Volumetric considerations in radiotherapy for pediatric parameningeal rhabdomyosarcomas

Local control of parameningeal rhabdomyosarcoma: An expert consensus guideline from the International Soft Tissue Sarcoma Consortium (INSTRuCT)

The International Soft Tissue Sarcoma Database Consortium (INSTRuCT) consists of a collaboration between the Children's Oncology Group (COG) Soft Tissue Sarcoma Committee, the European pediatric Soft Tissue Sarcoma Study Group (EpSSG), and the Cooperative Weichteilsarkom Studiengruppe (CWS). As part of the larger initiative of INSTRuCT to provide consensus expert opinions for clinical treatment of pediatric soft tissue sarcoma, we sought to provide updated, evidenced-based consensus guidelines for local treatment of parameningeal rhabdomyosarcoma using both existing literature as well as recommendations from the relevant cooperative group clinical trials. Overall, parameningeal rhabdomyosarcoma represents a distinctly challenging disease to treat, given its location near many critical structures in the head and neck, frequently advanced local presentation, and predilection for local failure. Definitive chemoradiation remains the standard treatment approach for parameningeal rhabdomyosarcoma, with surgery often limited to biopsy or salvage therapy for recurrent disease. In this consensus paper, we specifically discuss consensus guidelines and evidence for definitive local management with radiotherapy, with a focus on imaging for radiotherapy planning, dose and timing of radiation, approach for nodal irradiation, various radiation techniques, including proton therapy, and the limited role of surgical resection.

45 GyRBE for group III orbital embryonal rhabdomyosarcoma

Purpose: Despite widespread concerns of radiotherapy toxicity in children with head and neck tumors, recent Children's Oncology Group (COG) findings suggest that the use of 45 Gy results in an unacceptably high rate of local recurrences in patients with low-risk orbital rhabdomyosarcoma. We therefore evaluated outcomes in our pediatric patients who received 45 GyRBE using proton therapy. Material and methods: To assess disease control and toxicity, we reviewed the medical records of 30 children (≤21 years old) with COG stage 1, group III embryonal orbital rhabdomyosarcoma enrolled on a prospective outcome study and treated with proton therapy between 2007 and 2018. Results: Median age at the time of radiation was 4.8 years old. Twenty-one and nine patients received ifosfamide- and cyclophosphamide-based chemotherapy according to their respective cooperative group regimens. Median duration between the start of induction chemotherapy and radiation was 12 weeks. Two patients had a complete response to induction chemotherapy and two had stable disease. Twenty-six patients had a partial response to induction chemotherapy, with a median volume reduction of 66%. With a median follow-up of 4.0 years (range, 0.5-9.5 years), we observed 1 local failure 6 months following treatment in a patient who had a partial response to cyclosphophomide-based induction chemotherapy. The 5-year local control, progression-free survival, and overall survival rates were 97%, 97%, and 100%, respectively. Serious late toxicities included 18 patients with cataracts, 4 with exposure keratoconjunctivitis resulting in permanently reduced visual acuity, and 1 with chronic sinusitis. Conclusion: 45 GyRBE offers effective local control for most patients with group III orbital rhabdomyosarcoma. The delivery of proton therapy to the postinduction tumor volume plus a small margin can mitigate early- and intermediate-term toxicity, but side effects still occur and long-term data are needed to demonstrate the dosimetric advantage of proton therapy.

Patterns of Failure in Pediatric Rhabdomyosarcoma After Proton Therapy

PURPOSE

To report on the patterns of failure in children with rhabdomyosarcoma treated with proton therapy.

PATIENTS AND METHODS

Between February 2007 and November 2013, 66 children with a median age of 4.1 years (range, 0.6-15.3 years) diagnosed with nonmetastatic rhabdomyosarcoma were treated with proton therapy. Clinical target volume 1 was defined as the prechemotherapy tumor plus a 1-cm anatomically constrained margin. Clinical target volume 2 was defined as the postchemotherapy tumor (or tumor bed) plus a 0.5-cm anatomically constrained margin, further expanded to encompass potential pathways of spread, including soft tissue infiltrated with tumor at diagnosis.

