Effective Management of Sacral Stress Fractures in Gastric Cancer: Iliosacral Screw Fixation Following a Type 3 Hemipelvectomy.

Metastatic pelvic tumors pose a significant challenge in oncologic orthopedics due to their complex management and the high potential for postoperative complications. This case study discusses a 75-year-old male with a sacral stress fracture following a type 3 internal hemipelvectomy for a metastatic lesion from gastric cancer in the left pubic bone. Initial conservative treatments failed to yield satisfactory improvement, leading to surgical intervention. Open reduction and internal fixation with an iliosacral screw, despite complications, significantly alleviated pain and improved mobility. This case underscores the difficulty in diagnosing sacral stress fractures versus metastatic lesions and highlights the effectiveness of iliosacral screw fixation in managing postoperative sacral stress fractures. It emphasizes the procedure's role in providing early pain relief and enhancing daily activity levels. Additionally, it points out the importance of addressing altered bone metabolism in the postoperative care of patients with metastatic pelvic tumors. This contributes to the literature by stressing the incidence of sacral stress fractures as a critical, though often overlooked, complication and demonstrating the benefits of iliosacral screw fixation in such scenarios for better recovery and quality of life.

Multiscale spatial relationship-based model for predicting bladder wall dose in pelvic radiotherapy.

PURPOSE: This research aimed to develop a prediction model to assess bladder wall dosimetry during radiotherapy for patients with pelvic tumors, thereby facilitating the refinement and evaluation of radiotherapy treatment plans to mitigate bladder toxicity. METHODS: Radiotherapy treatment plans of 49 rectal cancer patients and 45 gynecologic cancer patients were collected, and multiple linear regression analyses were used to generate prediction models for bladder wall dose parameters ( V 10 - 45 G y ( c m 3 ) ${V_{10 - 45Gy\ }}( {{\mathrm{c}}{{\mathrm{m}}^3}} )$ , D m e a n ( Gy ) ${D_{mean}}( {{\mathrm{Gy}}} )$ ). These models were based on the multiscale spatial relationship between the planning target volume (PTV) and the bladder or bladder wall. The proportion of bladder or bladder wall volume overlapped by the different distance expansions of the PTV was used as an indicator of the multiscale spatial relationship. The accuracy of these models was verified in a cohort of 12 new patients, with further refinement of radiotherapy treatment plans using the predicted values as optimization parameters. Model accuracy was assessed using root mean square error (RMSE) and mean percentage error (MPE). RESULTS: Models derived from individual disease data outperformed those derived from combined datasets. Predicted bladder wall dose parameters were accurate, with the majority of initial calculated values for new patients falling within the 95% confidence interval of the model predictions. There was a robust correlation between the predicted and actual dose metrics, with a correlation coefficient of 0.943. Using the predicted values to optimize treatment plans significantly reduced bladder wall dose (p < $\ < \ $ 0.001), with bladder wall D mean ( G y ) ${D_{{\mathrm{mean}}}}( {Gy} )$ and V 10 - 45 G y ( c m 3 ) ${V_{10 - 45Gy\ }}( {{\mathrm{c}}{{\mathrm{m}}^3}} )$ decreasing by 2.27±0.80 Gy (5.8%±1.8%) and 2.96±2.05 cm3 (7.9%±5.4%), respectively. CONCLUSION: The formulated prediction model provides a valuable tool for predicting and minimizing bladder wall dose and for optimizing and evaluating radiotherapy treatment plans for pelvic tumor patients. This approach holds promise for reducing bladder toxicity and potentially improving patient outcomes.

Monitoring of Interfractional Proton Range Verification and Dosimetric Impact Based on Daily CBCT for Pediatric Patients with Pelvic Tumors.

