(3) of both the bladder and rectum were not significantly different.

CONCLUSIONS

FDG-PET based treatment planning allowed for improved dose coverage of the tumor without significantly increasing the dose to the bladder and rectum.