An atlas to aid delineation of para-aortic lymph node region in cervical cancer: Design and validation of contouring guidelines

Study protocol of Elective Para-aortic and pelvic versus Pelvic only Irradiation in pelvic node positive Cervical cancer: a multicentric open labelled phase III randomised controlled trial (EPIC Study)

INTRODUCTION

The revision of International Federation of Gynaecology and Obstetrics staging in 2018 with recommendations to include cross-sectional imaging and a separate stage for node positive disease have opened a lot of uncertainties in implementing the correct treatment approach in these patients. While studies have suggested higher chances of occult para-aortic lymph node (PALN) even with advanced imaging, especially in pelvic node positive disease which tend to recur after pelvic radiation therapy. This study intends to study these patients and isolate the subset who will benefit most from elective PALN irradiation.

METHODS AND ANALYSIS

This is an ongoing multicentric phase III randomised controlled trial with a sample size of 274 subjects in two arms (137 in each arm) to determine the superiority of limited elective para-aortic irradiation compared with no irradiation. Arm one includes radiation to the lower PALN and pelvis; Arm two includes radiation to the pelvis. Concurrent chemotherapy followed by brachytherapy is standard in both arms. Patients with cervical cancer and radiologically positive pelvic LNs aged>18 years and<70 years are screened for the study. The primary endpoint of this study is 3-year disease-free survival. The secondary endpoints include 3-year para-aortic recurrence-free survival, 3-year distant metastasis-free survival, 3-year overall survival, acute and late toxicity, quality of life. Translational study to evaluate systemic immune response by FAPI-PETCT (fibroblast activator protein inhibitor positron emission tomography) and assessment of p16, L1 cell adhesion molecule (L1CAM) and protein death ligand-1 (PDL-1) expression by immunohistochemistry.

ETHICS AND DISSEMINATION

The study has been approved by the institutional ethics committee and will be routinely monitored according to standard guidelines. The results of the study will be published in peer-reviewed scientific journals, presented at conferences and submitted to regulatory authorities.

TRIAL REGISTRATION NUMBER

The study was registered on 17 January 2022 under CTRI/2022/01/039495 (http://ctri.nic.in).

Optimal Correction Strategy of Image Guided Radiation Therapy Including the Paraortic Lymph Node Region in Patients With Cervical Cancers

Purpose

The clinically accepted planning target volume margin for radiation therapy to the paraortic nodal region in cervical cancer patients is 5 mm. However, the comprehensive alignment and variability from the pelvic bone to all lumbar vertebrae are undetermined. This study aims to quantify the residual setup errors between the pelvic bone and lumbar vertebrae and determine the optimal correction strategy for patients with cervical cancer.

Materials and Methods

Fifteen patients underwent pretreatment mega-voltage computed tomography scans (375 total fractions). Residual setup errors and required margins for each lumbar vertebra were calculated based on registrations accounting for pelvic rotation and translation.

Results

The systematic residual errors (1 SD) at L1, L2, L3, L4, and L5 using pelvic bone registration were 6.5, 4.9, 3.1, 1.5, and 0.6 mm in the anterior-posterior (AP) direction, 3.1, 2.3, 1.4, 0.6, and 0.3 mm in the right-left direction, and 2.7, 2.2, 1.7, 1.0, and 0.5 mm in the superior-inferior direction, respectively. The residual setup errors were the largest in the AP direction. Registration based on the pelvic bone required margins in the AP direction of 16.0, 12.1, 7.7, 3.6, and 1.3 mm for L1, L2, L3, L4, and L5, respectively, whereas registration based on L3 required margins of 8.8, 4.8, 4.4, 7.1, and 7.7 mm for L1, L2, L4, L5, and pelvic bone, respectively.

Conclusions

Considerable local setup variability was found in patients with cervical cancer. After reviewing the corrective strategies, we determined that L3-based registration effectively minimized the required margins.

Quality Assurance in Radiotherapy (RT)-Specific Trials: Indian Scenario

AIMS

There is evidence that proper radiotherapy trial quality assurance (RTTQA) translates into improved outcomes for patients. However, the practice of RTTQA is heterogeneous and implemented in a diverse manner across trials. In this paper, we review the RTTQA report for randomised trials (RCT) conducted in India and present our experience with RTTQA for various clinical trials and highlight the key achievements and challenges.

MATERIALS AND METHODS

Search was performed using the keywords and the variations thereof for "radiotherapy" and author affiliations from India, its states and major metropolitan cities. Pubmed search filters were used to restrict results to RCT published in the past 5 years (2019-2024). Reporting of RTTQA procedures from publications and protocols was documented along with the protocol-specified dosimetric goals. We also evaluated a few clinical trials performed in the Department of Radiation Oncology at Tata Medical Center. The different RTTQA procedures and results for four representative clinical trials have been described.

RESULTS

A formal RTTQA process was reported by only one out of 24 randomised controlled trials and formal dosimetric goals were pre-specified by 9 of 13 trials where IMRT was used as treatment. RTTQA requirements were tailored for each clinical trial at Tata Medical Center. For the HYPORT trial, the RTTQA process focused on ensuring the matchline doses were homogenous. HYPORT B trial commissioned the use of a simultaneous integrated boost technique which emphasised conformal avoidance of dose spillage to contralateral breast and lung. HYPORT Adjuvant and PROPARA trials are multicentre clinical trials. While HYPORT Adjuvant focussed on ensuring that the dose delivery met the predefined constraints, segmentation of the target volume was important for the PROPARA trial.