(1) Background: Synthetic CT images of the pelvis were generated from daily CBCT images to monitor changes in water equivalent path length (WEPL) and determine the dosimetric impact of anatomy changes along the proton beam's path; (2) Methods: Ten pediatric patients with pelvic tumors treated using proton therapy with daily CBCT were included. The original planning CT was deformed to the same-day CBCT to generate synthetic CT images for WEPL comparison and dosimetric evaluation; (3) Results: WEPL changes of 20 proton fields at the distal edge of the CTV ranged from 0.1 to 12 mm with a median of 2.5 mm, and 75th percentile of 5.1 mm for (the original CT-rescanned CT) and ranged from 0.3 to 10.1 mm with a median of 2.45 mm and 75th percentile of 4.8 mm for (the original CT-synthetic CT). The dosimetric impact was due to proton range pullback or overshoot, which led to reduced coverage in CTV Dmin averaging 12.1% and 11.3% in the rescanned and synthetic CT verification plans, respectively; (4) Conclusions: The study demonstrated that synthetic CT generated by deforming the original planning CT to daily CBCT can be used to quantify proton range changes and predict adverse dosimetric scenarios without the need for excessive rescanned CT scans during large interfractional variations in adaptive proton therapy of pediatric pelvic tumors.

3D printing for patient-specific implants in musculoskeletal oncology.

Satisfactory results in terms of functional and oncological outcomes can be obtained in sacral and pelvic malignant bone tumors. Preoperative planning, adequate imaging, and a multidisciplinary approach are needed. 3D-printed prostheses have to fulfill several requirements: (i) mechanical stability, (ii) biocompatibility, (iii) implantability, and (iv) diagnostic compatibility. In this review, we highlight current standards in the use of 3D-printed technology for sacropelvic reconstruction.

Imaging of pediatric extragonadal pelvic soft tissue tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper.

The most common pediatric extragonadal pelvic cancers include germ cell tumors, sacrococcygeal teratomas, and rhabdomyosarcomas (arising from the urinary bladder, prostate, paratesticular tissues, vagina, uterus, and perineum). This paper describes the radiological and nuclear medicine features of these entities and provides consensus-based recommendations for the assessment at diagnosis, during, and after treatment.

Robotic-assisted resection of deep pelvic schwannoma.

INTRODUCTION: Schwannomas are a group of well differentiated benign tumors originating from the Schwann cells of the peripheral nervous system. Their localization in the pelvis is very rare. Schwannomas with expansive growth can cause wide neurologic symptoms or oppression of pelvic organs. CASE REPORT: The authors present a case study of a 60-year-old woman with a large, symptomatic deep pelvic schwannoma. The patient underwent robotic-assisted surgery resulting in complete tumor extirpation. The patient's postoperative course was uneventful with a total of two hospitalization days. The diagnosis of a schwannoma was confirmed by histopathologic analysis. At 11-month follow-up surveillance the patient did not present any neurological deficit or other symptoms. CONCLUSION: Robotic-assisted surgery allows safe and effective surgical treatment in difficult-to-access anatomical areas. Magnetic resonance imaging is required for preoperative imaging of neurogenic tumors. Histological verification is not recommended in cases where evidence of a schwannoma is found. Multidisciplinary cooperation of a dedicated team experienced in minimally invasive pelvic surgery is necessary.

[Perioperative augmented reality technology in surgical treatment of locally advanced recurrent rectal cancer]. / Perioperatsionnoe primenenie tekhnologii dopolnennoi real'nosti v khirurgicheskom lechenii bol'nogo mestnorasprostranennym lokoregionarnym retsidivom raka pryamoi kishki.

Rectal cancer occupies the leading position among cancers, and incidence of locally advanced recurrences is still high despite comprehensive treatment. Combined resections are usually associated with high perioperative risks. These procedures are technically complex interventions requiring further improvement. Virtual reality technology in surgical treatment of locally advanced rectal cancer recurrence has not been widely discussed. The authors present multidisciplinary construction of the matched topographic-anatomical virtual model and virtual planning of the combined surgical intervention. Intraoperative use of augmented reality allowed specifying topographic and anatomical features of surgical area, level of vascular ligation, localization of tumor fixation points and resection borders. These data ensured safety and quality of resection. Further research of augmented reality technology and improvement of its technical aspects will improve the results of surgical treatment of patients with locally advanced pelvic tumors and recurrences.

