Dose–Effect Relationships for Femoral Fractures After Multimodality Limb-Sparing Therapy of Soft-Tissue Sarcomas of the Proximal Lower Extremity

Toxicity, normal tissue and dose-volume planning parameters for radiotherapy in soft tissue sarcoma of the extremities: A systematic review of the literature

BACKGROUND

Patients with soft tissue sarcoma of the extremities (STSE) are left with high incidence of toxicities after Radiotherapy (RT). Understanding the normal tissue dose relationship with the development of long-term toxicities may enable better RT planning in order to reduce treatment toxicities for STSE. This systematic review of the literature aims at reporting the incidence of acute and late toxicities and identifying RT delineation guidance the normal tissues structures and dose-volume parameters for STSE.

METHODS

A literature search of PUBMED-MEDLINE for studies that reported data on RT toxicity outcomes, delineation guidelines and dose-volume parameters for STSE from 2000 to 2022. Data has been tabulated and reported.

RESULTS

Thirty of 586 papers were selected after exclusion criteria. External beam RT prescriptions ranged from 30 to 72 Gy. The majority of studies reported the use of Intensity Modulated RT (IMRT) (27%). Neo-adjuvant RT was used in 40%. The highest long-term toxicities were subcutaneous and lymphoedema, reported when delivering 3DCRT. IMRT had a lower incidence of toxicities. Normal tissue outlining such as weight-bearing bones, skin and subcutaneous tissue, corridor and neurovascular bundle was recommended in 6 studies. Nine studies recommended the use of dose-volume constraints, but only one recommended evidence-based dose-volume constraints.

CONCLUSION

Although the literature is replete with toxicity reports, there is a lack of evidence-based guidance on normal tissue and dose-volume parameters and strategies to reduce the normal tissues irradiation when optimising RT plans for STSE are poor compared to other tumour sites.

Radiation Therapy for Soft Tissue Sarcoma

Radiation therapy is an integral component of local management with oncologic resection for soft tissue sarcoma. Radiotherapy is indicated in patients at an increased risk of local recurrence so that improved local control may be achieved. Sequencing of radiotherapy and resection should be determined by multidisciplinary input before treatment initiation. For most patients, preoperative delivery of radiation therapy is preferred. In patients initially thought to be at low risk for local recurrence and found to have unexpected adverse pathologic features at resection, postoperative radiation therapy is indicated. The use of radiation therapy for retroperitoneal sarcoma is controversial; when used, preoperative delivery of radiation is recommended.

Treatment of Radiation-Associated Fractures: A Critical Analysis Review

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Fractures that result from radiation-induced bone damage are a recognized adverse effect of radiation therapy (RT).

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The mechanisms of damage from RT are thought to be related to impaired vascularity, aberrations in osteoclast and osteoblast-mediated bone turnover, and compromise of cortical and trabecular microarchitecture.

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Treatment of radiation-associated fractures is challenging, with rates of delayed union and nonunion of >50%.

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Fracture management strategies, each with its own profile of risks and benefits, include prophylactic intramedullary nailing of long bones, open reduction and internal fixation with adjunctive iliac crest or vascularized fibular grafting, and endoprosthetic reconstruction.

Femoral fracture in primary soft-tissue sarcoma of the thigh treated with radiation therapy: indications for prophylactic intramedullary nail

INTRODUCTION

Post-radiation fractures of the femur (PRF) are difficult to treat and are associated with a high risk of delayed union and non-union. We report a series of patients affected by soft tissue sarcoma (STS) of the thigh, treated with limb-sparing surgery and perioperative radiotherapy (RT), to analyse post-radiotherapy femur fracture (FF) rate and its management.

MATERIAL AND METHODS

547 patients treated with surgery and RT for a deep primary STS of the thigh were included. "Periosteal stripping" and "bone tangential resection" were performed in case of tumor invasion. In the case of complete bone involvement, the patient received its complete resection and econstruction.

RESULTS

Twenty-three (4.3%) patients underwent surgical procedures involving periosteum and cortical bone. In 11 (2.0%) patients a bone resection was required because of massive bone involvement. Six out of these 11 (54.5%) patients developed major complications (infection and aseptic loosening). At the time of STS excision, 11 patients (2.0%) underwent prophylactic intramedullary nailing (PIN). PRF occurred in 15 patients (3.0%) at a median follow up of 52 months (range 3-151). Among patients who developed PRF, three were treated with a prosthesis (no complications) and eight nailing (7/8, 87.5% did not heal and developed a non-union).