CONCLUSION

We demonstrate different RTTQA procedures required for representative clinical trials and highlight key challenges encountered.

Comparative analysis of simultaneous integrated boost and sequential boost radiotherapy in node-positive cervical cancer: dosimetric and radiobiological considerations

For locally advanced cervical cancer, the standard therapeutic approach involves concomitant chemoradiation therapy, supplemented by a brachytherapy boost. Moreover, an external beam radiotherapy (RT) boost should be considered for treating gross lymph node (LN) volumes. Two boost approaches exist with Volumetric Intensity Modulated Arc Therapy (VMAT): Sequential (SEQ) and Simultaneous Integrated Boost (SIB). This study undertakes a comprehensive dosimetric and radiobiological comparison between these two boost strategies. The study encompassed ten patients who underwent RT for cervical cancer with node-positive disease. Two sets of treatment plans were generated for each patient: SIB-VMAT and SEQ-VMAT. Dosimetric as well as radiobiological parameters including tumour control probability (TCP) and normal tissue complication probability (NTCP) were compared. Both techniques were analyzed for two different levels of LN involvement - only pelvic LNs and pelvic with para-aortic LNs. Statistical analysis was performed using SPSS software version 25.0. SIB-VMAT exhibited superior target coverage, yielding improved doses to the planning target volume (PTV) and gross tumour volume (GTV). Notably, SIB-VMAT plans displayed markedly superior dose conformity. While SEQ-VMAT displayed favorable organ sparing for femoral heads, SIB-VMAT appeared as the more efficient approach for mitigating bladder and bowel doses. TCP was significantly higher with SIB-VMAT, suggesting a higher likelihood of successful tumour control. Conversely, no statistically significant difference in NTCP was observed between the two techniques. This study's findings underscore the advantages of SIB-VMAT over SEQ-VMAT in terms of improved target coverage, dose conformity, and tumour control probability. In particular, SIB-VMAT demonstrated potential benefits for cases involving para-aortic nodes. It is concluded that SIB-VMAT should be the preferred approach in all cases of locally advanced cervical cancer.

Assessment of lymph node area coverage with total marrow irradiation and implementation of total marrow and lymphoid irradiation using automated deep learning-based segmentation

BACKGROUND

Total marrow irradiation (TMI) and total marrow and lymphoid irradiation (TMLI) have the advantages. However, delineating target lesions according to TMI and TMLI plans is labor-intensive and time-consuming. In addition, although the delineation of target lesions between TMI and TMLI differs, the clinical distinction is not clear, and the lymph node (LN) area coverage during TMI remains uncertain. Accordingly, this study calculates the LN area coverage according to the TMI plan. Further, a deep learning-based model for delineating LN areas is trained and evaluated.

METHODS

Whole-body regional LN areas were manually contoured in patients treated according to a TMI plan. The dose coverage of the delineated LN areas in the TMI plan was estimated. To train the deep learning model for automatic segmentation, additional whole-body computed tomography data were obtained from other patients. The patients and data were divided into training/validation and test groups and models were developed using the "nnU-NET" framework. The trained models were evaluated using Dice similarity coefficient (DSC), precision, recall, and Hausdorff distance 95 (HD95). The time required to contour and trim predicted results manually using the deep learning model was measured and compared.

RESULTS

The dose coverage for LN areas by TMI plan had V100% (the percentage of volume receiving 100% of the prescribed dose), V95%, and V90% median values of 46.0%, 62.1%, and 73.5%, respectively. The lowest V100% values were identified in the inguinal (14.7%), external iliac (21.8%), and para-aortic (42.8%) LNs. The median values of DSC, precision, recall, and HD95 of the trained model were 0.79, 0.83, 0.76, and 2.63, respectively. The time for manual contouring and simply modified predicted contouring were statistically significantly different.

CONCLUSIONS

The dose coverage in the inguinal, external iliac, and para-aortic LN areas was suboptimal when treatment is administered according to the TMI plan. This research demonstrates that the automatic delineation of LN areas using deep learning can facilitate the implementation of TMLI.

Clinical Outcomes and Prognostic Factors in Stage III C Cervical Cancer Patients Treated with Radical Radiotherapy or Radiochemotherapy

Objective: Since the update of the 2018 International Federation of Gynecology and Obstetrics (FIGO) staging criteria, there have been few reports on the prognosis of stage III C cervical cancer. Moreover, some studies have drawn controversial conclusions, necessitating further verification. This study aims to evaluate the clinical outcomes and determine the prognostic factors for stage III C cervical cancer patients treated with radical radiotherapy or radiochemotherapy. Methods: The data of 117 stage III C cervical cancer patients (98 III C1 and 19 III C2) who underwent radical radiotherapy or radiochemotherapy were retrospectively analyzed. We evaluated 3-year overall survival (OS) and disease-free survival (DFS) using the Kaplan-Meier method. Prognostic factors were analyzed using the Log-rank test and Cox proportional hazard regression model. The risk of para-aortic lymph node metastasis (LNM) in all patients was assessed through Chi-squared test and logistic regression analysis. Results: For stage III C1 and III C2 patients, the 3-year OS rates were 77.6% and 63.2% (P = .042), and the 3-year DFS rates were 70.4% and 47.4% (P = .003), respectively. The pretreatment location of pelvic LNM, histological type, and FIGO stage was associated with OS (P = .033, .003, .042, respectively); the number of pelvic LNM and FIGO stage were associated with DFS (P = .015, .003, respectively). The histological type was an independent prognostic indicator for OS, and the numbers of pelvic LNM and FIGO stage were independent prognostic indicators for DFS. Furthermore, a pelvic LNM largest short-axis diameter ≥ 1.5 cm and the presence of common iliac LNM were identified as high-risk factors influencing para-aortic LNM in stage III C patients (P = .046, .006, respectively). Conclusions: The results of this study validated the 2018 FIGO staging criteria for stage III C cervical cancer patients undergoing concurrent chemoradiotherapy. These findings may enhance our understanding of the updated staging criteria and contribute to better management of patients in stage III C.