[Fast track recovery protocols for extended pelvic surgery]. / Protokoly uskorennogo vyzdorovleniya pri rasshirenno-kombinirovannykh operatsiyakh na organakh malogo taza.

OBJECTIVE: To compare the immediate results of extended pelvic surgery before and after introduction of standardized fast track surgery (FTS) protocol into routine clinical practice. MATERIAL AND METHODS: The study included 111 patients with pelvic tumors who underwent extended pelvic surgery. The control group included 59 patients whose perioperative management implied traditional approaches (2018-2019), the main group - 52 patients with FTS protocol (2020-2021). Age, BMI and ECOG status were similar. In the main group, females (90.4% vs. 74.6%; p=0.046), patients with recurrent (46.2% vs. 22.0%; p=0.009) and complicated tumors (26.9% vs. 11.9%; p=0.054) prevailed. Obstructive resection without anastomosis was less common in the main group (28.8% vs. 47.5%; p=0.068). RESULTS: Surgery time was higher (319±125 min vs. 236±79 min, p<0.001) in the main group, but blood loss (238±154 ml vs. 282±150 ml, p=0.029) and incidence of blood transfusions (23.1% vs. 42.4%, p=0.043) were lower. Moreover, complications (36.6% vs. 54.3%; p=0.086), mild complications (Clavien-Dindo class I-II) (11.6% vs. 28.8%; p=0.034) and local infectious complications (19.2% vs. 42.4%; p=0.009) were less common in the main group. Two patients died in the control group due to sepsis following colonic anastomosis and bladder suture failure, respectively. Postoperative hospital-stay was similar (14±9.1 days vs. 14.4±9 days; p=0.89). CONCLUSION: FTS protocol is possible and safe in patients with locally advanced and recurrent malignant pelvic tumors. This approach reduces blood loss, the number of blood transfusions and risk of postoperative infections.

Safety and Efficacy of Palliative Radiotherapy (25 Gy × 5 Fractions) for Symptomatic Pelvic Tumors.

BACKGROUND/AIM: Palliative radiotherapy is one of the effective treatments for pelvic tumors with bleeding or pain. In this study, we evaluated the safety and efficacy of palliative radiotherapy (RT) for symptomatic pelvic tumors when delivered as 25 Gy in 5 fractions. PATIENTS AND METHODS: We retrospectively analyzed 34 patients (gynecological cancer: n=14, rectal cancer: n=5, metastatic pelvic bone tumor: n=7, metastatic pelvic lymph node tumor: n=5, synovial sarcoma of the pelvis: n=1, prostate cancer: n=1, and urothelial cancer: n=1), who were treated between July 2016 and July 2021. The symptoms were bleeding in 16 patients, pain in 17 patients, and both bleeding and pain in 1 patient. The hemostatic effect of RT was evaluated with pre- and post-treatment hemoglobin (Hb) values. If the Hb levels reached a nadir and increased thereafter, we considered that there is a hemostatic response. The pain was evaluated with a numerical rating scale (NRS) and treatment response was defined as a decrease in NRS. RESULTS: Their median follow-up period was 4 months. A hemostatic response was observed in 82% of patients (14 of 17 patients). A pain relief response was observed in 78% of patients (14 of 18 patients). Acute adverse effects (AEs) included grade 1 diarrhea (n=3), grade 1 dermatitis (n=1) and grade 1 urinary frequency (n=1); late AEs have not been observed so far. CONCLUSION: 25 Gy of palliative RT in 5 fractions seems to be safe and effective for symptomatic pelvic tumors, similar to conventional palliative RT schedules.

