Comparison of conventional and CT-based planning for intracavitary brachytherapy for cervical cancer: target volume coverage and organs at risk doses

Integration of Ultrasound in Image-Guided Adaptive Brachytherapy in Cancer of the Uterine Cervix

Cervical cancer continues to be a public health concern, as it remains the second most common cancer despite screening programs. It is the third most common cause of cancer-related death for women, and the majority of cases happen in developing nations. The standard treatment for locally advanced cervical cancer involves the use of external beam radiation therapy, along with concurrent chemotherapy, followed by an image-guided adaptive brachytherapy (IGABT) boost. The five-year relative survival rate for European women diagnosed with cervical cancer was 62% between 2000 and 2007. Updated cervical cancer treatment guidelines based on IGABT have been developed by the Gynecological working group, which is composed of the Group Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology. The therapeutic strategy makes use of three-dimensional imaging, which can be tailored to the target volume and at-risk organs through the use of computed tomography or magnetic resonance imaging. Under anaesthesia, the brachytherapy implantation is carried out. Ultrasonography is utilised to assess the depth of the uterine cavity and to facilitate the dilation of the uterine canal during the application insertion. In this study, we examine data from the international literature regarding the application of ultrasound in cervical cancer brachytherapy.

Clinical outcome after high dose rate intracavitary brachytherapy with traditional point 'A' dose prescription in locally advanced carcinoma of uterine cervix: dosimetric analysis from the perspective of computed tomography imaging-based 3-dimensional treatment planning

OBJECTIVE

To analyze tumour response and toxicity with respect to cumulative radiotherapy dose to target and organs at risk (OARs) with computed tomography (CT)-based image guided adaptive brachytherapy planning for locally advanced carcinoma cervix.

METHODS

Patients were treated with two-dimensional concurrent chemoradiotherapy to whole pelvis followed by intracavitary brachytherapy (ICBT) with dose prescription to point 'A'. CT image-based delineation of high-risk clinical target volume (HR-CTV), urinary bladder, rectum and sigmoid colon was done with generation of dose-volume histogram (DVH) data and optimization of doses to target and OARs. Follow up assessments were done for response of disease and toxicity with generation of data for statistical analysis.

RESULTS

One hundred thirty-six patients were enrolled in the study. Delineated volume of HR-CTV ranged from 20.9 to 37.1 mL, with median value of 30.2 mL. The equivalent dose in 2 Gy per fraction (EQD2) for point 'A' ranged from 71.31 to 79.75 Gy with median value of 75.1 Gy and EQD2 HR-CTV D90 ranged from 71.9 to 89.7 Gy with median value of 85.1 Gy. 69.2% of patients showed complete response and after median follow-up of 25 months, 50 patients remained disease free, of whom, 74.0% had received ≥85 Gy to HR-CTV D90 versus 26.0% receiving <85 Gy to HR-CTV D90.

CONCLUSION

s Amidst the unavailability of magnetic resonance imaging facilities in low middle income countries, incorporation of CT-image based treatment planning into routine practice for ICBT provides the scope to delineate volumes of target and OARs and to generate DVH data, which can prove to be a better surrogate for disease response and toxicity.

Prognostic significance of albumin and globulin levels in cervical cancer patients treated with chemoradiotherapy

OBJECTIVE

Albumin-globulin ratio or albumin-globulin score predict survival in many cancers, but there are few data on cervical cancer patients. This study examined whether pre-treatment albumin and globulin levels, as well as the albumin-globulin ratio and albumin-globulin score, can predict treatment outcomes in cervical cancer patients undergoing definitive chemoradiotherapy.

METHODS

A retrospective analysis of cervical cancer patients treated between January 2006 and July 2014 was performed. Receiver operating characteristic curves for serum albumin and globulin levels, as well as albumin-globulin ratio values, were generated in order to determine the cut-off values for these parameters and to predict their sensitivity and specificity for predicting recurrence and survival. Univariate and multivariate analyses were used to identify prognostic factors for overall survival and progression-free survival.

RESULTS

A total of 139 patients were included. The median follow-up time was 11.5 years. The 5- and 10-year overall survival rates were 54.7% and 39.3%, while the 5- and 10-year progression-free survival rates were 48.9% and 36.4%, respectively. The optimal cut-off points were 3.79 g/dL for albumin, 3.27 g/dL for globulin, and 1.56 for albumin-globulin ratio. In the univariate analysis, significant prognostic factors for overall survival and progression-free survival were albumin-globulin ratio, albumin-globulin score, patient age, International Federation of Gynecology and Obstetrics (FIGO) stage, tumor size, lymph node metastasis, and treatment response. Older age, advanced stage, low albumin-globulin ratio, albumin-globulin score of 2, and inadequate treatment response had poor overall survival and progression-free survival in multivariable analysis. However, serum albumin and globulin levels were not found to be a significantly predictive factor for survival. There was a significant correlation between albumin levels, globulin levels, tumor size, stage, lymph node metastasis, and treatment response.

CONCLUSIONS

Pre-treatment albumin-globulin ratio and albumin-globulin score are useful prognostic factors in patients with cervical squamous cell cancer treated with definitive chemoradiotherapy, and may be suitable biomarkers for predicting treatment outcomes.

The impact of serum albumin-to-alkaline phosphatase ratio in cervical cancer patients treated with definitive chemoradiotherapy

We retrospectively analysed the prognostic significance of serum albumin, alkaline phosphatase (ALP) and albumin to ALP ratio (AAPR) and other prognostic factors affecting the overall survival (OS) and progression-free survival (PFS) in 200 cervical cancer patients treated with definitive chemoradiotherapy (CRT). The prognostic factors for OS and DFS, in addition to the predictive factors of albumin, ALP and AAPR, were investigated. Older age, lymph node metastasis, non-complete response (CR) to treatment and low serum albumin levels emerged as predictors of poor OS and PFS in multivariate analysis. However, with a cut-off value of 0.51, AAPR was not a significant prognostic factor of survival in multivariable analysis. There were no significant differences in clinicopathological factors between patients with low and high AAPR, except for lymph node metastasis, where lymph node metastasis rate was significantly higher in patients with a low AAPR compared to those with a high AAPR. Patients with CR had a significantly higher serum albumin level and AAPR compared to patients without CR. The pre-treatment serum albumin level was independent predictive for survival; therefore, it could be a suitable biomarker to guide systemic therapy and predict patient outcomes. Impact StatementWhat is already known on this subject? Two major determinants of tumour progression are nutritional status and inflammation. The albumin-to-alkaline phosphatase ratio (AAPR), which was originally proposed as a marker for nutritional status and immune response, was recently discovered to be a prognostic factor for various cancer types. However, its utility in the treatment of cervical cancer has not been established.What do the results of this study add? Low serum albumin levels were associated with a significantly shorter OS and PFS in cervical cancer patients treated definitively with CRT. AAPR, on the other hand, was not a significant prognostic factor for survival with a cut-off value of 0.51. Regional lymph node metastasis was significantly more common in patients with a low AAPR than in those with a high AAPR.What are the implications of these findings for clinical practice and/or further research? Patients with multiple clinicopathological risk factors and low serum albumin levels had an increased risk of disease recurrence and a poorer prognosis, highlighting the importance of additional adjuvant treatment strategies in these patients. Due to the preliminary nature of our findings, additional research is required to corroborate them.