CONCLUSIONS

Given the potentially devastating complication of a PRF, PIN should be considered. We suggest prophylactic IM nail in patients at higher risk the time of STS excision. In other cases, IM nail can be postponed in the following years considering the prognosis.

Alterations in femoral neck strength following pelvic irradiation. A finite element analysis of simulated eccentric forces using bone density data derived from CT

BACKGROUND AND PURPOSE

Radiotherapy is known to produce long-term skeletal complications. We aim to evaluate the biomechanical effect on femoral neck bone from hypothetical eccentric loads on pre- and post-radiotherapy CT-images for patients treated for rectal cancer.

MATERIAL AND METHODS

Pre- and post-radiotherapy CT-images of rectal cancer from 10 patients were selected randomly. The cortical and trabecular bone was segmented by hand. The biomechanical simulations of 4 eccentric loads and one load aligned with the femoral neck axis were completed using finite element analysis (FEA) in both pre- and post-patient models.

RESULTS

A comparative statistical study was completed of pre- and post-radiotherapy patient models of stress and displacement factors. Significant differences were found in eccentric loads in both factors. Natural load has a significant difference in stress, but no differences were found for displacements. The absolute difference in eccentric load applied to the anterior area location on the same patient implies from 5.3% to 40.5% of the stress yield values reported in previous studies.

CONCLUSIONS

Loads applied to the anterior area of the femoral head must be considered in fracture simulations because the percentage of yield stress of pre- and post-irradiated bones shows a significant biomechanical change.

Postradiation Fractures after Combined Modality Treatment in Extremity Soft Tissue Sarcomas

Soft tissue sarcoma (STS) of the extremities is typically treated with limb-sparing surgery and radiation therapy; with this treatment approach, high local control rates can be achieved. However, postradiation bone fractures, fractures occurring in the prior radiation field with minimal or no trauma, are a serious late complication that occurs in 2–22% of patients who receive surgery and radiation for STS. Multiple risk factors for sustaining a postradiation fracture exist, including high radiation dose, female sex, periosteal stripping, older age, femur location, and chemotherapy administration. The treatment of these pathological fractures can be difficult, with complications including delayed union, nonunion, and infection posing particular challenges. Here, we review the mechanisms, risk factors, and treatment challenges associated with postradiation fractures in STS patients.

[Pelvic irradiation and hematopoietic toxicity: A review of the literature]

Pelvic bone marrow is the site of nearly 50% of total hematopoiesis. Radiation therapy of pelvic lymph node areas, and cancers located near the bony structures of the pelvis, exposes to hematological toxicity in the range of 30 to 70%. This toxicity depends on many factors, including the presence or absence of concomitant chemotherapy and its type, the volume of irradiated bone, the received doses, or the initial hematopoietic reserve. Intensity modulated radiation therapy allows the optimisation of dose deposit on at risk organs while providing optimal coverage of target volumes. However, this suggests that dose constraints should be known precisely to limit the incidence of radiation side effects. This literature review focuses firstly on pelvic lymph node areas and bony volumes nearby, then on the effects of irradiation on bone marrow and the current dosimetric constraints resulting from it, and finally on hematological toxicities by carcinologic location and progress in reducing these toxicities.

Femoral Fracture in Primary Soft Tissue Sarcoma Treated with Intensity-Modulated Radiation Therapy with and Without Dose Constraints

BACKGROUND

We previously reported that the cumulative risk of femoral fracture in patients treated with intensity-modulated radiation therapy (IMRT) for thigh and groin soft tissue sarcoma (STS) is low. In the current study, we sought to evaluate the effect of radiation dose constraints on the rate of femoral fracture in a more contemporary cohort.

METHODS

All patients treated with IMRT for STS of the thigh or groin from 2004 to 2016 were included (n = 145). Beginning in 2011, radiation dose was constrained to a mean dose of < 37 Gy, volume of bone receiving ≥ 40 Gy (V40Gy) < 64%, and maximum dose < 59 Gy to limit the dose to the femur.

RESULTS

Sixty-one patients were treated before dose constraints were implemented, and 84 patients were treated after. Median follow-up for patients treated before and after constraints were implemented was 6.1 and 5.7 years, respectively, and the two groups were demographically and clinically similar. On univariate analysis, the 5-year cumulative incidence of femoral fracture among patients treated with and without dose constraints was 1.8% (95% confidence interval [CI] 0.3-12.2%) versus 7.4% (95% CI 3.1-17.6%) [p = 0.11, p = non-significant, respectively]. On multivariable analysis, only age  ≥ 60 years was significantly associated with increased risk of fracture.