Construction of a predictive model for radiation proctitis after radiotherapy for female pelvic tumors based on machine learning. / åŸºäºŽæœºå™¨å­¦ä¹ æž„å»ºå¥³æ€§ç›†è ”è‚¿ç˜¤æ”¾å°„æ²»ç–—åŽæ”¾å°„æ€§ç›´è‚ ç‚Žçš„é¢„æµ‹æ¨¡åž‹.

OBJECTIVES: Radiation therapy is a main method for female pelvic malignancies, which can cause some adverse reactions, such as radiation proctitis (RP). The incidence of RP is highly positively correlated with radiation dose. There is an urgent need for a scientific method to accurately predict the occurrence of RP to help doctors make clinical decisions. In this study, based on the clinical data of female pelvic tumor patients and dosimetric parameters of radiotherapy, the random forest method was used to screen the hub features related to the occurrence of RP, and then a machine learning algorithm was used to construct a risk prediction model for the occurrence of RP, in order to provide technical support and theoretical basis for the prediction and prevention of RP. METHODS: A total of 100 female patients with pelvic tumors, who received static three-dimensional conformal intensity-modulated radiation therapy in the Department of Radiation Oncology of the Affiliated Hospital of Xiangnan University from January 2019 to December 2020, were retrospectively collected, and their clinically relevant data and radiotherapy planning system data were collected. During radiotherapy and 18 months after radiotherapy, 35 cases developed RP (RP group), and the remaining 65 cases had no RP (non-RP group). The clinical and dosimetric characteristics of patients were ranked by the importance of random forest algorithm, and the independent prognostic characteristics associated with the occurrence of RP were selected for machine learning modeling. A total of 6 machine learning algorithms including support vector machines, random forests, logistic regression, lightweight gradient boosting machines, Gaussian naïve Bayes, and adaptive enhancement were used to build models. The performance of the model was evaluated by the area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and F1 score. Finally, the random forest model was determined as the prediction model, and the calibration curve and decision curve of the prediction model were drawn to evaluate the accuracy and clinical benefit of the model. RESULTS: The parameters for random forest prediction model in the training set were as follow: AUC, 1.000, accuracy, 0.988, sensitivity, 1.000, specificity, 1.000, positive predictive value, 1.000, negative predictive value, 0.981, and F1 score, 1.000. In validation set, AUC was 0.713, accuracy was 0.640, sensitivity was 0.618, specificity was 0.822, positive predictive value was 0.500, negative predictive value was 0.656, and F1 score was 0.440. Random forest showed high predictive performance. Moreover, the Brief of the calibration curve for the prediction model was 0.178, the prediction accuracy was high, and the decision curve showed that the prediction model could benefit clinically. CONCLUSIONS: Based on the clinical and dosimetric parameters for the female pelvic tumor patients, the prediction model of radiation proctitis constructed by random forest algorithm has high predictive ability and strong clinical usability.

Deep learning-based low-dose CT for adaptive radiotherapy of abdominal and pelvic tumors.