Controversies in the Staging of Patients with Locally Advanced Cervical Cancer

Approximately 10-25% of patients with locally advanced cervical cancer harbor metastases to the para-aortic lymph nodes. Staging of patients with locally advanced cervical cancer can be performed with imaging techniques, such as PET-CT; however, false negative rates can be as high as 20%, especially for patients with pelvic lymph node metastases. Surgical staging can identify patients with microscopic lymph nodes metastases and aid in accurate treatment planning with the administration of extended-field radiation therapy. Data from retrospective studies investigating the impact of para-aortic lymphadenectomy on the oncological outcomes of patients with locally advanced cervical cancer are mixed, while data from randomized controlled trials do not demonstrate a progression-free survival benefit. In the present review, we explore controversies in the staging of patients with locally advanced cervical cancer and summarize the available literature.

Comprehensive clinical evaluation of deep learning-based auto-segmentation for radiotherapy in patients with cervical cancer

Background and purpose

Deep learning-based models have been actively investigated for various aspects of radiotherapy. However, for cervical cancer, only a few studies dealing with the auto-segmentation of organs-at-risk (OARs) and clinical target volumes (CTVs) exist. This study aimed to train a deep learning-based auto-segmentation model for OAR/CTVs for patients with cervical cancer undergoing radiotherapy and to evaluate the model's feasibility and efficacy with not only geometric indices but also comprehensive clinical evaluation.

Materials and methods

A total of 180 abdominopelvic computed tomography images were included (training set, 165; validation set, 15). Geometric indices such as the Dice similarity coefficient (DSC) and the 95% Hausdorff distance (HD) were analyzed. A Turing test was performed and physicians from other institutions were asked to delineate contours with and without using auto-segmented contours to assess inter-physician heterogeneity and contouring time.

Results

The correlation between the manual and auto-segmented contours was acceptable for the anorectum, bladder, spinal cord, cauda equina, right and left femoral heads, bowel bag, uterocervix, liver, and left and right kidneys (DSC greater than 0.80). The stomach and duodenum showed DSCs of 0.67 and 0.73, respectively. CTVs showed DSCs between 0.75 and 0.80. Turing test results were favorable for most OARs and CTVs. No auto-segmented contours had large, obvious errors. The median overall satisfaction score of the participating physicians was 7 out of 10. Auto-segmentation reduced heterogeneity and shortened contouring time by 30 min among radiation oncologists from different institutions. Most participants favored the auto-contouring system.

Conclusion

The proposed deep learning-based auto-segmentation model may be an efficient tool for patients with cervical cancer undergoing radiotherapy. Although the current model may not completely replace humans, it can serve as a useful and efficient tool in real-world clinics.

Recommendations of the clinical target volume for the para-aortic region based on the patterns of lymph node metastasis in patients with biliary tract cancer

BACKGROUND

Even though the clinical target volume (CTV) in biliary tract cancer (BTC) patients has been proposed by several previous studies, the para aortic CTV for BTC is still not well-defined. The objective of this study was to determine the precise delineation of the para aortic CTV for BTC according to the distribution pattern and failure pattern of lymph nodes.

METHODS

Computed tomography (CT)-, magnetic resonance imaging (MRI)- or positron emission tomography-computed tomography (PET-CT)-generated images of patients with BTC from 2015 to 2020 were analyzed retrospectively. The distribution patterns of lymph nodes in different regions were summarized. The diagnosed para aortic lymph nodes (PALNs) were manually mapped to standard axial CT images. The asymmetric CTV expansions from the para aortic were defined according to the distance from the volumetric centre of lymph node to the most proximal border of aorta.

RESULTS

A total of 251 positive lymph nodes were found in the study cohort (n = 61 patients, 92 PALN). All PALNs were projected onto axial CT image of the standard patient. PALNs were concentrated in the 16a2 and 16b1 regions, and the involvement rates were 17% and 13% respectively. Therefore, the upper boundary of 16a2 and the lower boundary of 16b1 were defined as the cranial and caudal border of para aortic CTV, respectively. For the study cohort, the mean distance from the volume center of all lymph nodes in 16a2 and 16b1 to the proximal border of the aorta was 9 mm (range 4-24) in the front, 7 mm (range 3-14) on the left, and 12 mm (range 5-29) on the right. For the validation cohort (n=19 patients, 56 PALN), the mean distance from the center of the lymph node to the border of the aorta were both 10 mm on the left (range 5-20) and right (range 6-23). The mean distance in front of the aorta was 9 mm (range 5-23). Finally, a CTV expansion from the aorta of 18 mm in the front, 12 mm on the left, and 24 mm on the right resulted in 96% (73/76) coverage of PALNs in the study cohort. At the time of the validation, the described CTV could include 96% (47/49) of recurrent PALNs in the validation cohort.