Long-term outcomes of cervical cancer patients with complete metabolic response after definitive chemoradiotherapy

OBJECTIVE

We investigated the importance of metabolic parameters measured with 18F-fluorodeoxyglucose positron-emission tomography integrated with computed tomography (FDG-PET/CT) for predicting progression-free survival (PFS) and overall survival (OS) in cervical cancer with complete metabolic response (CMR) after chemoradiotherapy (ChRT).

METHODS

The clinical data and PET parameters including standardized uptake value (SUV), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of 122 patients having CMR in post-treatment 18F-FDG-PET/CT delivered a median of 3.9 months after ChRT completion were analyzed.

RESULTS

With a median follow-up of 8.4 years, 55 patients (45%) presented with disease a median of 19.7 months after ChRT. For SUVp, MTVp, TLGp, SUVln, MTVln, and TLGp, the cut-off values for OS determined by receiver operating curve analysis were 15.8, 48.7 cm³, 552.3, 8.7, 7.0 cm³, respectively. All metabolic PET parameters were significant prognostic factors for OS and PFS in univariate analysis. International Federation of Gynecology and Obstetrics (FIGO) stage was predictive of both OS and PFS, while pelvic and/or para-aortic lymph node metastasis were predictive of OS only. In multivariate analysis, FIGO stage ≥IIB, MTVp ≥49.8 cm³, and TLGp ≥597.4 were predictive of worse OS. Advanced stage, presence of lymph node metastasis, higher TLGp, and larger MTVln were significant factors for poor PFS rates.

CONCLUSION

We found that advanced stage and higher TLGp values were significant predictors for poor survival and higher progression rates. Volumetric PET parameters could be used to predict treatment outcomes in patients with CMR after definitive ChRT.

Image-based 3D dosimetric studies with high dose rate intracavitary brachytherapy of cervical cancer

Aim:

To study 2D and 3D dosimetric values for bladder and rectum, and the influence of bladder volume on bladder dose in high dose rate (HDR) intracavitary brachytherapy (ICBT). The large patient data incorporated in this study would better represent the inherent variations in many parameters affecting dosimetry in HDR-ICBT.

Material and Methods:

We prospectively collected data for 103 consecutive cervical cancer patients (over 310 HDR fractions) undergoing CT-based HDR-ICBT at our centre. Correlation among bladder and rectum maximum volume doses and corresponding International Commission on Radiation Units and Measurement (ICRU) point doses were estimated and analysed. Impact of bladder volume on bladder maximum dose was assessed.

Results:

The ICRU point doses to bladder and rectum varied from the volumetric doses to these organs. Further, bladder volume poorly correlated with bladder maximum dose for volume variations encountered in the clinical practice at our centre.

Findings:

ICRU point doses to bladder and rectum are less likely to correlate with long-term toxicities to these organs. Further, in clinical practice where inter-fraction bladder volume does not vary widely there is no correlation between bladder volume and bladder dose.

Evaluation of Volumetric Doses of Organs at Risk in Carcinoma Cervix Patients with HDR Intracavitary Brachytherapy and Comparison of CT-based and Conventional Plans

Background:

Brachytherapy treatment planning in cervix carcinoma patients using two dimensional (2D) orthogonal images provides only point dose estimates while CT-based planning provides volumetric dose assessment helping in understanding the correlation between morbidity and the dose to organs at risk (OARs) and treatment volume.

Objective:

Aim of present study is to compare International Commission on Radiation Units and Measurements Report 38 (ICRU 38) reference point doses to OARs with volumetric doses using 2D images and CT images in patients with cervical cancer.

Material and Methods:

In this prospective study, 20 patients with cervical cancer stages (IIB-IIIB) were planned for a brachytherapy dose of 7Gy per fraction for three fractions using 2D image-based treatment plan and CT-based plan. ICRU 38 points for bladder and rectum were identified on both 2D image-based plan and CT-based plan and doses (D_ICRU) at these points were compared to the minimum dose to 2cc volume (D_2cc) of bladder and rectum receiving the highest dose.

Results:

D_2cc bladder dose was 1.60 (±0.67) times more than D_ICRUb bladder dose whereas D_2cc rectum dose was 1.13±0.40 times D_ICRUr. Significant difference was found between D_ICRUb and D_2cc dose for bladder (p=.0.016) while no significant difference was seen between D_ICRUr and D_2cc dose for rectum (p=0.964).

Conclusion:

The study suggests that ICRU 38 point doses are not the true representation of maximum doses to OARs. CT-based treatment planning is more a reliable tool for OAR dose assessment than the conventional 2D radiograph-based plan.

The prognostic value of haematologic parameter changes during treatment in cervical cancer patients treated with definitive chemoradiotherapy

We retrospectively analysed the prognostic significance of changes in absolute neutrophil count (ANC), absolute lymphocyte count (ALC) and neutrophil/lymphocyte ratio (NLR) during treatment with definitive chemoradiotherapy (CRT) in 104 cervical cancer patients. The absolute white blood cell, ANC and ALC decrease during treatment, NLR increased throughout treatment and reached to a plateau at fifth week. The ANC and NLR after 3rd week of definitive CRT were significantly higher and ALC after 3rd week of treatment was significantly lower in patients with progressive disease compared patients with no evidence of disease. Patients in low-haematological risk (LHR) group had significantly higher number of patients with smaller tumour size, early stage disease and without lymph node metastasis. In multivariate analysis, high-haematological risk (HHR) group and lymph node metastasis were negative prognosticators of overall and disease-free survival (DFS). The presence of lymph node metastasis and HHR could serve as a predicative factor of poor prognosis for cervical cancer patients. IMPACT STATEMENT What is already known on this subject? The ANC and NLR after 3rd week of definitive CRT were significantly higher and ALC after 3rd week of treatment was significantly lower in patients with progressive disease compared patients with no evidence of disease. Patients in LHR group had significantly higher number of patients with smaller tumour size, early stage disease and without lymph node metastasis. Lymph node metastasis and HHR and were negative prognosticators of overall and disease-free survival (DFS). The presence of lymph node metastasis and HHR could serve as a predicative factor of poor prognosis for cervical cancer patients. What the results of this study add? Weekly changes in ANC, ALC, and NLR, especially after 3rd week of treatment are predictive factors of disease progression, not the high-risk features of disease. Furthermore, in HHR group more patients with extensive stage disease, larger tumour and lymph node metastasis were observed compared to LHR group. What the implications are of these findings for clinical practice and/or further research? The patients may be stratified according to risk factors. The treatment intensification maybe required for HHR patients compared to LHR patients. Since our findings are preliminary, further studies are required to support these findings.

