Proton therapy for sarcomas

Dosimetric comparison between proton beam therapy, intensity modulated radiation therapy, and 3D conformal therapy for soft tissue extremity sarcoma

PURPOSE/OBJECTIVES

Proton beam therapy (PBT) may provide a dosimetric advantage in sparing soft tissue and bone for selected patients with extremity soft sarcoma (eSTS). We compared PBT with photons plans generated using intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT).

MATERIALS/METHODS

Seventeen patients previously treated with pencil beam scanning PBT were included in this study. Of these patients, 14 treated with pre-operative 50 Gy in 25 fractions were analyzed. IMRT and 3D-CRT plans were created to compare against the original PBT plans. Dose-volume histogram (DVH) indices were evaluated amongst PBT, IMRT, and 3D plans. Kruskal-Wallis rank sum tests were used to get the statistical significance. A p value smaller than .05 was considered to be statistically significant.

RESULTS

For the clinical target volume (CTV), D2%, D95%, D98%, D_min, D_max, and V50Gy, were assessed. D_min, D1%, D_max, D_mean, V1Gy, V5Gy, and V50Gy were evaluated for the adjacent soft tissue. D1%, D_max, D_mean, and V35-50% were evaluated for bone. All plans met CTV target coverage. The PBT plans delivered less dose to soft tissue and bone. The mean dose to the soft tissue was 2 Gy, 11 Gy, and 13 Gy for PBT, IMRT, and 3D, respectively (p < .001). The mean dose to adjacent bone was 15 Gy, 26 Gy, and 28 Gy for PBT, IMRT, and 3D, respectively (p = .022).

CONCLUSION

PBT plans for selected patients with eSTS demonstrated improved sparing of circumferential soft tissue and adjacent bone compared to IMRT and 3D-CRT. Further evaluation will determine if this improved dosimetry correlates with reduced toxicity and improved quality of life.

Early Experience Using Proton Beam Therapy for Extremity Soft Tissue Sarcoma: A Multicenter Study

Purpose

Proton beam therapy (PBT) may provide an advantage when planning well-selected patients with extremity soft tissue sarcoma (eSTS), specifically for large, anatomically challenging cases. We analyzed our early experience with PBT on toxicity and outcomes.

Materials and Methods

A retrospective study was performed for eSTS treated between June 2016 and October 2020 with pencil beam scanning PBT at 2 institutions. Diagnostic, treatment, and toxicity characteristics were gathered from baseline to last follow-up or death. Wound complications were defined as secondary operations for wound repair (debridement, drainage, skin graft, and muscle flap) or nonoperative management requiring hospitalization. Statistical analysis was performed with R software.

Results

Twenty consecutive patients with a median age 51.5 years (range, 19–78 years) were included. Median follow-up was 13.7 months (range, 1.7–48.1 months). Tumor presentation was primary (n = 17) or recurrent after prior combined modality therapy (n = 3). Tumor location was either lower extremity (n = 16) or upper extremity (n = 4). Radiation was delivered preoperatively in most patients (n = 18). Median pretreatment tumor size was 7.9 cm (range, 1.3 –30.0 cm). The 1-year locoregional control was 100%. Four patients (20%) had developed metastatic disease by end of follow-up. Maximum toxicity for acute dermatitis was grade 2 in 8 patients (40%) and grade 3 in 3 patients (15%). After preoperative radiation and surgical resection, acute wound complications occurred in 6 patients (35%). Tumor size was larger in patients with acute wound complications compared with those without (medians 16 cm, range [12–30.0 cm] vs 6.3 cm, [1.3–14.4 cm], P = .003).

Conclusion

PBT for well selected eSTS cases demonstrated excellent local control and similar acute wound complication rate comparable to historic controls. Long-term follow-up and further dosimetric analyses will provide further insight into potential advantages of PBT in this patient population.

Ewing Sarcoma-Diagnosis, Treatment, Clinical Challenges and Future Perspectives

Ewing sarcoma, a highly aggressive bone and soft-tissue cancer, is considered a prime example of the paradigms of a translocation-positive sarcoma: a genetically rather simple disease with a specific and neomorphic-potential therapeutic target, whose oncogenic role was irrefutably defined decades ago. This is a disease that by definition has micrometastatic disease at diagnosis and a dismal prognosis for patients with macrometastatic or recurrent disease. International collaborations have defined the current standard of care in prospective studies, delivering multiple cycles of systemic therapy combined with local treatment; both are associated with significant morbidity that may result in strong psychological and physical burden for survivors. Nevertheless, the combination of non-directed chemotherapeutics and ever-evolving local modalities nowadays achieve a realistic chance of cure for the majority of patients with Ewing sarcoma. In this review, we focus on the current standard of diagnosis and treatment while attempting to answer some of the most pressing questions in clinical practice. In addition, this review provides scientific answers to clinical phenomena and occasionally defines the resulting translational studies needed to overcome the hurdle of treatment-associated morbidities and, most importantly, non-survival.