CONCLUSIONS

The involvement rates of PALNs in 16a2 and 16b1 were the highest. Based on the distribution of PALNs, a new para-aortic CTV was defined to construct a more accurate target volume for adjuvant radiotherapy in BTC.

Prophylactic extended-field irradiation for locally advanced cervical cancer

Concomitant chemoradiotherapy is the standard treatment for locally advanced cervical cancer. Pelvic irradiation is commonly recommended for patients with negative para-aortic lymph nodes(PALNs). However, owing to the development of imaging-guided brachytherapy, distant failure has become the main failure pattern. The PALNs are a vital site of distant metastasis, and the para-aortic region may contain occult microscopic metastases that are barely detected owing to imaging technology restriction. The prognostic of patients who experienced PALN failure is dismal. Typically, there are four ways to decrease PALN failure. First, surgical staging can be performed to assess the occurrence of metastasis in the para-aortic region; however, the application of surgical staging is decreasing owing to controversial survival benefits and accompanying complications of surgery. Second, regular imaging surveillance and timely salvage of early recurrences could reduce PALN failure. Third, better systemic adjuvant therapy could be recommended since it has enormous potential to reduce distant metastases and improve overall survival. Fourth, performing prophylactic extended-field irradiation (EFI), including pelvic and para-aortic region irradiation, can sterilize occult microscopic metastases in the para-aortic region and improve survival. Prior investigations have revealed that prophylactic EFI could reduce PALN failure as well as distant metastasis and present the benefit of survival. Yet, owing to the serious morbidity induced by enlarged irradiation field in the era of conventional irradiation techniques, further research on EFI is stagnated. Nowadays, with the development of new technologies, intensity modulated radiation therapy can deliver a higher dose to tumors with acceptable toxicity. Prophylactic EFI regained attention. However, the inclusion criteria of prophylactic EFI in existing studies reveal great discrepancies. Thus, it is urgent to precisely identify indications for better survival and lower complications in patients with cervical cancer. In this review, we identify indications and summary guidelines for prophylactic EFI, which may provide a foundation for further trials and clinical applications.

Optimal prophylactic para-aortic radiotherapy in locally advanced cervical cancer: anatomy-based versus margin-based delineation

OBJECTIVE

Precise delineation of the para-aortic nodal region is critical for the optimal therapeutic ratio of prophylactic para-aortic radiotherapy. We aimed to evaluate the para-aortic control and patient-reported gastrointestinal toxicity in patients with locally advanced cervical cancer who received anatomy-based or margin-based prophylactic para-aortic radiotherapy.

METHODS

We analyzed 160 patients with locally advanced cervical cancer who received prophylactic extended-field radiotherapy between January 2014 and November 2019 at two tertiary centers. Para-aortic nodal regions were delineated based on the anatomic principle-based atlas or marginal expansion from the aorta and inferior vena cava. The Patient-Reported Outcome version of the Common Terminology Criteria for Adverse Events was used to assess acute gastrointestinal toxicity, and a score of ≥3 was defined as severe gastrointestinal toxicity.

RESULTS

Seventy-six (47.5%) and 84 (52.5%) patients received anatomy-based and margin-based prophylactic para-aortic radiotherapy, respectively. The median follow-up was 40.1 months (IQR 25.5-58.9). Para-aortic nodal failures occurred in one (1.3%) patient in the anatomy-based para-aortic radiotherapy group and in one (1.2%) patient in the margin-based para-aortic radiotherapy group (p=1.00). There was no in-field or marginal para-aortic nodal failure. The 3-year para-aortic recurrence-free survival for anatomy-based and margin-based para-aortic radiotherapy was 98.6% and 98.8%, respectively (p=0.94). Patients who received anatomy-based para-aortic radiotherapy reported less severe acute gastrointestinal toxicity than those who received margin-based para-aortic radiotherapy (13.2% vs 29.8%, p=0.01). A comparison of gastrointestinal toxicities showed that patients who received anatomy-based para-aortic radiotherapy reported significantly less severe gastrointestinal toxicity than those who received margin-based para-aortic radiotherapy in terms of frequency of diarrhea (7.9% vs 20.2%, p=0.03), severity of abdominal pain (3.9% vs 14.3%, p=0.03), and interference of abdominal pain (2.6% vs 11.9%, p=0.03).

CONCLUSION

Anatomy-based prophylactic para-aortic radiotherapy achieved excellent para-aortic control and a lower incidence of severe patient-reported gastrointestinal toxicity. These findings suggest that anatomy-based delineation optimizes clinical outcomes of prophylactic para-aortic radiotherapy in locally advanced cervical cancer.

A modified delineation method of para-aortic nodal clinical target volume in patients with locally advanced cervical cancer

PURPOSE

To validate the nodal center coverage (NCC) of the three mainstream delineation methods of para-aortic nodal clinical target volume (CTV) and propose a modified delineation method of para-aortic nodal CTV in prophylactic extended-field irradiation (EFI) of cervical cancer.

METHODS

A total of 106 patients with para-aortic lymph nodes (PALNs) identified on PET/CT were included at Peking Union Medical College Hospital between 2011 and 2020. PALNs were classified as left lateral para-aortic (LLPA), aorto-caval (AC), and right para-caval (RPC). Distances from the nodal center to the aorta and inferior vena cava (IVC) were measured. The NCC of the three mainstream delineation methods of para-aortic nodal CTV (CTV-K, CTV-S, and CTV-D) and a modified CTV (CTV-M) was calculated. Radiotherapy plans were created based on 4 CTVs for 10 selected patients who received prophylactic EFI. The chi-squared test and the Student's t-test were performed.