Evaluation of variation of interfraction doses to organs at risk during brachytherapy of cervical cancer

Background

Two-dimensional treatment planning using radiographs or simulator films was the standard in planning brachytherapy for patients with cervical cancer. Three-dimensional (3D) treatment planning has improved treatment efficacy. This retrospective study compares conventional and 3D treatment planning of brachytherapy in patients with cervical cancer and interfraction dose variation to bladder and rectum (D2cc).

Methods

The mean doses to bladder and rectum (D2cc) were computed by computed tomography (CT)-based planning during 100 sessions of intracavitary brachytherapy for carcinoma cervix with the same source configuration as generated for conventional planning, and these estimates were compared with the doses at International Commission on Radiation Units and measurements (ICRU) rectal, bladder points and point A. Interfraction variation of doses to bladder and rectum during various sessions was also analysed.

Result

The mean ICRU bladder dose and D2cc of the bladder for all patients was 3.7 Gy and 7.4 Gy, respectively (p < 0.001). The mean ICRU rectal dose from conventional plan was 4.3Gy and with CT planning, 4.45 Gy (p = 0.04). Interfraction dose variations for D2cc of the bladder were min -5.3 Gy and max 4.8 Gy and those of the rectum were min -1.8 Gy and max 1.72Gy.

Conclusion

Dosimetric evaluation of conventional and 3D CT-based treatment planning for the same brachytherapy sessions demonstrated underestimation of ICRU bladder dose points (p < 0.001) and the rectal ICRU point dose and D2cc (p=0.04). The doses to organs at risk did not show a statistically significant variation between the fractions. However, large variation was noted between the interfractional maximum and minimum doses to bladder and rectum.

Prognostic values of ADCmean and SUVmax of the primary tumour in cervical cancer patients treated with definitive chemoradiotherapy

We analysed the correlation of 18F-fluorodeoxyglucose uptake into primary tumours using the maximum standardised uptake value (SUVmax) and the mean apparent diffusion coefficient (ADCmean) values in magnetic resonance imaging (MRI) with the clinical and pathological factors in patients with cervical cancer who were treated with concurrent chemoradiotherapy. The patients were stratified according to the primary tumour pre-treatment ADCmean and SUVmax cut-off values. There were significant correlations between the SUVmax of the primary tumour and tumour size, and the treatment response. The correlation between the ADCmean and FIGO stage, tumour size, and the lymph node metastasis was significant. The SUVmax was significantly and inversely correlated with the ADCmean for cervical cancer (r = -0.44, p <.001). In the multivariate analysis, the primary tumour ADCmean, treatment response and the lymph node metastasis emerged as significant independent predictors of both OS and DFS, and of the primary tumour SUVmax for DFS. Tumour size has a borderline significance for OS. High SUVmax and low ADCmean of the primary tumour are important predictive factors for identifying high-risk patients with cervical cancer who are treated with definitive chemoradiotherapy. These results point to a future role for the diffusion-weighted MRI and for 18F-fluorodeoxyglucose positron emission tomography, not only in the staging of cervical cancer but as an aid in the selection of an adjuvant treatment regimen after chemoradiotherapy for individual patients. Impact statement What is already known on this subject? A negative correlation between primary tumour SUVmax derived from positron emission tomography (PET/CT) and ADCmin derived from diffusion weighted magnetic resonance imaging (DW-MRI) in various cancer types and cervical cancer has been demonstrated. However, the prognostic value of primary tumour SUVmax and ADCmean in cervical cancer patients treated with definitive chemoradiotherapy is not well studied yet. What the results of this study add? The patients with high-risk features (larger tumours, extensive stage, lymph node metastasis) had higher primary tumour SUVmax and lower ADCmean values. Primary tumour ADCmean and lymph node metastasis emerged as significant independent predictors of both overall and disease-free survival. This study demonstrated that the functional biomarkers delivered from PET-CT and DW-MRI are important in predicting the treatment outcomes in the squamous cell carcinoma of cervix treated with definitive chemoradiotherapy, where clinical and radiological findings are very important, since these patients are not staged surgically. What are the implications of these findings for clinical practice and/or further research? Based on these findings, there may be a future role of DW-MRI and FDG/PET-CT not only in the staging of cervical cancer but as an aid in the selection of an adjuvant treatment regimen after chemoradiotherapy (ChRT) for individual patients.

A dosimetric comparison of Volumetric Modulated Arc Therapy (VMAT) and High Dose Rate (HDR) brachytherapy in localized cervical cancer radiotherapy

BACKGROUND

Cervical cancer radiotherapy is usually administrated through 3-Dimensional Conformal Radiation Therapy (3DCRT) followed by a brachytherapy (BT) boost.

PURPOSE

To investigate whether Volumetric Modulated Arc Therapy (VMAT) can replace High Dose Rate (HDR) intracavitary BT boost for patients undergoing cervical cancer radiotherapy.

MATERIALS AND METHODS

Computed Tomography (CT) images for ten patients with tandem and ovoids were included in this study. Target volumes, rectum, bladder, sigmoid, small bowel and both femoral heads were delineated. Two plans were carried out including (a) a BT plan optimized manually by modifying dwell time and Ir-192 source positions, (b) a VMAT plan generated using two partial arcs with 10 MV photon beam. The prescribed dose was 7 Gy. The relevant dose volume parameters (DVPs) of target volumes and OARs for the two plans were analyzed statistically using SPSS Wilcoxon Signed Rank test.

RESULTS

VMAT plan showed a significant reduction of 9.1%, 9.3%, 15.4%, 14.4% and 13.1% in rectum maximum dose, rectum D2cc, bladder maximum dose, bladder D2cc and sigmoid maximum dose (P < 0.05). VMAT and BT plans showed comparable D2cc of sigmoid and small bowel maximum doses (P = 0.333 and P = 0.646). On the other hand, VMAT showed significantly higher small bowel D2cc and maximum point dose for both femoral heads comparing to BT plan (P < 0.05). Also, VMAT plan yielded greater homogeneous target coverage compared to BT plan (P < 0.05).

CONCLUSION

The study demonstrated that VMAT plan achieves significant dose reduction of rectum, bladder and sigmoid, as well as superior homogeneous target coverage compared to BT plan. On the other hand, VMAT delivers more radiation exposures to small bowel and femoral heads.

The Utility of Pretreatment and Posttreatment Lymphopenia in Cervical Squamous Cell Carcinoma Patients Treated With Definitive Chemoradiotherapy

OBJECTIVE

The aim of this study was to investigate the prognostic significance of pretreatment and posttreatment lymphopenia in locally advanced squamous cell carcinoma (SCC) cervical cancer patients treated with definitive chemoradiotherapy (ChRT).

METHODS

Data from 95 patients with SCC were retrospectively analyzed. Relationships between pretreatment or posttreatment lymphopenia and patient or tumor characteristics, and overall survival (OS) and disease-free survival (DFS) were evaluated.