RESULTS

Of the 66 children, 11 developed locally progressive disease at a median of 16 months (range, 14-32 months), for an actuarial 2-year local control rate of 88%. Among the children who progressed, median age and tumor size at diagnosis were 6.7 years (range, 0.6-16 years) and 6 cm (range, 2-8 cm), respectively. Of the recurrences, 64% and 36% were embryonal and alveolar, respectively. Disease progression was observed in 7 (64%) parameningeal, 2 (18%) head and neck (other), and 2 (18%) bladder/prostate subsites. At diagnosis, 8 of 11 patients who developed a recurrence were Intergroup Rhabdomyosarcoma Study stage 3, and all 11 were group III. Of the relapses, 100% (11 of 11) were confirmed as in-field within the composite 95% isodose line. One of the 11 patients (9%) developed a new simultaneous regional nodal recurrence outside of the previously treated radiation field.

CONCLUSION

Early data suggest that the sharp dosimetric gradient associated with proton therapy is not associated with an increased risk of marginal failure. Routine use of a 0.5- to 1-cm clinical target volume 1/2 margin with highly conformal proton therapy does not compromise local control in children diagnosed with rhabdomyosarcoma with unfavorable risk features.

Decline of Tumor Vascular Function as Assessed by Dynamic Contrast-Enhanced Magnetic Resonance Imaging Is Associated With Poor Responses to Radiation Therapy and Chemotherapy

PURPOSE

To investigate whether changes in the volume transfer coefficient (K(trans)) in a growing tumor could be used as a surrogate marker for predicting tumor responses to radiation therapy (RT) and chemotherapy (CT).

METHODS AND MATERIALS

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was consecutively performed on tumor-bearing mice, and temporal and spatial changes of K(trans) values were measured along with tumor growth. Tumor responses to RT and CT were studied before and after observed changes in K(trans) values with time.

RESULTS

Dynamic changes with an initial increase and subsequent decline in K(trans) values were found to be associated with tumor growth. When each tumor was divided into core and peripheral regions, the K(trans) decline was greater in core, although neither vascular structure or necrosis could be linked to this spatial difference. Tumor responses to RT were worse if applied after the decline of K(trans), and there was less drug distribution and cell death in the tumor core after CT.

CONCLUSION

The K(trans) value in growing tumors, reflecting the changes of tumor microenvironment and vascular function, is strongly associated with tumor responses to RT and CT and could be a potential surrogate marker for predicting the tumor response to these treatments.

Rhabdomyosarcoma in adults: new perspectives on therapy

OPINION STATEMENT

Rhabdomyosarcoma (RMS) is well known as a pediatric disease. Most of the knowledge, like biology, genetics, and treatments of this disease, comes from studies done in that age group. The two subtypes of RMS, embryonic RMS and alveolar RMS, that affect mainly the pediatric population are well described in the literature and that has had an impact on the improvement in overall survival during the past 20 years. RMS in the adult population has a low incidence, therefor the study of RMS in this group is challenging. Pleomorphic RMS is the subtype that mainly affects adults and its biology and genetics are not yet completely understood and described. The risk factors for this tumor and the differences among adults and children is also poorly understood. The treatments for adults that have RMS are not standardized having an impact on the overall survival. Pleomorphic RMS has, compared to other adult sarcomas, poor overall survival. Adult patients with RMS have poor prognosis. The standardization of treatments for the adult population is necessary as maybe new treatments for this specific group. There are new treatment options that are being studied mostly in pediatrics and young adults. Immunotherapy is currently proposed as an important treatment possibility including different techniques like vaccination, antigen-mediated therapy, and immune checkpoints. Even if we have a better understanding of RMS, there are still unanswered questions. The improvements seen in the pediatric population are encouraging, but there is still the need to enhance better therapies for adults with RMS.