RESULTS

We identified 344 PALNs (216 LLPA, 101 AC, and 27 RPC) in 106 patients. Mean distance from the nodal center to the aorta was 9.6 mm in the LLPA and 7 mm in the AC and from the nodal center to the IVC was 5.6 mm in the AC and 5.6 mm in the RPC. CTV-D improved the NCC of 98% compared with 92% for CTV-K (p = 0.002) and 95% for CTV-S (p = 0.046). CTV-M provided the same satisfactory NCC as CTV-D (97% vs. 98%, p = 0.485). The V_50Gy to the duodenum, the D_mean to the bilateral kidneys, and the V_45Gy to the small bowel were significantly lower on the CTV-M-based plan than on the CTV-D-based plan (p = 0.001, 0.011, and 0.001, respectively).

CONCLUSION

CTV-D provided more satisfactory NCC than CTV-K and CTV-S. CTV-M provided the same satisfactory NCC as CTV-D and reduced the dose to the critical structures.

Validation and applicability of para-aortic lymph nodal contouring atlas in cervical cancer

BACKGROUND AND PURPOSE

CTV delineation guidelines for the para-aortic nodal region for patients with cervical cancer have been proposed (Keenan et al., 2018). The purpose of this study was to validate these guidelines with the use of CT datasets of cervical cancer patients with macroscopic PALN treated with definitive (chemo)radiation (CTRT) at our center.

MATERIALS AND METHODS

Planning CT datasets of 71 cervical cancer patients with gross PA nodal disease treated with EFRT were used. Two hundred and two PALN were identified based on size and morphology on diagnostic CECT, PET CT, or histologically proven PALN. LN regions were divided into upper, middle, and lower and based on their relation to the aorta and IVC. Macroscopic PALN were contoured, and the CTV for PALN irradiation was generated based on the proposed guidelines on ECLIPSE (Version 13.5). The centre of mass (COM_N) was calculated for each gross PALN. The evaluation was done to review the presence of COM_N in relation to the CTV PALN.

RESULTS

The most common location of PALN was Left para-aortic (105 LN-52%), Aortocaval (55 LN-27.2%), and Precaval (14 LN-6.9%). Lower PALN were the commonest (104 LN-51.5%). Ninety-three were middle PALN (46%), and 5 were upper PALN (2.5%). After excluding upper PALN, COM_N for 11 PALN (5.5%) were outside the CTV while 20 were junctional.

CONCLUSION

Our study shows that more than 95% of PALN in this patient cohort were covered using these guidelines with the addition of an extra 5 mm margin laterally on the left.

An Adversarial Deep-Learning-Based Model for Cervical Cancer CTV Segmentation With Multicenter Blinded Randomized Controlled Validation

Purpose

To propose a novel deep-learning-based auto-segmentation model for CTV delineation in cervical cancer and to evaluate whether it can perform comparably well to manual delineation by a three-stage multicenter evaluation framework.

Methods

An adversarial deep-learning-based auto-segmentation model was trained and configured for cervical cancer CTV contouring using CT data from 237 patients. Then CT scans of additional 20 consecutive patients with locally advanced cervical cancer were collected to perform a three-stage multicenter randomized controlled evaluation involving nine oncologists from six medical centers. This evaluation system is a combination of objective performance metrics, radiation oncologist assessment, and finally the head-to-head Turing imitation test. Accuracy and effectiveness were evaluated step by step. The intra-observer consistency of each oncologist was also tested.

Results

In stage-1 evaluation, the mean DSC and the 95HD value of the proposed model were 0.88 and 3.46 mm, respectively. In stage-2, the oncologist grading evaluation showed the majority of AI contours were comparable to the GT contours. The average CTV scores for AI and GT were 2.68 vs. 2.71 in week 0 (P = .206), and 2.62 vs. 2.63 in week 2 (P = .552), with no significant statistical differences. In stage-3, the Turing imitation test showed that the percentage of AI contours, which were judged to be better than GT contours by ≥5 oncologists, was 60.0% in week 0 and 42.5% in week 2. Most oncologists demonstrated good consistency between the 2 weeks (P > 0.05).

Conclusions

The tested AI model was demonstrated to be accurate and comparable to the manual CTV segmentation in cervical cancer patients when assessed by our three-stage evaluation framework.

Higher Dose to Organs at Risk: The Unintended Consequences of Intravenous Contrast Use in Computed Tomography Simulation for Cervical Cancer

PURPOSE

To compare the volumes of interest and doses to the organs at risk on contrast and noncontrast scans in patients with cervical cancer who underwent prophylactic extended-field radiation therapy (EFRT).

METHODS AND MATERIALS

We reviewed twenty cervical cancer patients treated with prophylactic EFRT at Peking Union Medical College Hospital between March 2021 and April 2021. Each patient underwent noncontrast and contrast scans during simulation. All structures were contoured, and radiation therapy plans were created based on both scans. Student t test and Pearson correlation coefficient test were performed.