RESULTS

Median follow-ups for the entire cohort and survivors were 68 months (range, 3-133 months) and 88 months (range, 22-133 months), respectively. Ten patients (11%) exhibited pretreatment lymphopenia, whereas 58 patients (61%) exhibited posttreatment lymphopenia. Median pretreatment total lymphocyte counts decreased from 2029 cells/μL to 506 cells/μL 2 months after ChRT (P < 0.001). The 5-year OS and DFS rates were significantly higher in patients without pretreatment lymphopenia compared with patients with pre-retreatment lymphopenia (61% vs 20% [P < 0.001], 55% vs 20% [P < 0.001]). Patients without posttreatment lymphopenia had significantly higher 5-year OS and DFS rates than their counterparts (70% vs 46% [P = 0.02], 70% vs 39% [P = 0.004]). Complete response (CR) was observed in significantly fewer patients with pretreatment lymphopenia than in those without, after ChRT. Patients with posttreatment lymphopenia had higher rates of lymph node metastasis (P = 0.001) and lower posttreatment CR rates (P = 0.01) versus patients without posttreatment lymphopenia. In univariate analysis, International Federation of Gynecology and Obstetrics stage, tumor size, lymph node metastasis, and treatment response were prognostic for OS and DFS. In multivariate analysis, pretreatment lymphopenia, lymph node metastasis, and treatment response were independent predictors of OS and DFS. Age was predictive of OS. Tumor size was prognostic for DFS.

CONCLUSIONS

Pretreatment lymphopenia and posttreatment lymphopenia are associated with worse treatment response in patients given ChRT for cervical SCC. Pretreatment lymphopenia is predictive for OS and DFS. Therapeutic strategies including pretreatment or posttreatment immune preservation or modulation may improve response rates and survival in women with cervical SCC.

Dosimetric evaluation of Point A and volume-based high-dose-rate plans: a single institution study on adaptive brachytherapy planning for cervical cancer

Purpose

External beam radiation therapy (EBRT) and brachytherapy (BT) with concurrent cisplatin is the standard of care for locally advanced cervical cancer. The applicability of image-guided adaptive volume-based high-dose-rate (HDR) intracavitary brachytherapy planning is an active area of investigation. In this study, we examined whether volume-based HDR-BT (HDR_VOL) plans leads to more conformal plans compared to Point A (HDR_PointA)-based plans.

Material and methods

Two hundred and forty HDR_PointA plans from 48 cervical cancer patients treated with chemoradiotherapy were retrospectively collected. Point A plans were renormalized with respect to the high-risk clinical target volume (HR-CTV) for the HDR_VOL plans. The doses to organs at risk (OAR; rectum, sigmoid, and bladder), and HR-CTV and the conformal index were compared between HDR_PointA and HDR_VOL plans.

Results

HDR_VOL plans resulted in a 6-12% reduction in the total dose (EBRT + HDR-BT) to 0.1 cc, 1.0 cc, and 2.0 cc of the OAR as well as an 8-37% reduction in the dose to 2 cc of OAR per HDR-BT fraction compared to HDR_PointA plans. Differences in the conformal indexes between the two groups of plans showed an 18-31% relative increase per HDR-BT fraction for HDR_VOL plans. The D₉₀ of the HR-CTV was reduced by 11% by HDR_VOL planning and had a median dose of 86 Gy.

Conclusions

Our study reports the relative improvement in OAR doses per HDR-BT fraction by HDR_VOL planning compared to HDR_PointA planning and demonstrates the dosimetric advantages of volume-based HDR-BT planning in creating more conformal plans.

Pretreatment metabolic tumour volume and total lesion glycolysis are not independent prognosticators for locally advanced cervical cancer patients treated with chemoradiotherapy

OBJECTIVE

To evaluate the prognostic significance of metabolic parameters derived from fludeoxyglucose (FDG) positron emission tomography (PET)/CT, in cervical cancer patients treated with concurrent chemoradiotherapy.

METHODS

We retrospectively reviewed medical records from 129 biopsy-proven non-metastatic cervical cancer patients treated with external radiotherapy and intracavitary brachytherapy at our department. Correlation between metabolic parameters and tumour characteristics was evaluated. Prognostic factors for survival, local control and distant metastasis were analysed.

RESULTS

The median follow up for all patients and surviving patients was 30.0 months (range, 3.7-94.7 months) and 50.5 months (range, 14.5-94.7 months), respectively. The 2- and 5-year overall survival (OS) and disease-free survival (DFS) rates were 68 42, 54 and 38%, respectively. The maximum standardized uptake value (SUVmax), SUVmean, metabolic tumour volume (MTV) and total lesion glycolysis were significantly higher in patients with larger tumours (>4 cm) and partial regression or progressive disease after definitive treatment compared to patients with smaller tumour (≤4 cm) and post-treatment complete response. On univariate analysis, stage, lymph node metastasis, tumour size >4 cm, SUVmax, MTV, SUVmean and total lesion glycolysis were prognostic factors for OS and DFS. On multivariate analysis, only larger tumour and presence of lymph node metastasis were significant prognostic factors for both OS and DFS. Additionally, extensive stage was a significant prognosticator for DFS.

CONCLUSION

Although, metabolic parameters derived from FDG-PET/CT had a prognostic significance in univariate analysis, the significance was lost in multivariate analysis where tumour stage, size and lymph node status were the only independent parameters. Advances in knowledge: The clinical benefit of using FDG-PET/CT metabolic parameters to evaluate the high-risk patients among cervical cancer patients and to eventually change patient management still needs further clarification.

Predicting tumor recurrence in patients with cervical carcinoma treated with definitive chemoradiotherapy: value of quantitative histogram analysis on diffusion-weighted MR images

Background Further research is required for evaluating the use of ADC histogram analysis in more advanced stages of cervical cancer treated with definitive chemoradiotherapy (CRT). Purpose To investigate the utility of apparent diffusion coefficient (ADC) histogram derived from diffusion-weighted magnetic resonance images in cervical cancer patients treated with definitive CRT. Material and Methods The clinical and radiological data of 50 patients with histologically proven cervical squamous cell carcinoma treated with definitive CRT were retrospectively analyzed. The impact of clinicopathological factors and ADC histogram parameters on prognostic factors and treatment outcomes was assessed. Results The mean and median ADC values for the cohort were 1.043 ± 0.135 × 10-3 mm2/s and 1.018 × 10-3 mm2/s (range, 0.787-1.443 × 10-3 mm2/s). The mean ADC was significantly lower for patients with advanced stage (≥IIB) or lymph node metastasis compared with patients with stage Collapse

Key Words

• Cervical cancer
• apparent diffusion coefficient
• chemoradiotherapy
• magnetic resonance imaging (MRI)
• prognostic factor

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MESH Headings

• Adult
• Aged
• Aged, 80 and over
• Cervix Uteri/diagnostic imaging
• Chemoradiotherapy/methods
• Diffusion Magnetic Resonance Imaging/methods
• Disease-Free Survival
• Female
• Follow-Up Studies
• Humans
• Image Interpretation, Computer-Assisted/methods
• Middle Aged
• Neoplasm Recurrence, Local/diagnostic imaging
• Reproducibility of Results
• Retrospective Studies
• Treatment Outcome
• Uterine Cervical Neoplasms/diagnostic imaging
• Uterine Cervical Neoplasms/therapy
• Young Adult