Managing axial bone sarcomas in childhood

Introduction: Axial osteosarcoma and Ewing sarcoma are rare, aggressive neoplasms with a worse prognosis than with tumors involving the extremities because they are more likely to be associated with larger tumor volumes, older age, primary metastases, and a poor histological response to chemotherapy. The 5-year OS rates are reportedly in the range of 18-41% for axial osteosarcoma, and 46-64% for Ewing sarcoma.Area covered: The treatment of axial bone tumors is the same as for extremity bone tumors, and includes chemotherapy, surgery and/or radiotherapy.Expert opinion: Local treatment of axial tumors is particularly difficult due to their proximity to neurological and vascular structures, which often makes extensive and en bloc resections impossible without causing significant morbidity. The incidence of local relapse is consequently high, and this is the main issue in the treatment of these tumors. Radiotherapy is an option in the case of surgical resections with close or positive margins, as well as for inoperable tumors. Delivering high doses of RT to the spinal cord can be dangerous. Given the complexity and rarity of these tumors, it is essential for this subset of patients to be treated at selected reference institutions with specific expertise and multidisciplinary skills.

Impact of different treatment techniques for pediatric Ewing sarcoma of the chest wall: IMRT, 3DCPT, and IMPT with/without beam aperture

Purpose

To evaluate the dosimetric differences between photon intensity‐modulated radiation therapy (IMRT) plans, 3D conformal proton therapy (3DCPT), and intensity‐modulated proton therapy (IMPT) plans and to investigate the dosimetric impact of different beam spot size and beam apertures in IMPT for pediatric Ewing sarcoma of the chest wall.

Methods and Materials

Six proton pediatric patients with Ewing sarcoma in the upper, middle, and lower thoracic spine regions as well as upper lumbar spine region were treated with 3DCPT and retrospectively planned with photon IMRT and IMPT nozzles of different beam spot sizes with/without beam apertures. The plan dose distributions were compared both on target conformity and homogeneity, and on organs‐at‐risk (OARs) sparing using QUANTEC metrics of the lung, heart, liver, and kidney. The total integral doses of healthy tissue of all plans were also evaluated.

Results

Target conformity and homogeneity indices are generally better for the IMPT plans with beam aperture. Doses to the lung, heart, and liver for all patients are substantially lower with the 3DPT and IMPT plans than those of IMRT plans. In the IMPT plans with large spot without beam aperture, some OAR doses are higher than those of 3DCPT plans. The integral dose of each photon IMRT plan ranged from 2 to 4.3 times of proton plans.

Conclusion

Compared to IMRT, proton therapy delivers significant lower dose to almost all OARs and much lower healthy tissue integral dose. Compared to 3DCPT, IMPT with small beam spot size or using beam aperture has better dose conformity to the target.

Spindle Cell Sarcoma of the Maxilla: A Rare Entity, Case Report, and Review of the Literature

Spindle cell sarcoma (SCS) is a malignancy, with the most recent Surveillance, Epidemiology, and End Results (SEER) data citing a total of 250 reported cases occurring in the head and neck. Of these cases, none originated in the maxillofacial hard tissue. To the best of our knowledge, only 2 cases of primary osseous SCS of the maxillofacial region have been reported. These cases were not accounted for in the SEER data. The diagnosis of SCS requires its differentiation from other sarcomas and spindle cell neoplasms. Therefore, a comprehensive review to reinforce its inclusion in oral and maxillofacial surgeons' differential diagnosis for osseous neoplastic pathology is desired. In the present case report, we have described a maxillary SCS in a patient with an initial diagnosis of a spindle cell lesion of uncertain biologic behavior. We reviewed the data for SCS, including the epidemiologic data, diagnostic challenges, clinical and radiographic presentations, prognostic indicators, and treatment.

Dosimetric advantages of proton beam therapy compared to intensity-modulated radiation therapy for retroperitoneal chordoma

Retroperitoneal chordomas are exceedingly rare and account for less than 5% of all primary bone malignancies. Their etiology remains unknown. We report a rare case of an extravertebral chordoma of the retroperitoneum in a 71-year-old man treated with surgical resection and post-operative spot-scanning proton beam therapy. We describe how to safely treat a retroperitoneal target to a prescription dose over 70 Gy (relative biological effectiveness) with spot-scanning proton beam therapy and also report a dosimetric comparison of spot-scanning proton beam therapy versus intensity-modulated radiation therapy. This case not only highlights a rare diagnosis of an extravertebral retroperitoneal chordoma but it also draws attention to the dosimetric advantages of proton beam therapy and illustrates a promising radiotherapeutic option for retroperitoneal targets.

[Radiotherapy after tumour prostheses-status, indication, coordination]

BACKGROUND

Patients with complex tumour prostheses often require radiotherapy or radiochemotherapy.

OBJECTIVES

Possible tumour diagnoses, indications, planning and therapy procedures, and prognosis of radiotherapy in the context of an interdisciplinary treatment for bone sarcomas are reviewed, including interactions of metal prostheses with radiation and possible subsequent complications.