RESULTS

Compared with the noncontrast scan, on the contrast scan, the mean volume of the inferior vena cava expanded by 44% (P ≤ .001), and the mean volume of the para-aortic nodal clinical target volume increased by 17% (P ≤ .001). For the second portion of the duodenum, the V30 (38.2% vs 43.8%, P = .038), V35 (27.6% vs 35.1%, P = .002), V40 (18.3% vs 26.3%, P = .014), V45 (11.2% vs 18.5%, P = .008), and V50 (4.2% vs 9.1%, P = .005) were significantly lower on the noncontrast scan than on the contrast scan. For the third portion of the duodenum, the V45 (78.4% vs 81.6%, P = .03) and V50 (59.7% vs 67%, P ≤ .001) were significantly lower on the noncontrast scan than on the contrast scan. For the right kidney, the V5, V10, V15, V20, and V25 on the contrast and noncontrast scans were 85.4% versus 79.8% (P = .013), 52.5% versus 45.6% (P = .021), 25.6% versus 20.1% (P = .003), 11.1% versus 7.5% (P = .001), and 3.8% versus 2.3% (P = .027), respectively.

CONCLUSIONS

Compared with the noncontrast scan, expansion of the inferior vena cava on the contrast scan can lead to excessive contouring and an overdose to the duodenum and right kidney in cervical cancer patients treated with prophylactic EFRT.

Mapping patterns of para-aortic lymph node recurrence in cervical cancer: a retrospective cohort analysis

BACKGROUND

To map anatomic patterns of para-aortic lymph node (PALN) recurrence in cervical cancer patients and validate currently available guidelines on PA clinical target volumes (CTV).

METHODS

Cervical cancer patients who developed PALN recurrence were included. The PALNs were classified as left-lateral para-aortic (LPA), aorto-caval (AC), and right para-caval (RPC). Four PA CTVs were contoured for each patient to validate PALN coverage. CTV_RTOG was contoured based on the Radiation Therapy Oncology Group guideline. CTV_K was contoured as proposed by Keenan et al. CTV_M was contoured by expanding symmetrical margins around the aorta and inferior vena cava of 7 mm up to the T12-L1 interspace. CTV_new was created by modifying CTV_RTOG to obtain better coverage.

RESULTS

We identified 92 PALNs in 35 cervical cancer patients. 46.8% of the PALNs were at LPA, 38.0% were at AC, and 15.2% were at RPC areas. CTV_RTOG, CTV_K, and CTV_M covered 87.0%, 88.0%, and 62.0% of all PALNs, respectively. PALN recurrence above the left renal vein was associated with PALN involvement at diagnosis (p = 0.043). Extending upper border to the superior mesenteric artery allowed the CTV_new to cover 96.7% of all PALNs and all nodes in 91.4% of patients.

CONCLUSION

CTV_RTOG and CTV_K encompassed most PALN recurrences. For high-risk patients, such as those having PALN involvement at diagnosis, extending the superior border of CTV from the left renal vein to superior mesenteric artery could be considered.

Para-aortic lymph node metastasis in lower Thoracic Esophageal Squamous Cell Carcinoma after Radical Esophagectomy: a CT-based atlas and its clinical implications for Adjuvant Radiotherapy

Background: Our previous work showed that para-aortic lymph node (PALN) metastasis was the major failure pattern in lower thoracic esophageal squamous cell carcinoma (LTESCC) patients who presented abdominal LN failure after curative surgery. We thereby aim to generate a computerized tomography (CT)-based documentation of PALNs and to propose a clinical target volume (CTV) for this region. Methods: Sixty-five patients were enrolled. The epicentre of each PALN was drawn onto an axial CT image of a standard patient with reference to the surrounding anatomical landmarks. A CTV for PALN was generated based on the final result of node distribution, and was evaluated for dosimetric performance in three simulated patients. Results: All the studied 248 LNs were below the level of 1.0 cm above the celiac artery (CA), and 94.76% were above the bottom of vertebra L3. Horizontally, 93.33% of the LNs in the celiac level were located within an expansion of 1.5 cm on the CA, and 94.12% of the LNs in the superior mesenteric artery (SMA) level were within 1.5 cm on the left side of the SMA. Below the SMA, all the LNs were behind the left renal vein, left to the right border of the inferior vena cava, and 98.51% of the LNs were medial to the lateral surface of the left psoas major. The proposed CTV could cover 92.74% of the LNs and was dosimetrically feasible. Conclusions: The proposed CTV is the first one to focus on the high-risk area of abdominal failure in LTESCC patients after surgery and can serve as a reference in the adjuvant radiotherapy for LTESCC patients.

Patterns of Treatment Failure after Concurrent Chemoradiotherapy or Adjuvant Radiotherapy in Patients with Locally Advanced Cervical Cancer

OBJECTIVE

To identify patterns of therapy failure after radiotherapy in Chinese patients with locally advanced cervical cancer (LACC).

METHODS

A retrospective study was conducted at a Chinese hospital from June 2012 to July 2018. All analyses were done using SPSS 26.

RESULTS

105 patients with treatment failure were included. After a median follow-up of 27 months (range 10-82), the 3-year survival rate after therapy failure was 19.4%. In multivariate analysis, squamous cell carcinoma antigen (SCC-Ag) <4 ng/mL (p < 0.001) and disease-free interval >12 months (p = 0.013) showed significant survival benefits. We identified 3 types of failure: distant lymph node metastasis (n = 50), hematogenous metastasis (n = 53) and pelvic failure (n = 48). Most metastatic para-aortic lymph nodes (PALN) were inferior to the level of left renal hilum (84.8%, n = 28). A total of 80% of patients with supraclavicular lymph nodes (SCLN) metastasis ignored imaging on supraclavicular region. For solitary SCLN or lung metastasis, the prognosis was better than that combined with other sites failure, respectively (p = 0.005; p = 0.001). Many patients with central sites recurrence received insufficient doses of intracavitary brachytherapy (IBT) for low tolerance to pain.