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Affiliation(s)

Gurcan Erbay 1 Department of Radiology, Baskent University Faculty of Medicine, Ankara, Turkey
Cem Onal 2 Department of Radiation Oncology, Baskent University Faculty of Medicine, Adana, Turkey
Elif Karadeli 1 Department of Radiology, Baskent University Faculty of Medicine, Ankara, Turkey
Ozan C Guler 2 Department of Radiation Oncology, Baskent University Faculty of Medicine, Adana, Turkey
Sami Arica 3 Department of Electrical and Electronics Engineering, Cukurova University Faculty of Engineering and Architecture, Adana, Turkey
Zafer Koc 1 Department of Radiology, Baskent University Faculty of Medicine, Ankara, Turkey

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Treatment response evaluation using the mean apparent diffusion coefficient in cervical cancer patients treated with definitive chemoradiotherapy

PURPOSE

To investigate the pre- and posttreatment mean apparent diffusion coefficient (ADCmean ) of cervical cancer tumors treated with definitive chemoradiotherapy (CRT) and evaluate their correlation with recurrence and survival rates.

MATERIALS AND METHODS

Forty-four patients with cervical squamous cell carcinoma were retrospectively evaluated. All patients underwent multiparametric 1.5T magnetic resonance imaging (MRI) including T2 -weighted, fat-saturated T2 -weighted, dynamic contrast-enhanced (DCE), and diffusion-weighted imaging (DWI) sequences before and after treatment. Posttreatment MR images were acquired within a median of 3.2 months (range, 2.8-4.1 months) after completing CRT. We assessed the impact of primary tumor pre- and posttreatment ADC values on prognostic factors and treatment outcomes.

RESULTS

The pre- and posttreatment ADCmean values were 0.882 ± 0.096 × 10(-3) mm(2) /sec and 1.159 ± 0.168 × 10(-3) mm(2) /sec, respectively, and the difference was statistically significant (P < 0.001). The median percent ADC change was 33.7% (range, 5.0-70.0%). Patients with disease recurrence had lower ADC values, both pretreatment (0.822 ± 0.096 × 10(-3) mm(2) /sec vs. 0.936 ± 0.058 × 10(-3) mm(2) /sec; P < 0.001) and posttreatment (1.060 ± 0.116 × 10(-3) mm(2) /sec vs. 1.248 ± 0.160 × 10(-3) mm(2) /sec; P < 0.001). The ADC change was lower in patients with recurrence (25.7% ± 13.0% vs. 42.8% ± 15.7; P < 0.001) than in patients without recurrence. In multivariate analysis, pelvic lymph node metastasis and pretreatment ADCmean were prognostic factors for overall survival (OS) and disease-free survival (DFS). ADC change between pre- and posttreatment DW-MRI was a prognostic factor for OS.

CONCLUSION

DWI parameters, measured before and after treatment, may be useful prognostic biomarkers for tumor burden, recurrence, and survival in cervical cancer patients treated with CRT. The primary tumor pretreatment ADCmean is an independent prognostic factor for DFS and OS. J. MAGN. RESON. IMAGING 2016;44:1010-1019.

Dosimetric Comparison between Three-Dimensional Magnetic Resonance Imaging-Guided and Conventional Two-Dimensional Point A-Based Intracavitary Brachytherapy Planning for Cervical Cancer

OBJECTIVE

The purpose of this study was to comprehensively compare the 3-dimensional (3D) magnetic resonance imaging (MRI)-guided and conventional 2-dimensional (2D) point A-based intracavitary brachytherapy (BT) planning for cervical cancer with regard to target dose coverage and dosages to adjacent organs-at risk (OARs).

METHODS

A total of 79 patients with cervical cancer were enrolled to receive 2D point A-based BT planning and then immediately to receive 3D planning between October 2011 and April 2013 at the First Hospital Affiliated to Xi'an Jiao Tong University (Xi'an, China). The dose-volume histogram (DVH) parameters for gross tumor volume (GTV), high-risk clinical target volume (HR-CTV), intermediate-risk clinical target volume (IR-CTV) and OARs were compared between the 2D and 3D planning.

RESULTS

In small tumors, there was no significant difference in most of the DVHs between 2D and 3D planning (all p>0.05). While in big tumors, 3D BT planning significantly increased the DVHs for most of the GTV, HR-CTV and IR-CTV, and some OARs compared with 2D planning (all P<0.05). In 3D planning, DVHs for GTV, HR-CTV, IR-CTV and some OARs were significantly higher in big tumors than in small tumors (all p<0.05). In contrast, in 2D planning, DVHs for almost all of the HR-CTV and IR-CTV were significantly lower in big tumors (all p<0.05). In eccentric tumors, 3D planning significantly increased dose coverage but decreased dosages to OARs compared with 2D planning (p<0.05). In tumors invading adjacent tissues, the target dose coverage in 3D planning was generally significantly higher than in 2D planning (P<0.05); the dosages to the adjacent rectum and bladder were significantly higher but those to sigmoid colon were lower in 3D planning (all P<0.05).

CONCLUSIONS

3D MRI image-guided BT planning exhibits advantages over 2D planning in a complex way, generally showing advantages for the treatment of cervical cancer except small tumors.

Prognostic Use of Pretreatment Hematologic Parameters in Patients Receiving Definitive Chemoradiotherapy for Cervical Cancer

OBJECTIVES

The aim of this work was to evaluate the prognostic role of pretreatment neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in recipients of definitive chemoradiotherapy (ChRT) for cervical cancer.

METHODS

In 235 patients given definitive ChRT for histologically confirmed cervical cancer, clinical data and pretreatment complete blood cell counts were analyzed. Prognostic and therapeutic ramifications of NLR and PLR were assessed.

RESULTS

Median pretreatment NLR and PLR were 3.03 (range, 1.04-13.03) and 133.02 (range, 36.3-518.16), respectively. Both NLR and PLR correlated significantly with tumor size, lymph node metastasis, and treatment response. In addition to NLR and PLR, tumor stage, size, and nodal metastasis were identified by univariate analysis as significant predictors of overall survival (OS) and progression-free survival (PFS). By multivariate analysis, independent predictors of OS and PFS were NLR (OS: hazard ratio [HR], 3.322; 95% confidence interval [CI], 1.905-5.790; PFS: HR, 3.579; 95% CI, 2.106-6.082; both P < 0.001) and lymph node metastasis (OS: HR, 2.620; 95% CI, 1.706-4.023; PFS: HR, 2.989; 95% CI, 1.918-4.378; both P < 0.001), although patients' age (HR, 1.019; 95% CI, 1.003-1.035; P = 0.02) was also significantly predictive of OS.