Unusual leptomeningeal dissemination in a child with extracranial metastatic alveolar rhabdomyosarcoma

The authors describe a 6-year-old boy diagnosed with alveolar rhabdomyosarcoma located in the thigh, with distal metastases to lungs, bones, and bone marrow. A very good partial response to first-line chemotherapy was obtained, but the child developed fatal leptomeningeal dissemination immediately after complete resection of the primary tumor. This case demonstrates the rapidity with which leptomeningeal spread of extracranial metastatic alveolar rhabdomyosarcoma can occur and underscores the importance of diagnostic lumbar puncture and brain radiological investigations at diagnosis, even when the tumors are not in the parameningeal location.

The AMORE protocol for advanced-stage and recurrent nonorbital rhabdomyosarcoma in the head-and-neck region of children: a radiation oncology view

PURPOSE

A multidisciplinary approach, consisting of consecutive Ablative Surgery, MOld technique with afterloading brachytherapy and immediate surgical REconstruction (AMORE) applied after chemotherapy, was designed for children with rhabdomyosarcoma in the head-and-neck region. Analysis of the first 42 patients was performed.

METHODS AND MATERIALS

After macroscopically radical tumor resection, molds were constructed for each individual to fit into the surgical defect. The molds, made of 5-mm-thick layers of thermoplastic rubber, consisted of different parts. Flexible catheters were positioned between layers. After brachytherapy, the molds were removed. Surgical reconstruction was performed during the same procedure.

RESULTS

Dose to the clinical target volume varied from 40 to 50 Gy for the primary treatment (31 patients) and salvage treatment groups (11 patients). There were 18 females and 24 males treated from 1993 until 2007. Twenty-nine tumors were located in the parameningeal region, and 13 were located in the nonparameningeal region. Patient age at the time of AMORE was 1.2-16.9 years (average, 6.5 years). Follow-up was 0.2-14.5 years (average, >5.5 years). Eleven patients died, 3 with local recurrence only, 6 with local and distant disease, 1 died of distant metastases only, and 1 patient died of a second primary tumor. Overall 5-year survival rates were 70% for the primary treatment group and 82% for the salvage group. Treatment was well tolerated, and acute and late toxicity were mild.

CONCLUSIONS

The AMORE protocol yields good local control and overall survival rates, and side effects are acceptable.

The challenging role of radiation therapy for very young children with rhabdomyosarcoma

PURPOSE

To evaluate local control and toxicity for very young children treated with multimodality therapy for rhabdomyosarcoma (RMS).

METHODS AND MATERIALS

From 1990 to 2004, 20 patients<or=36 months at diagnosis were treated at our institution. Nineteen underwent chemotherapy (CMT), surgery and/or intraoperative high-dose-rate brachytherapy (IOHDR), and external-beam radiation (EBRT). Median age was 17 months. Sites included extremity (7), trunk (5), parameningeal (4), orbit (1), head/neck (1), bladder/prostate (1). Histologies consisted of 10 embryonal (53%) and 9 alveolar/undifferentiated (47%). Ten had delayed gross total resection (GTR) at median time of 17 weeks after the start of CMT, and 8 of these underwent IOHDR. Median interval between start of CMT and EBRT was 18 weeks. Median EBRT dose was 36 Gy. EBRT technique was either intensity-modulated (11), three-dimensional (3), or two-dimensional (5). Functional outcome was assessed for patients alive>or=1 year after diagnosis (15) in terms of mild, moderate, or severe deficits.

RESULTS

Median follow-up was 33 months for survivors and 23 months for all patients. Two-year actuarial local control, event-free survival, disease-specific survival, and overall survival were 84%, 52%, 74%, and 62%, respectively. All patients who began EBRT<or=18 weeks after the start of CMT had their disease controlled locally. Five have mild deficits and 10 have no deficits.