CONCLUSION

The distribution of metastatic PALN is asymmetrical and optimizing clinical target volume to minimize toxicity of para-aortic radiation is necessary. The effect of ultrasonography as preliminary screening and follow-up means on SCLN metastasis can be expected. Pain management and psychological interventions are essential for patients receiving IBT.

Updating and Optimizing Anatomic Atlases for Elective Radiation of Para-Aortic Lymph Nodes in Cervical Cancer

PURPOSE

Previous studies have proposed 2 different contouring guidelines for the prophylactic radiation of para-aortic lymph nodes (PANs) for locally advanced cervical cancer. Because PAN-mapping atlases in current literature are limited to small patient samples and nodal populations, we updated the PAN atlas with a large data set of positron emission tomography (PET)-positive PANs on PET/computed tomography (CT) from patients with cervical cancer.

METHODS AND MATERIALS

We identified 176 PET-positive PANs on pretreatment PET/CT of 47 patients with diagnosed International Federation of Gynecology and Obstetrics stage IB to IVA cervical cancer. PANs were classified as left-lateral para-aortic (LPA), aortocaval (AC), or right paracaval (RPC). PAN clinical target volume (CTV) contours were drawn for all patients based on previously published guidelines by Takiar (CTV-T) and Keenan (CTV-K) and nodal volumetric coverage was assessed.

RESULTS

We identified 94 LPA nodes (54%), 71 AC nodes (40%), and 11 (6%) RPC nodes. CTV-T had improved nodal center coverage of 97.6% compared with 85.0% for CTV-K (P < .001). Nodal center coverage for CTV-K and CTV-T (with corresponding PAN) were 79 (84.0%) and 93 (99.0%) LPA nodes (P = .001), 64 (90.1%) and 68 (95.8%) AC nodes (P = .221), and 5 (45.5%) and 9 (81.8%) RPC nodes (P = .134), respectively. Additionally, our updated PAN atlas identified nodal centers anterior to the aorta and inferior vena cava that are not covered by CTV-T but covered by CTV-K due to the 10 mm anterior aortic expansion of CTV-K.

CONCLUSIONS

We have updated the PAN anatomic map of 176 PET-positive nodes from 47 patients and demonstrated that CTV-T has significantly better PAN coverage over CTV-K for posterior LPA and retrocaval regions for our data set. Additionally, we suggest a modification that includes a blend of CTV-T and CTV-K to provide optimal coverage for the mapped nodes anterior to the great vessels in our data set.

Prophylactic Extended-Field Irradiation in Patients With Cervical Cancer: A Literature Review

Currently, the standard radiation field for locally advanced cervical cancer patients without evidence of para-aortic lymph node (PALN) metastasis is the pelvis. Due to the low accuracy of imaging in the diagnosis of PALN metastasis and the high incidence of PALN failure after pelvic radiotherapy, prophylactic pelvic and para-aortic irradiation, also called extended-field irradiation (EFI), is performed for patients with cervical cancer. In the era of concurrent chemoradiotherapy, randomized controlled trials are limited, and whether patients with cervical cancer can benefit from prophylactic EFI is still controversial. With conformal or intensity-modulated radiation therapy, patients tolerate prophylactic EFI very well. The severe toxicities of prophylactic EFI are not significantly higher than those of pelvic radiotherapy. We recommend delivering prophylactic EFI to cervical cancer patients with common iliac lymph nodes metastasis. Clinical trials are needed to investigate whether patients with ≥3 positive pelvic lymph nodes and FIGO stage IIIB disease can benefit from prophylactic EFI. According to the distribution of PALNs, it is reasonable to use the renal vein as the upper border of the radiation therapy field for patients treated with prophylactic EFI. The clinical target volume expansion of the node from the vessel should be smaller in the right para-caval region than in the left lateral para-aortic region. The right para-caval region above L2 or L3 may be omitted from the PALN target volume to reduce the dose to the duodenum. More clinical trials on prophylactic EFI in cervical cancer are needed.

NRG Oncology/RTOG Consensus Guidelines for Delineation of Clinical Target Volume for Intensity Modulated Pelvic Radiation Therapy in Postoperative Treatment of Endometrial and Cervical Cancer: An Update

PURPOSE

Accurate target definition is critical for the appropriate application of radiation therapy. In 2008, the Radiation Therapy Oncology Group (RTOG) published an international collaborative atlas to define the clinical target volume (CTV) for intensity modulated pelvic radiation therapy in the postoperative treatment of endometrial and cervical cancer. The current project is an updated consensus of CTV definitions, with removal of all references to bony landmarks and inclusion of the para-aortic and inferior obturator nodal regions.

METHODS AND MATERIALS

An international consensus guideline working group discussed modifications of the current atlas and areas of controversy. A document was prepared to assist in contouring definitions. A sample case abdominopelvic computed tomographic image was made available, on which experts contoured targets. Targets were analyzed for consistency of delineation using an expectation-maximization algorithm for simultaneous truth and performance level estimation with kappa statistics as a measure of agreement between observers.