CONCLUSIONS

Pretreatment NLR and PLR were associated with larger tumors, lymph node metastasis, and poorer therapeutic responses to definitive ChRT. By multivariate analysis, pretreatment NLR and lymph node metastasis were found independently predictive of OS and PFS, whereas patients' age was significantly predictive of OS only. In patients with advanced cervical cancer, NLR is a potential biomarker, serving to guide systemic therapy and predict treatment outcomes.

Late rectal toxicity determined by dose-volume parameters in computed tomography-based brachytherapy for locally advanced cervical cancer

The aim of this study was to observe the relationship between dose–volume histogram (DVH) parameters and rectal late side effects (LSE) in computed tomography (CT)‐based brachytherapy (BT) for patients with locally advanced cervical cancer. In total, 144 cervical cancer patients received external beam radiotherapy and CT‐based BT. The data from 111 survival cases with pelvic local control (LC) were used to analyze the relationship between DVH parameters and rectal LSE. The total doses, manifesting 2, 1, and 0.1 cm³ (D_2cc, D_1cc, and D_0.1cc) of the rectum, and D₉₀ for high‐risk clinical target volume (HR CTV) were computed and normalized to 2 Gy fractions (EQD2) using a linear‐quadratic model. The rectal LSE were evaluated by the late effects in normal tissues‐subjective, objective, management, and analytic (LENT‐SOMA) scale. A dose–response relationship was evaluated by probit analyses. For all patients, the total rate of rectal LSE was 56%, and the rate of ≥Grade 2 LSE was 27.4%. For the 111 survival cases with pelvic LC, the total mean for D_2cc was 71.23 ± 5.54 Gy for the rectum, and the D_2cc, D_1cc, and D_0.1cc values for Grades 2 and 3 were higher than those for Grades 0 and 1. In addition, the number of complications increased, and the complications became more severe as the dose increased, with a dose of 73.5 Gy resulting in a 10% probability of ≥Grade 3 LSE. In conclusion, DVH parameters could predict the incidence and grades of rectal LSE in CT‐based BT. D_2cc showed an excellent predictive value, and 73.5 Gy for D_2cc of the rectum might be considered as an alternative dose limit.

Prognostic value of 18F-fluorodeoxyglucose uptake in pelvic lymph nodes in patients with cervical cancer treated with definitive chemoradiotherapy

PURPOSE

To evaluate the prognostic significance of the maximum standardized uptake (SUVmax) value for pelvic lymph nodes in patients with cervical cancer and its impact on treatment response, disease control, and survival.

METHODS

Ninety-three patients with pelvic or para-aortic metastasis detected by PET/CT and treated with definitive chemoradiotherapy were evaluated. The impact of pelvic lymph node SUVmax on prognostic factors and treatment outcomes was assessed.

RESULTS

The size and SUVmax of pelvic lymph nodes were significantly correlated (r=0.859; p<0.001). Patients with pelvic and para-aortic lymph node metastases had significantly higher SUVmax values for both primary tumor (23.4±9.2 vs. 18.5±7.3; p=0.01) and pelvic lymph nodes (11.4±4.6 vs. 7.4±3.8; p=0.001). Patients with pelvic lymph node SUVmax≥7.5 had significantly higher primary tumor SUVmax, larger pelvic lymph nodes, higher rates of para-aortic lymph node metastasis, and lower post-therapy complete response rates. Overall survival (OS) and disease-free survival (DFS) rates were significantly higher in patients with SUVmax<7.5 compared to patients with SUVmax≥7.5. In a multivariate analysis, pelvic lymph node SUVmax and post-therapy metabolic response were significant prognostic factors for both OS and DFS for all patients, but no significant prognostic factors were found in pelvic lymph node metastasis only.

CONCLUSIONS

Patients with highly FDG-avid pelvic lymph nodes have a higher risk of disease recurrence with worse survival. Identification of these patients may assist in the evaluation of the clinical benefits of additional treatments.

Effects of bladder distension on dose distribution of vaginal vault brachytherapy in patients with endometrial cancer

PURPOSE

To investigate dosimetric effects of bladder distention on organs at risk (OARs) during treatment of endometrial cancer using 3D image-based planning of postoperative vaginal vault brachytherapy (BRT).

MATERIAL AND METHODS

Fifteen patients with early-stage endometrial cancer were studied, each undergoing adjuvant BRT of vaginal vault via 3.5 cm diameter cylinder. As treatment, 25 Gy in 5 fractions were delivered to 5 mm depth of the vaginal mucosa. Dose-volume histograms of OARs were generated individually with bladder empty and with bladder inflated by sterile saline (180 ml), to compare doses received.

RESULTS

Bladder distention appreciably impacted dosimetry of bladder, sigmoid colon, and small bowel, but dosimetry of rectum was unaffected. With bladder inflated, mean cylinder-to-bowel distance increased significantly (1.69 cm vs. 1.20 cm; p = 0.006). Mean minimum dose to most exposed 2 cc (D2cc) volume also rose significantly at bladder (5.40 Gy vs. 4.55 Gy [18.7%]; p < 0.001), as opposed to near-significant reductions in D2cc at sigmoid colon (15.1%; p = 0.11) and at small bowel (10.5%; p = 0.14). A full bladder had no effect on dose to 50% volume (D50%) of bladder or rectum, and declines seen in mean D50% values of sigmoid colon (22.7%; p = 0.12) and small bowel (19.0%; p = 0.13) again fell short of statistical significance.

CONCLUSIONS

The combination of a full bladder and an empty rectum may cause significant unwanted increases in BRT dosing of bladder, without significantly impacting sigmoid colon and small bowel exposures. These findings should be validated through further clinical studies.

Image-based brachytherapy for cervical cancer

Cervical cancer is the third most common cancer in women worldwide; definitive radiation therapy and concurrent chemotherapy is the accepted standard of care for patients with node positive or locally advanced tumors > 4 cm. Brachytherapy is an important part of definitive radiotherapy shown to improve overall survival. While results for two-dimensional X-ray based brachytherapy have been good in terms of local control especially for early stage disease, unexplained toxicities and treatment failures remain. Improvements in brachytherapy planning have more recently paved the way for three-dimensional image-based brachytherapy with volumetric optimization which increases tumor control, reduces toxicity, and helps predict outcomes. Advantages of image-based brachytherapy include: improved tumor coverage (especially for large volume disease), decreased dose to critical organs (especially for small cervix), confirmation of applicator placement, and accounting for sigmoid colon dose. A number of modalities for image-based brachytherapy have emerged including: magnetic resonance imaging (MRI), computed tomography (CT), CT-MRI hybrid, and ultrasound with respective benefits and outcomes data. For practical application of image-based brachytherapy the Groupe Europeen de Curietherapie-European Society for Therapeutic Radiology and Oncology Working Group and American Brachytherapy Society working group guideline serve as invaluable tools, additionally here-in we outline our institutional clinical integration of these guidelines. While the body of literature supporting image-based brachytherapy continues to evolve a number of uncertainties and challenges remain including: applicator reconstruction, increasing resource/cost demands, mobile four-dimensional targets and organs-at-risk, and accurate contouring of “grey zones” to avoid marginal miss. Ongoing studies, including the prospective EMBRACE (an international study of MRI-guided brachytherapy in locally advanced cervical cancer) trial, along with continued improvements in imaging, contouring, quality assurance, physics, and brachytherapy delivery promise to perpetuate the advancement of image-based brachytherapy to optimize outcomes for cervical cancer patients.