The shape and position of abdominal and pelvic organs change greatly during radiotherapy, so image-guided radiation therapy (IGRT) is urgently needed. The world's first integrated CT-linac platform, equipped with fan beam CT (FBCT), can provide a diagnostic-quality FBCT for achieve adaptive radiotherapy (ART). However, CT scans will bring the risk of excessive scanning radiation dose. Reducing the tube current of the FBCT system can reduce the scanning dose, but it will lead to serious noise and artifacts in the reconstructed images. In this study, we proposed a deep learning method, Content-Noise Cycle-Consistent Generative Adversarial Network (CNCycle-GAN), to improve the image quality and CT value accuracy of low-dose FBCT images to meet the requirements of adaptive radiotherapy. We selected 76 patients with abdominal and pelvic tumors who received radiation therapy. The patients received one low-dose CT scan and one normal-dose CT scan in IGRT mode during different fractions of radiotherapy. The normal dose CT images (NDCT) and low dose CT images (LDCT) of 70 patients were used for network training, and the remaining 6 patients were used to validate the performance of the network. The quality of low-dose CT images after network restoration (RCT) were evaluated in three aspects: image quality, automatic delineation performance and dose calculation accuracy. Taking NDCT images as a reference, RCT images reduced MAE from 34.34 ± 5.91 to 20.25 ± 4.27, PSNR increased from 34.08 ± 1.49 to 37.23 ± 2.63, and SSIM increased from 0.92 ± 0.08 to 0.94 ± 0.07. The P value is less than 0.01 of the above performance indicators indicated that the difference were statistically significant. The Dice similarity coefficients (DCS) between the automatic delineation results of organs at risk such as bladder, femoral heads, and rectum on RCT and the results of manual delineation by doctors both reached 0.98. In terms of dose calculation accuracy, compared with the automatic planning based on LDCT, the difference in dose distribution between the automatic planning based on RCT and the automatic planning based on NDCT were smaller. Therefore, based on the integrated CT-linac platform, combined with deep learning technology, it provides clinical feasibility for the realization of low-dose FBCT adaptive radiotherapy for abdominal and pelvic tumors.

Acetabular reconstruction with total hip replacement and femoral head autograft following pelvic resection of malignant bone tumour: A case report.

INTRODUCTION: Pelvic tumors greatly impact survival and quality of life of the patient. Reconstruction following resection of neoplasms involving the acetabulum remains one of the most challenging procedures for orthopaedic surgeons. We reported an 18-year-old female with Hodgkin's lymphoma of the left iliac wing. PRESENTATION OF CASE: A 18-year-old female presented left hip pain since one year before admission. Pelvis X-ray demonstrated lytic lesion on the left iliac crest with moth-eaten pattern. However, the contrast-enhanced MRI showed the true extent of the tumour which engulfed the iliac crest and extended to the anterior border of the acetabulum. The acetabulum was reconstructed using femoral head autograft and total hip replacement. At six months of follow-up, CT scan of the pelvis demonstrated no tumour. No complications occurred during 14 months of follow-up. However, the patient died 28 months post surgery. DISCUSSION: In pelvic sarcomas, the utilization of this technique remains limited, as the complex anatomy and the bulk of tumour growth often limits the choice of what procedure can be conducted. Reconstruction techniques have also advanced, albeit difficult and laden with complications, especially when the lesion involves the acetabulum. CONCLUSIONS: The choice of implant for pelvic resection in the developing country remains challenging due to the high cost of implants. However, in cases of pelvic sarcomas, the utilization of this technique remains limited, as the complex anatomy and the bulk of tumour growth often limits the choice of what procedure can be conducted. Reconstruction techniques have also advanced, albeit difficult and laden with complications, especially when the lesion involves the acetabulum.

Two Cases of Pelvic Diffuse Large B-Cell Lymphoma.

Primary diffuse large B-cell lymphoma presenting as an extranodal site in the pelvis is rare and can mimic a gynecological malignancy. Although management for diffuse large B-cell lymphoma is standardized and curative, prognosis depends on timely diagnosis and therapy. Diagnosis can be challenging as patients lack classical symptoms of fever, night sweats, weight loss, and lymphadenopathy associated with lymphoma. A multidisciplinary approach is recommended to diagnose and treat judiciously. In this article, we present cases of 2 females who presented with pelvic masses with initial suspicion of a gynecological malignancy but were ultimately diagnosed as diffuse large B-cell lymphoma of the pelvis and managed accordingly.

Leaving half the acetabulum in pelvic resections improves hip function. Is there a need to revisit conventional pelvic resections?