CONCLUSIONS

The risk of femoral fracture after IMRT for STS of the thigh/groin is low, and with the implementation of radiation dose constraints, the risk is < 2%. Although longer follow-up is needed, our results support the utilization of extremity sarcoma IMRT-specific dose constraints for fracture prevention.

Long-Term Risk of Hip Complications After Radiation Therapy for Prostate Cancer: A Dose-Response Study

Purpose

The aim of the present study was to analyze the long-term incidence of hip complications after external beam radiation therapy compared with age-matched controls from the general population. We also investigated whether there were any dose-response associations.

Methods and materials

A total of 349 patients with prostate cancer treated to curative dose with external beam radiation therapy between 1997 and 2002 were included in the study. Physical and fractionation-corrected dose-volume descriptors were derived for the femoral heads, pubic bone, and sacrum. Information on skeletal events was collected for the patients and 1661 matched controls through the Prostate Cancer database Sweden. Uni- and multivariable Cox proportional hazard regressions were used to analyze the time to event.

Results

Data from 346 patients were available for analysis. The median mean physical dose and corresponding equivalent 2-Gy/fraction dose (EQD2) to the femoral heads were 35.5 Gy and 28.7 Gy, respectively. The median follow-up time was 16.0 years. During the follow up, 12 hip fractures occurred. Hip osteoarthritis was diagnosed in 36 cases, with 29 cases leading to replacement surgery. No increased risk of hip fractures was found. Hip osteoarthritis was the only event for which a statistically significant difference was found between the irradiated cohort and the controls (cause-specific hazard ratio: 1.56; 95% confidence interval, 1.07-2.26; P = .02). The cumulative incidence of osteoarthritis at 10 years was 8.1% and 4.9% in the irradiated cohort and the controls, respectively. A significant relationship between osteoarthritis and the volume of the femoral head receiving ≥40 Gy (ie, EQD2) was found.

Conclusions

In this study of 346 patients treated with conventional radiation therapy, we found no increased risk of hip fracture but an increased risk of clinically relevant osteoarthritis at long-term follow up. Our results indicate a dose-response relationship between osteoarthritis and the volume of the femoral head receiving an EQD2 dose of ≥40 Gy.

Pelvic Insufficiency Fractures After External Beam Radiation Therapy for Gynecologic Cancers: A Meta-analysis and Meta-regression of 3929 Patients

PURPOSE

To estimate the overall rate, symptomatic proportion, and most common sites of pelvic insufficiency fracture (PIF) after external beam radiation therapy for gynecologic cancers based on posttreatment computed tomography, magnetic resonance imaging, positron emission tomography, or bone scintigraphy.

METHODS AND MATERIALS

A systematic search of databases (PubMed and EMBASE) was performed (CRD42019125679). The pooled summary of overall PIF and the proportion of symptomatic cases were calculated using the random-effects model weighted by the inverse variance. A multivariate meta-regression was performed to evaluate potential sources of heterogeneity regarding PIF fractures.

RESULTS

Twenty-one studies met the inclusion criteria (total 3929 patients). Five hundred four patients developed PIF, translating to an overall rate of 14% (95% confidence interval, 10%-18%, based on 21 studies). Among these cases with PIF, the proportion of symptomatic patients was 61% (95% confidence interval, 52%-69%, based on 14 studies). The total number of PIFs was 704 (mean, 1.72 PIFs per each patient to develop PIF, based on 14 studies). More recent series (P = .0074) and the use of intensity modulated radiation therapy (P = .0299) were associated with lower fracture rates. The most common fracture sites were sacroiliac joint (39.7%), body of the sacrum (33.9%), pubis (13%), lumbar vertebra (7%), iliac bone (2.8%), acetabulum (2.1%), and femoral head/neck (1.5%). The median time to fracture was 7.1 to 19 months after radiation therapy.

CONCLUSIONS

The incidence of PIF after radiation therapy for gynecologic cancers is high (14%), with the majority affecting the sacral bone or joint (73.6%), although this risk appears to be lower with intensity modulated radiation therapy. Posttreatment bone surveillance is warranted in this population because nearly 40% of patients were asymptomatic at the time of PIF diagnosis.

Femoral Fracture in Primary Soft-Tissue Sarcoma of the Thigh and Groin Treated with Intensity-Modulated Radiation Therapy: Observed versus Expected Risk

PURPOSE

This study was designed to compare the observed risk of femoral fracture in primary soft-tissue sarcoma (STS) of the thigh/groin treated with intensity-modulated radiation therapy (IMRT) to expected risk calculated using the Princess Margaret Hospital (PMH) nomogram.