RESULTS

Sixteen participants provided 13 sets of contours. Participants were asked to provide separate contours of the following areas: vaginal cuff, obturator, internal iliac, external iliac, presacral, common iliac, and para-aortic regions. There was substantial agreement for the common iliac region (sensitivity 0.71, specificity 0.981, kappa 0.64), moderate agreement in the external iliac, para-aortic, internal iliac and vaginal cuff regions (sensitivity 0.66, 0.74, 0.62, 0.59; specificity 0.989, 0.966, 0.986, 0.976; kappa 0.60, 0.58, 0.52, 0.47, respectively), and fair agreement in the presacral and obturator regions (sensitivity 0.55, 0.35; specificity 0.986, 0.988; kappa 0.36, 0.21, respectively). A 95% agreement contour was smoothed and a final contour atlas was produced according to consensus.

CONCLUSIONS

Agreement among the participants was most consistent in the common iliac region and least in the presacral and obturator nodal regions. The consensus volumes formed the basis of the updated NRG/RTOG Oncology postoperative atlas. Continued patterns of recurrence research are encouraged to refine these volumes.

Haute Couture or Ready-to-Wear? Tailored Pelvic Radiotherapy for Prostate Cancer Based on Individualized Sentinel Lymph Node Detection

Prostate cancer (PCa) pelvic radiotherapy fields are defined by guidelines that do not consider individual variations in lymphatic drainage. We examined the feasibility of personalized sentinel lymph node (SLN)-based pelvic irradiation in PCa. Among a SLN study of 202 patients, we retrospectively selected 57 patients with a high risk of lymph node involvement. Each single SLN clinical target volume (CTV) was individually segmented and pelvic CTVs were contoured according to Radiation Therapy Oncology Group (RTOG) guidelines. We simulated a radiotherapy plan delivering 46 Gy and calculated the dose received by each SLN. Among a total of 332 abdominal SLNs, 305 pelvic SLNs (beyond the aortic bifurcation) were contoured (mean 5.4/patient). Based on standard guidelines, CTV missed 67 SLNs (22%), mostly at the common iliac level (40 SLNs). The mean distance between iliac vessels and the SLN was 11mm, and despite a 15mm margin around the iliac vessels, 9% of SLNs were not encompassed by the CTV. Moreover, 42 SLNs (63%) did not receive 95% of the prescribed dose. Despite a consensus on contouring guidelines, a significant proportion of SLNs were not included in the pelvic CTV and did not receive the prescribed dose. A tailored approach based on individual SLN detection would avoid underdosing pelvic lymph nodes that potentially contain tumor cells.

Reduction of dose to duodenum with a refined delineation method of Para-aortic region in patients with locally advanced cervical Cancer receiving prophylactic extended-field radiotherapy

Background

To compare irradiation dose to the second and third portions of duodenum (Duo2 and Duo3) with a new refined and old delineation method of para-aortic region for patients with locally advanced cervical cancer (LACC) receiving prophylactic extended-field radiotherapy (EFRT).

Methods

Twenty consecutive patients with LACC were treated with prophylactic EFRT from January 2016 to January 2017 at our institute. Two delineation methods of para-aortic region were designed for each patient, the old delineation method ensured a full coverage of aortic and inferior vena cava, while the right paracaval region above L3 was omitted from CTV in the new delineation method. Patients received a dose of 50.4Gy in 28 fractions for PCTV and a dose of 60.2Gy in 28 fractions for PGTV with volumetric-modulated arc therapy (VMRT). The dose delivered to Duo2 and Duo3 with these two delineation methods were compared.

Results

All treatment plans achieved excellent target volume coverage with 95% of PCTV receiving 50.4Gy and 95% of PGTV receiving 60.2Gy. There was no difference between delineation methods in low dose level (V5, V10, V15, V20, V25) for Duo2 and Duo3. The V30, V35, V40, V45, V50, Dmax, Dmean and D2cc for Duo2 with the new and old delineation methods were 55.76% vs 80.54% (P = 0.009), 34.72% vs 70.91% (P < 0.001), 18.69% vs 55.46% (P < 0.001), 8.20% vs 41.49% (P < 0.001), 1.86% vs 21.60% (P < 0.001), 49.58Gy vs 52.91Gy (P = 0.002), 30.38Gy vs 39.22Gy (P = 0.001) and 37.90Gy vs 48.64Gy (P < 0.001) respectively. For Duo3, the new delineation method achieved significant advantages in V30, V35, V40, V45, V50 and Dmean over the old one (96.82% vs 99.25%, P = 0.021; 89.65% vs 97.21%, P = 0.001; 79.50% vs 93.18%, P < 0.001; 65.63% vs 82.93%, P < 0.001; 43.39% vs 65.60%, P < 0.001; 46.09Gy vs 49.24Gy, P < 0.001), no deference was observed regarding D2cc and Dmax with these two delineation methods.

Conclusion

With the new delineation method of para-aortic area in prophylactic EFRT, significant reduction of irradiation dose to the second and third portions of duodenum in high dose area was obtained. This may further lower the incidence of duodenal toxicity when performing prophylactic EFRT for patients with LACC.

The role of para-aortic nodal irradiation in cervical cancer

The current standard of care for locally advanced cervical cancer is whole pelvis and para-aortic radiation when indicated, delivered concomitantly with chemotherapy and brachytherapy. Para-aortic node involvement is a predictor of survival in locally advanced disease but presence of metastases is difficult to determine because the currently available imaging methods lack enough sensitivity to be able to detect accurately para-aortic metastases when surgical staging is not feasible. The objective of this review is to describe the current status of para-aortic lymph node irradiation in locally advanced cervical cancer. It includes analysis of the diagnostic imaging and surgical approaches for assessment of para-aortic lymph node dissemination, together with indications for radiotherapy and radiotherapeutic techniques.