BACKGROUND: Conventional periacetabular pelvic resections are associated with poor functional outcomes. Resections through surgical corridors beyond the conventional margins may be helpful in retaining greater function without compromising the oncological margins. METHODS: The study included a retrospective review of 82 cases of pelvic resections for pelvic tumors. Outcomes of acetabulum preservation (Group A) were compared with complete acetabular resection (Group B). Also, we compared outcomes of Type I + half resections (Group 1) with Type I + II resections (Group 2), and Type III + half resections (Group 3) with Type II + III resections (Group 4). RESULTS: Group A (n = 44) had significantly better functional outcome than Group B (n = 38) with average MSTS93 score 22.3 versus 20.1 and average HHS 91.3 versus 82.5 (p < 0.001). Group 1 (n = 14) and Group 2 (n = 12) had similar functional outcomes (mean MSTS93 score 22.07 vs. 21.58 [p = 0.597] and mean HHS 90.37 vs. 86.51 [p = 0.205]). Group 3 (n = 11) had significantly better functional outcome than Group 4 (n = 17), with mean MSTS93 score 22.8 versus 19.7 (p < 0.001) and mean HHS 92.3 versus 80.1 (p < 0.001). Oncological outcomes were similar among the groups. CONCLUSION: Transacetabular pelvic resections provide functional benefit over conventional resections without compromising oncological margins. There is a need to revisit and revise the pelvic resection planes.

Application of 18F-FDG PET-CT Simulation Localization in Radiotherapy of Recurrent Abdominal and Pelvic Tumors / 肿瘤防治研究

Objective To investigate the clinical application value of 18F-FDG PET-CT simulation localization in radiotherapy of recurrent abdominal and pelvic tumors. Methods 18F-FDG PET-CT was used to simulate positioning 38 patients with abdominal and pelvic tumors who relapsed after treatment.Based on both CT images and 18F-FDG PRT-CT, we drew up a systemic treatment plan and outlined the radiotherapy target area, and then compared the differences between the two methods. Results In 38 patients, 21.1%(3/8) of patients were found to have distal metastases outside the pelvic and abdominal cavity, and changed the systemic treatment plan.The radiotherapy target was altered in 34(89.5%) patients.The mean value of GTVPET-CT was 118.14cm3and the mean value of GTVCT was 148.53cm3(P=0.044). Conclusion For patients with recurrent abdominal and pelvic tumors, 18F-FDG PET-CT simulation localization treatment improves tumor re-staging, changes the integrated therapy for some patients, and makes the target area of radiotherapy more accurate.

Clinical-Deep Neural Network and Clinical-Radiomics Nomograms for Predicting the Intraoperative Massive Blood Loss of Pelvic and Sacral Tumors.

BACKGROUND: Patients with pelvic and sacral tumors are prone to massive blood loss (MBL) during surgery, which may endanger their lives. PURPOSES: This study aimed to determine the feasibility of using deep neural network (DNN) and radiomics nomogram (RN) based on 3D computed tomography (CT) features and clinical characteristics to predict the intraoperative MBL of pelvic and sacral tumors. MATERIALS AND METHODS: This single-center retrospective analysis included 810 patients with pelvic and sacral tumors. 1316 CT and CT enhanced radiomics features were extracted. RN1 and RN2 were constructed by random grouping and time node grouping, respectively. The DNN models were constructed for comparison with RN. Clinical factors associated with the MBL were also evaluated. The area under the receiver operating characteristic curve (AUC) and accuracy (ACC) were used to evaluate different models. RESULTS: Radscore, tumor type, tumor location, and sex were significant predictors of the MBL of pelvic and sacral tumors (P < 0.05), of which radscore (OR, ranging from 2.109 to 4.706, P < 0.001) was the most important. The clinical-DNN and clinical-RN performed better than DNN and RN. The best-performing clinical-DNN model based on CT features exhibited an AUC of 0.92 and an ACC of 0.97 in the training set, and an AUC of 0.92 and an ACC of 0.75 in the validation set. CONCLUSIONS: The clinical-DNN and clinical-RN had good performance in predicting the MBL of pelvic and sacral tumors, which could be used for clinical decision-making.

3D-Printed Titanium Custom-Made Prostheses in Reconstruction after Pelvic Tumor Resection: Indications and Results in a Series of 14 Patients at 42 Months of Average Follow-Up.