METHODS

Literature search, summary of personal experience.

RESULTS

Complex prosthetic procedures are usually applied to patients suffering from Ewing sarcoma or osteosarcoma. In patients with Ewing sarcoma, radiotherapy is an integral part of multimodal treatment, while in patients with osteosarcoma radiotherapy is indicated in special situations. Planning and implementation of radiotherapy treatment can be impaired by metal implants within the target volume (artefacts in the planning computerized tomography, interaction of metal with the therapeutic beam). However, it is-to our knowledge-a point of debate whether radiotherapy after implantation of a prosthesis could impair healing or prosthesis fixation to bone. The data available in the literature suggest that prostheses implanted after radiotherapy entail a higher rate of complications. Multidisciplinary treatment improves the prognosis for these patients markedly.

CONCLUSIONS

Patients with sarcomas of the bone undergoing interdisciplinary treatment consisting of surgery, radiotherapy and chemotherapy have a favourable prognosis and an acceptable functionality of the limb can be expected.

Chemotherapy in head and neck osteosarcoma: Adjuvant chemotherapy improves overall survival

BACKGROUND

Osteosarcoma is an aggressive bone malignancy presenting uncommonly in head and neck sites. Surgery is mainstay in treatment. However; trials show an improved survival with addition of chemotherapy in the treatment of extremity osteosarcoma. The head and neck osteosarcomas(HNOs) were excluded in these trials because of atypical presentation and disease course. Further; sufficient numbers were not possible for a trial. We present the largest retrospective study from single institute investigating the role of chemotherapy in the management of HNOs.

PATIENTS AND METHODS

The retrospective cohort of HNOs treated from 2007 to 2015 of a tertiary hospital were charted. The therapeutic and prognostic factors were analyzed for overall survival(OS), disease free survival(DFS), local control(LC) and metastasis(MT) in univariate and multivariate analysis. The minimum and median period of follow up was 12months and 56.04months respectively.

RESULTS

There was a total of 157 patients definitively treated with surgery in the time period. 7 patients had positive margins and all were maxillary or skull base tumors. The multivariate cox regression showed significance of tumor site(p=0.034), margin status (p=0.006), chemotherapy(p=0.025), histological subtype(p=0.012) as predictors of overall survival. The margin status(p=0.002), Radiotherapy(p=0.005) were significant predictors for local recurrence. The age and histology subtype(p=0.058) were borderline significant predictors of metastasis(p=0.065). The KM method for OS of different chemotherapy groups(p=0.013), and survival with and without chemotherapy(p=0.007) was significant. The OS was significantly better with adjuvant chemotherapy among various treatment plans(p=0.034).

CONCLUSION

Adjuvant chemotherapy improved OS while adjuvant radiotherapy improved local control of HNOs.

Surgery Combined with Radiotherapy to Treat Spinal Tumors: A Review of Published Reports

Spinal tumors result in high morbidity and a high rate of lower limb paralysis. Both surgical therapy and radiation therapy (RT) are used to treat spinal tumors; however, how best to combine these two therapies to maximize the benefits and minimize the risks is still being debated. It is also difficult to decide the optimal timing, course and dose of RT, especially in pregnant women and children. The aim of this review is to assist surgeons who are dealing with spinal tumors by providing comprehensive information about advanced techniques for administering RT with greater precision and safety, and about the impact of various ways of combining surgery and RT on therapeutic outcomes. We here review published reports about treating spinal tumors with a combination of these two forms of therapy and attempt to draw appropriate conclusions concerning selection of optimal treatment protocols. Our conclusion is that postoperative radiotherapy, especially with high-precision, low-dose and multiple fractions, and brachytherapy are promising therapies to combined with surgery.

Radiation promotes colorectal cancer initiation and progression by inducing senescence-associated inflammatory responses

Proton radiotherapy is becoming more common since protons induce more precise DNA damage at the tumor site with reduced side effects to adjacent normal tissues. However, the long-term biological effects of proton irradiation in cancer initiation compared to conventional photon irradiation are poorly characterized. In this study, using a human familial adenomatous polyposis syndrome susceptible mouse model, we show that whole body irradiation with protons are more effective in inducing senescence-associated inflammatory responses (SIR) which are involved in colon cancer initiation and progression. After proton irradiation, a subset of SIR genes (Troy, Sox17, Opg, Faim2, Lpo, Tlr2 and Ptges) and a gene known to be involved in invasiveness (Plat), along with the senescence associated gene (P19Arf) are markedly increased. Following these changes loss of Casein kinase Iα (CKIα) and induction of chronic DNA damage and TP53 mutations are increased compared to x-ray irradiation. Proton irradiation also increases the number of colonic polyps, carcinomas and invasive adenocarcinomas. Pretreatment with the non-steroidal anti-inflammatory drug, CDDO-EA, reduces proton irradiation associated SIR and tumorigenesis. Thus, exposure to proton irradiation elicits significant changes in colorectal cancer initiation and progression that can be mitigated using CDDO-EA.