Treatment outcomes of patients with cervical cancer with complete metabolic responses after definitive chemoradiotherapy

PURPOSE

We sought to evaluate failure patterns and prognostic factors predictive of recurrences and survival in cervical cancer patients who are treated with definitive chemoradiotherapy (ChRT), who have a subsequent complete metabolic response (CMR) with (18) F-fluorodeoxyglucose positron-emission tomography (FDG-PET) after treatment.

METHODS

The records of 152 cervical cancer patients who were treated with definitive chemoradiotherapy were evaluated. All patients underwent pre-treatment positron emission tomography (PET-CT), and post-treatment PET-CT was performed within a median of 3.9 months (range, 3.0-9.8 months) after the completion of ChRT. The prognoses of partial response/progressive disease (PR/PD) cases (30 patients, 18 %) and CMR cases (122 patients, %82) were evaluated. Univariate and multivariate analysis effecting the treatment outcome was performed in CMR cases.

RESULTS

The median follow-ups for all patients and surviving patients were 28.7 (range, 3.3-78.7 months) and 33.2 months (range, 6.23-78.7 months), respectively. Four-year overall survival (OS) rate was significantly better in patients with CMR compared to patients with PR/PD (66.9 % vs. 12.4 %, p < 0.001, respectively). Patients with PR/PD had higher maximum standardized uptake value (SUVmax) of primary cervical tumor (26.4 ± 10.1 vs. 15.9 ± 6.3; p < 0.001) and larger tumor (6.4 cm ± 2.3 cm vs. 5.0 cm ± 1.4 cm; p < 0.001) compared to patients with CMR. Of the 122 patients with post-treatment CMRs, 25 (21 %) developed local, locoregional, or distant failure. In univariate analysis, tumor size ≥ 5 cm, 'International Federation of Obstetricians and Gynecologists' (FIGO) stage ≥ IIB, and pelvic and/or para-aortic lymph node metastasis were predictive of both overall survival (OS) and disease-free survival (DFS), while histology was predictive of only OS. In multivariate analysis, tumor size, stage and lymph node metastasis were predictive of OS and DFS.

CONCLUSION

Although CMR is associated with better outcomes, relapses remain problematic, especially in patients with bulky tumors (≥ 5 cm), extensive stage (≥ IIB) or pelvic and/or para-aortic lymph node metastasis. These findings could support the need for more aggressive treatment or adjuvant chemotherapy regimens.

Uterine perforation during 3-dimensional image-guided brachytherapy in patients with cervical cancer: Baskent University experience

OBJECTIVES

This study aimed to determine the incidence and characteristics of uterine perforation at our department using 3-dimensional computed tomography (CT)-based brachytherapy (BRT). The characteristics of the patients presenting with perforation and impact of the perforation on the treatment course were also analyzed.

MATERIALS AND METHODS

The clinical and radiologic data of 200 patients with biopsy-proven cervical cancer treated using CT-based BRT were retrospectively evaluated. All patients had undergone tandem-based intracavitary BRT, and 67 patients had undergone magnetic resonance imaging (MRI) before BRT.

RESULTS

Of the 200 patients, 17 (8.5%) had uterine perforation. Of the 626 applications with CT images, 30 (4.8%) resulted in uterine perforation. The median age of patients with perforation was higher (68 years; range, 44-89 years) than that of the patients without perforation (59 years; range, 21-87 years), and the mean (SD) tumor size at diagnosis was larger in patients with perforation (7.0 [1.5] cm) than in patients without perforation (5.0 [1.5] cm). The most frequent perforation site was the posterior uterine wall (8 patients), followed by the fundus (5 patients) and anterior wall (4 patients). Of the 7 patients with a retroverted uterus, 4 had uterine perforation during BRT. In 67 patients with MRI delivered before BRT, only 3 (4%) had uterine perforation, and 2 of the 3 patients with uterine perforation had a retroverted uterus. However, of the 133 patients with no MRI evaluation before BRT, 14 (11%) had uterine perforation. No life-threatening complications or signs of intraperitoneal tumor cell seeding were observed.

CONCLUSIONS

Older age, larger tumors, a retroverted uterus, and a stenotic cervical os were all predisposing factors for uterine perforation during BRT. Preoperative MRI is a feasible and safe method to decrease the risks of uterine perforation and could be used preoperatively in centers where intraoperative ultrasonography is not used in routine practice.

Prognostic value of pretreatment 18F-fluorodeoxyglucose uptake in patients with cervical cancer treated with definitive chemoradiotherapy

OBJECTIVE

We analyzed the correlation of F-fluorodeoxyglucose (FDG) uptake into primary tumors using the maximum standardized uptake value (SUVmax) and clinicopathological factors of disease. The impact of the pretreatment SUVmax of the primary tumor on survival was investigated.

MATERIALS AND METHODS

The records of 149 patients with biopsy-proven cervical cancer treated with definitive chemoradiotherapy (ChRT) were reviewed. All patients underwent pretreatment FDG positron emission tomography with computed tomography, and posttherapy FDG positron emission tomography with computed tomography was performed within a median interval of 4.2 months (range, 3.0-11.2 months) after the completion of chemoradiotherapy.

RESULTS

The mean SUVmax in patients with lymph node metastasis was significantly higher than that in patients without metastasis (19.7 ± 8.2 vs 16.4 ± 8.2, respectively; P = 0.01). A significant difference existed between tumor size (<4 vs ≥4 cm) and the primary tumor SUVmax (14.7 ± 6.6 vs 18.7 ± 8.5, respectively; P = 0.02). The primary tumor pretreatment SUVmax for patients with complete remission was significantly lower than that of patients with partial response or progressive disease (15.6 ± 5.7 vs 28.0 ± 9.9, respectively; P < 0.001). The relationship between primary tumor FDG uptake and survival was evaluated by the cutoff value determined by receiver operating characteristic curve analysis. The area under the curve was 0.901 (P < 0.001; 95% confidence interval, 0.848-0.954), and 15.6 was determined as the SUVmax cutoff value. The 4-year actuarial overall survival (OS) and disease-free survival for SUVmax of less than 15.6 compared with SUVmax of 15.6 or greater were 85% vs 34% (P < 0.001) and 80% vs 29%, respectively (P < 0.001). In multivariate analysis, age, SUVmax of 15.6 or greater, and lymph node metastasis were independent prognostic factors of OS, and International Federation of Gynecology and Obstetrics stage IIB or higher, SUVmax of 15.6 or greater, and lymph node metastasis were significant factors for disease-free survival.