METHODS

Expected femoral fracture risk was calculated by using the PMH nomogram. Cumulative risk of fracture was estimated by using Kaplan-Meier statistics. Prognostic factors were assessed with univariate and multivariate analysis using Cox's stepwise regression.

RESULTS

Between February 2002 and December 2010, 92 consecutive eligible patients were assessed. Median follow-up was 73 months (106 months in surviving patients). IMRT was delivered preoperatively (50 Gy) in 13 (14%) patients and postoperatively in 79 (86%) patients (median dose, 63 Gy; range, 59.4-66.6 Gy). The observed crude risk of fractures was 6.5% compared with 25.6% expected risk from the nomogram; the cumulative risk of fracture using IMRT at 5 years was 6.7% (95% CI 2.8-16.0%). The median time to fracture was 23 months (range, 6.9-88.6). Significant predictors of fracture on univariate analysis were age ≥ 60 years (p = 0.03), tumor location in the anterior thigh (p = 0.008), and periosteal stripping to > 20 cm (p < 0.0001). On multivariate analysis, age ≥ 60 years and periosteal stripping > 20 cm retained significance (p = 0.04 and p = 0.009, respectively).

CONCLUSIONS

In this study, the cumulative risk of femur fracture in patients treated with IMRT (6.7%) is less than the expected risk using the PMH nomogram (25.6%). Established predictors of femur fracture, such as gender, tumor size, and dose of RT, seem to have less impact on fracture risk when using IMRT.

[Normal tissue tolerance to external beam radiation therapy: Bone marrow and cortical bone structures]

In patients undergoing external radiation therapy, bone marrow and cortical bone structures are all often neglected as organs at risk. Still, from increased febrile neutropenia risk in patients undergoing chemoradiation for a pelvic tumour to increased risk of vertebral fracture when undergoing hypofractioned stereotactic radiotherapy of a spinal metastasis, adverse effects are frequent and sometimes serious. This literature review first defines the rules for contouring these structures, then the dose constraints currently recommended. This article focuses first on conventional irradiation or intensity modulation radiotherapy considering classical fractionation. Secondly, it focuses on stereotactic radiotherapy. The considered organs will be haematopoietic structures, and bone cortical structures. Current recommendations are summarised in a table.

[Insufficiency fractures after irradiation therapy - case series]

BACKGROUND

Radiation therapy plays an essential part in modern treatment regimes of musculoskeletal tumors. Nevertheless damage to the surrounding tissue does occur inevitably. Postradiogenic changes of bone are associated with decreased stability and an increased fracture rate. The orthopedic surgeon therefore faces a challenging situation with altered bone metabolism, changes in perfusion and soft tissue problems.

PATIENTS/MATERIAL AND METHODS

We present 3 cases of radiation induced fractures during the treatment of soft tissue tumors, all of which received radiation doses of > 58 Gy. All fractures occurred over 1 year after the exposure to radiation in otherwise uneventful follow ups.

RESULTS

Postoperative follow up showed fracture healing or in the case of the arthroplasty, osseous integration without further complications.

CONCLUSIONS

Radiation doses of ≥ 58 Gy are a major risk factor for pathological fractures in long bones. Regardless of their low incidence, fracture rates between 1,2 and 6,4 % prove their importance. Local tumor control has therefore to be weighed against the resulting decrease in bone quality and stability. Treatment options should always take into consideration the increased risk for complications such as infection, pseudarthroses and wound healing disorders. Our results show that substitution of vitamin D and calcium as well as the the use of reamed intramedullary implants benefits the outcome.

A subtrochanteric femoral fracture 15 years after radiotherapy: a case report

Pathological fracture is a rare but serious complication of radiotherapy. We report on a 44-year-old man who presented with a subtrochanteric femoral fracture 15 years after radiotherapy for a soft-tissue sarcoma in the thigh. We discuss its potential causes, a scoring system to identify high-risk patients for prophylactic intramedullary nailing of the femur, and radiographic signs to identify an impending insufficiency fracture.

Practical radiation oncology for extremity sarcomas

Soft tissue sarcomas are rare cancers. They should be managed by a multidisciplinary team with experience caring for these diverse malignancies. Local control is frequently achieved with a combination of radiation therapy and surgery. This article reviews the data supporting the role of adjuvant radiotherapy in the care of patients with soft tissue sarcoma and describes the side effects of surgery and radiation therapy. Preoperative radiation therapy increases the risk of wound complication from surgery, but has fewer long-term side effects than postoperative radiation therapy. The timing of radiation therapy can be tailored to each patient.