CONCLUSIONS

A reduced dose of 36-Gy EBRT after delayed GTR may maximize local control while minimizing long-term sequelae for very young children with RMS, but unresectable tumors (e.g., parameningeal) require higher doses. Normal-tissue-sparing techniques such as intensity-modulated radiation therapy and IOHDR are encouraged. Local control may be maximized when EBRT begins <or=18 weeks after initiation of CMT, but further study is warranted. Longer follow-up is required to determine the full extent of late effects.

Intensity-modulated radiotherapy for head-and-neck rhabdomyosarcoma

PURPOSE

To determine the preliminary results of intensity-modulated radiotherapy (IMRT) for head-and-neck rhabdomyosarcoma.

METHODS AND MATERIALS

Twenty-eight patients underwent IMRT as a part of multimodality therapy. Twenty-one tumors were parameningeal, three were orbital, and four were in other sites. The median age was 8 years (range, 1-29 years). Most (89%) had Group III disease. Intracranial extension was present in 71% of parameningeal tumors. A 1.5-cm margin was used, and the median dose was 50.4 Gy (range, 30-55.8 Gy).

RESULTS

The actuarial 3-year survival rate for patients with parameningeal tumors was 65%. The 3-year actuarial freedom from failure rate was 95% locally, 90% in regional nodes, 88% in the central nervous system, and 80% at distant sites. No failures occurred among patients with orbit tumors; a single central nervous system failure occurred in 1 patient with a lip/cheek tumor. Disease-free survival was significantly worse for patients with alveolar histologic features (p = 0.01). Acute radiation toxicity was similar to that reported by the Intergroup Rhabdomyosarcoma Study Group. Late radiation toxicity was recorded and was mild.

CONCLUSION

IMRT with image fusion results in outstanding local control despite the use of a reduced margin. However, survival among patients with alveolar histologic findings or intracranial extension remains unacceptably low.

Amore protocol in pediatric head and neck rhabdomyosarcoma: Descriptive analysis of failure patterns

BACKGROUND

The AMORE protocol is a local treatment for patients with nonorbital pediatric head and neck rhabdomyosarcoma (HNRMS). The objectives of this study were: (1) to assess the adequacy of the concept, and (2) to identify factors associated with relapse.

METHODS

We performed a retrospective multidisciplinary review of 22 children primarily treated according to the AMORE protocol, excluding two children with inadequate imaging data.

RESULTS

Seven patients had a local relapse, six within and one outside the residual tumor area. Five of the six patients with relapse in the residual area had gross total or debulking (incomplete) surgery, suboptimal position of the mold for brachytherapy, or both. In the 15 nonrecurrent cases, four patients had either incomplete surgery or suboptimal mold position. Both surgical and brachytherapeutic factors seem to be associated with relapse.

CONCLUSIONS

AMORE is an adequate concept. More rigid preoperative imaging and intraoperative verification of the brachytherapy mold position might lead to a reduction in the number of local failures.

Update in management of head and neck sarcoma

PURPOSE OF REVIEW

This update addressing head and neck sarcoma presents new data published after January 2003. This new information is presented following review of contemporary management principles established before 2003.

RECENT FINDINGS

The application of advances in molecular and genetic techniques to characterize individual sarcomas has improved classification schemes and hopefully will lead to individually tailored therapy. Maturation and refinements of large tumor registries are permitting more detailed analysis of larger contemporary series of the rare head and neck sarcomas. Improved long-term survival of patients treated for sarcoma in their childhood has allowed study of the morbidity induced by treatment. Novel treatment strategies are under study to decrease morbidity without diminishing the chance for cure.

SUMMARY

Progress in improving the treatment of sarcoma of the head and neck has been slow due to the lack of a large clinical experience with this rare neoplasm. Advances continue and are anticipated to be most striking in the study of genetic mechanisms.