Wide resection is currently considered the mainstay treatment for primary bone tumors. When the tumor is located in anatomically complex segments, 3D-Printed Titanium Custom-Made Prostheses (3DPTCMP) are possible reconstructive solutions. The aim of the present paper is to analyze indications, results and complications of a series of 14 patients who underwent pelvis reconstruction with 3DPTCMP after tumor removal from January 2015 to December 2019. Chondrosarcoma was the main histology; indications were tumors located in the acetabular area without enough residual bone to support a cup with an iliac stem, and tumors located near the sacrum-iliac joint. The margins were wide in 12 cases, and marginal and intralesional in one case each. In three cases, resection also included the sacrum-iliac joint, so a spine stabilization was performed and linked to the pelvic prosthesis; The average MSTS score was 46.3%; the 5-year local recurrence-free survival was 85.7%. Wound dehiscences were the main complication, resolved with multiple debridements; nevertheless, prosthesis removal was necessary in one case. Currently, the 3DPTCMP is an effective resource for reconstruction after resection of tumors located in the pelvis. Further studies are necessary to value long-term results; more strategies are necessary to try to reduce the infection rate and improve osteointegration.

Patient-Specific Implants for Pelvic Tumor Resections.

Introduction Limb salvage surgery for periacetabular malignancies is technically demanding and associated with a considerable likelihood of postoperative complications and surgical revision. Reconstruction using custom-made implants represents the treatment of choice. This study was conducted to analyze treatment outcomes of custom-made implants in a single orthopaedic tumor center. Patients and Methods Twenty patients with a histologically verified periacetabular malignancy and a median follow up time of 5 (1-17) years were included. Results The median number of revision surgeries per patient was 1.5 (0-7). Complications were dislocations in 3 patients, aseptic loosening in 4 patients, deep infections in 9 patients, thromboembolic events in 5 patients and sciatic nerve lesions in 4 patients. Overall survival was 77% after one year, 69% after two years and 46% after five years. Median Harris Hip Score was 81 (37-92) points at last follow up. Conclusion Although internal hemipelvectomy and reconstruction using custom-made implants is linked with a high risk of postoperative complications, good functional outcomes can be regularly achieved. This information may help treating surgeons to find adequate indications, as eligible patients need to be critically selected and integrated into the decision-making process.

Bilateral metallic hip implants: Are avoidance sectors necessary for pelvic VMAT treatments?

PURPOSE: Metallic hip implants (MHI) are common in elderly patients. For pelvic cancers radiotherapy, conventional approaches consist of MHI avoidance during treatment planning, which leads, especially in case of bilateral MHI, to a decreased quality or increased complexity of the treatment plan. The aim of this study is to investigate the necessity of using avoidance sectors (AvSe) using a 2-arcs coplanar pelvic volumetric modulated arc-therapy (VMAT) planning. METHODS: We evaluated: (1) The dose calculation error of a static 6MV open beam traversing a MHI; (2) The magnitude of an error's decrease within the planning target volume (PTV) for a 360° VMAT treatment without AvSe as compared to the static open beam; (3) The dosimetric influence of MHI misalignment generated by patient's repositioning rolls during image-guided radiotherapy (IGRT). RESULTS: (1) In the static 6MV beam configuration, for distances between 0.5cm and 6cm from the MHI, the median (maximum, number of points) dose calculation error was -1.55% (-2.5%, 11); (2) Compared to the static open beam, in the 360° VMAT treatment without AvSe a simulated error was decreased by a factor of 4.4/2.4 (median/minimum); (3) MHI anterior-posterior misalignment exceeding 0.6cm, resulted in error at PTV surface of >2%. CONCLUSIONS: A standard 2 coplanar arcs 360° VMAT treatment, with dedicated artifact reduction algorithms applied, decreased the error of static beam traversing MHI, in patients presenting a bilateral MHI and might be used to treat the pelvic region without MHI avoidance.