CONCLUSION

The primary tumor pretreatment SUVmax is correlated with increased tumor size and lymph node involvement at diagnosis, how well the primary tumor responds to treatment, the likelihood of disease recurrence, and OS.

Isolated mediastinal lymph node false positivity of [18F]-fluorodeoxyglucose-positron emission tomography/computed tomography in patients with cervical cancer

OBJECTIVE

This study aimed to evaluate the degree of mediastinal involvement in patients with cervical cancer with isolated mediastinal [F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) positivity as verified by histopathologic examination.

METHODS

Two hundred twenty-eight patients with newly diagnosed cervical cancer and who underwent FDG-PET imaging were analyzed. Twenty-nine patients (17%) had disseminated disease detected with PET/computed tomography (CT). Only 10 patients (4%) had increased FDG uptake in mediastinal lymph nodes alone. Of the 10 patients with mediastinal disease, 2 refused surgical mediastinal lymph node biopsy and did not receive any treatment. Patients with suspected paratracheal or subcarinal lymph node metastasis detected on PET/CT underwent mediastinoscopy, and those with hilar metastasis had video-assisted mediastinal lymphadenectomy. Treatment was delivered according to final staging based on histopathologic confirmation of mediastinal lymph node involvement.

RESULTS

The mean (SD) maximum standardized uptake values for primary cervical tumor and mediastinal lymph nodes were 19.7 (10.3) and 7.5 (1.6), respectively. Of 8 patients who underwent mediastinal lymph node confirmation, 6 (75%) were tumor free, demonstrating granulomatous changes, and were treated curatively. No patients had residual or recurrent disease at the primary site, and all but 1 were alive without disease. Two patients with confirmed mediastinal lymph node metastasis were treated palliatively and died between 9 and 11 months after diagnosis.

CONCLUSIONS

Positron emission tomography/CT is an important tool for lymphatic staging and evaluation of distant metastases in cervical cancer. However, PET/CT should be interpreted cautiously for isolated mediastinal involvement; surgical evaluation is required for accurate staging and appropriate treatment decisions to achieve better outcomes.

Non isocentric film-based intracavitary brachytherapy planning in cervical cancer: a retrospective dosimetric analysis with CT planning

Purpose

To compare intracavitary brachytherapy dose estimation for organs at risk (bladder and rectum) based on semi-orthogonal reconstruction of radiographs on non-isocentric X-ray unit and Computed Tomography (CT) – based volumetric planning in cervical cancer.

Material and methods

Bladder and rectal points as per International Commission on Radiation Units and Measurements (ICRU) report 38, were retrospectively evaluated on 15 high dose rate intracavitary brachytherapy applications for cervical cancer cases. With the same source configuration as obtained during planning on radiographs performed on a non-isocentric X-ray unit, the mean doses to 2cc of most irradiated part of bladder and rectum were computed by CT planning and these estimates were compared with the doses at ICRU bladder and rectal points.

Results

The mean ICRU point dose for bladder was 3.08 Gy (1.9-5.9 Gy) and mean dose to 2 cc (D2cc) bladder was 6.91 Gy (2.9-12.2 Gy). ICRU rectal dose was 3.8 Gy (2.4-4.45 Gy) and was comparable with D2cc rectum dose 4.2 Gy (2.8-5.9 Gy). Comparison of mean total dose (ICRU point vs. D2cc) for each patient was found to be significantly different for bladder (p = 0.000), but not for rectum (p = 0.08).

Conclusions

On comparison of ICRU point based planning with volumetric planning on CT, it was found that bladder doses were underestimated by the film based method. However, the rectal doses were found to be similar to the D2cc doses. The results with non isocentric film based treatment planning were similar to the existing literature on orthogonal film based simulator planning.

A retrospective analysis of rectal and bladder dose for gynecological brachytherapy treatments with GZP6 HDR afterloading system

AIM

The aim of this work is to evaluate rectal and bladder dose for the patients treated for gynecological cancers.

BACKGROUND

The GZP6 high dose rate brachytherapy system has been recently introduced to a number of radiation therapy departments in Iran, for treatment of various tumor sites such as cervix and vagina.

MATERIALS AND METHODS

Our analysis was based on dose measurements for 40 insertions in 28 patients, treated by a GZP6 unit between June 2009 and November 2010. Treatments consisted of combined teletherapy and intracavitary brachytherapy. In vivo dosimetry was performed with TLD-400 chips and TLD-100 microcubes in the rectum and bladder.

RESULTS

The average of maximum rectal and bladder dose values were found to be 7.62 Gy (range 1.72-18.55 Gy) and 5.17 Gy (range 0.72-15.85 Gy), respectively. It has been recommended by the ICRU that the maximum dose to the rectum and bladder in intracavitary treatment of vaginal or cervical cancer should be lower than 80% of the prescribed dose to point A in the Manchester system. In this study, of the total number of 40 insertions, maximum rectal dose in 29 insertions (72.5% of treatment sessions) and maximum bladder dose in 18 insertions (45% of treatments sessions) were higher than 80% of the prescribed dose to the point of dose prescription.

CONCLUSION

In vivo dosimetry for patients undergoing treatment by GZP6 brachytherapy system can be used for evaluation of the quality of brachytherapy treatments by this system. This information could be used as a base for developing the strategy for treatment of patients treated with GZP6 system.

Adaptive brachytherapy of cervical cancer, comparison of conventional point A and CT based individual treatment planning

BACKGROUND

Locally advanced cervical cancer is commonly treated with external radiation therapy combined with local brachytherapy. The brachytherapy is traditionally given based on standard dose planning with prescription of dose to point A. Dosimetric aspects when changing from former standard treatment to individualized treatment plans based on computed tomography (CT) images are here investigated.

MATERIAL AND METHODS

Brachytherapy data from 19 patients with a total of 72 individual treatment fractions were retrospectively reviewed. Standard library plans were analyzed with respect to doses to organs at risk (OARs), and the result was compared to corresponding delivered individualized plans. The theoretical potential of further optimization based on prescription to target volumes was investigated. The treatments were performed with a Fletcher applicator.

RESULTS

For standard treatment planning, the tolerance dose limits were exceeded in the bladder, rectum and sigmoid in 26%, 4% and 15% of the plans, respectively. This was observed most often for the smallest target volumes. The individualized planning of the delivered treatment gave the possibility of controlling the dose to critical organs to below certain limits. The dose was still prescribed to point A. An increase in target dose coverage was achieved when additional individual optimization was performed, while still keeping the dose to the OARs below predefined limits. Relatively low average target coverage, especially for the largest volumes was however seen.

CONCLUSION

The individualized delivered treatment plans ensured that doses to OARs were within acceptable limits. This was not the case in 42% of the corresponding standard plans. Further optimized treatment plans were found to give an overall better dose coverage. In lack of MR capacity, it may be favorable to use CT for planning due to possible protection of OARs. The CT based target volumes were, however, not equivalent to the volumes described in magnetic resonance imaging (MRI) based recommendations. Prescription and assessment of dose, when introducing such target volumes, should be evaluated and preferably compared to well known treatment regimens.