Conformal therapy for pediatric sarcomas

Limited Margin Radiation Therapy for Children and Young Adults With Ewing Sarcoma Achieves High Rates of Local Tumor Control

PURPOSE

To determine the rate of local failure using focal conformal, limited margin radiation therapy (RT) and dose escalation for tumors ≥8 cm (greatest dimension at diagnosis) in children and young adults with Ewing sarcoma (EWS).

METHODS AND MATERIALS

Eligible patients with EWS were treated on a phase 2 institutional trial of focal conformal, limited margin RT using conformal or intensity modulated techniques. The treatment volume incorporated a 1-cm constrained margin around the gross tumor. Unresected tumors, <8 cm at diagnosis, received a standard dose of 55.8 Gy and tumors ≥8 cm, an escalated dose to 64.8 Gy. Patients with microscopic residual disease after resection received adjuvant RT to 50.4 Gy. Adjuvant brachytherapy was permitted in selected patients.

RESULTS

Forty-five patients were enrolled: 26 with localized and 19 with metastatic disease. Median (range) age, tumor size, and follow-up were 13.0 years (2.9-24.7 years), 9.0 cm (2.4-17.0 cm), and 54.5 months (1.9-122.2 months), respectively. All patients received systemic chemotherapy. The median (range) RT dose for all patients was 56.1 Gy (45-65.5 Gy). Seventeen patients received adjuvant, 16 standard-dose, and 12 escalated-dose RT. Failures included 1 local, 10 distant, and 1 local/distant. The estimated 10-year cumulative incidence of local failure was 4.4% ± 3.1%, with no statistical difference seen between RT treatment groups and no local failures in the escalated-dose RT treatment group.

CONCLUSIONS

Treatment with focal conformal, limited margin RT, including dose escalation for larger tumors, provides favorable local tumor control in EWS.

Proton beam therapy: a fad or a new standard of care

PURPOSE OF REVIEW

Newer methods and advances in radiation therapy promise to reduce the risk of complications in children who require irradiation. They have secured the role of radiation therapy in the treatment of a variety of pediatric central nervous system and solid tumors and for young patients enrolled on clinical trials.

RECENT FINDINGS

Proton therapy is the latest advancement in radiation therapy. Its availability is increasing as new centers are built throughout the United States. Pediatric specialists should understand that proton therapy is in its pioneering stage of development and that advantages have not been quantitatively demonstrated. Proton therapy clearly reduces collateral radiation dose to normal tissue when compared with photon (X-ray)-based methods of irradiation and has the potential to selectively and safely escalate dose to high-risk tumors; however, research results are lacking in both of these areas, leading to some confusion among pediatric specialists with regard to indications and the need to refer patients for this limited resource and expensive form of radiation therapy.

SUMMARY

This review highlights a number of issues surrounding proton therapy in children and supports the use of proton therapy in clinical trials.

Incidence and correlates of radiation dermatitis in children and adolescents receiving radiation therapy for the treatment of paediatric sarcomas

AIMS

To investigate the relationship between the maximum grade of skin toxicity, radiation dose and clinical variables in children receiving treatment for sarcomas involving the bone and soft tissue.

MATERIALS AND METHODS

Between January 2003 and July 2006, 82 patients with musculoskeletal tumours on an Institutional Review Board (IRB)-approved prospective study at St. Jude Children's Research Hospital received three-dimensional conformal or intensity-modulated radiation therapy for local tumour control. Radiation dermatitis was graded according to the National Cancer Institute's Common Toxicity Criteria version 2.0 during and after radiation therapy. The dose to the skin was calculated for each patient from the radiation treatment plan.

RESULTS

The radiation doses delivered to the primary tumour ranged from 4140 to 7020cGy, with a mean dose of 5040cGy. The maximum recorded grade of skin toxicity was: grade 0: seven patients (8.6%); grade 1: 26 patients (31.7%); grade 2: 37 patients (45.1%); grade 3: 10 patients (12.2%); grade 4: two patients (2.4%). A significant association for increased grade of skin toxicity was observed between dose (P<0.01), volume of skin treated above 4000cGy (P=0.03), use of a bolus (P<0.01), Caucasian race (P<0.01) and related pain (P<0.01).

CONCLUSIONS

These findings suggest that the delivered dose, use of a bolus, the volume treated, and race may be used in the clinical setting to predict patients at risk for skin toxicity. Alterations in treatment technique and early therapeutic intervention may help to reduce or eliminate radiation-induced skin side-effects and associated pain.

Preliminary results from a prospective study using limited margin radiotherapy in pediatric and young adult patients with high-grade nonrhabdomyosarcoma soft-tissue sarcoma

PURPOSE

To demonstrate the safety and efficacy of limited margin radiotherapy in the local control of pediatric and young adult patients with high-grade nonrhabdomyosarcoma soft tissue sarcoma (NRSTS).

METHODS AND MATERIALS

Pediatric patients with high-grade NRSTS requiring radiation were treated on an institutional review board approved prospective institutional study of conformal/intensity-modulated/interstitial brachytherapy using a 2-cm anatomically constrained margin.

RESULTS

A total of 32 patients (median age, 15.3 years; range, 2-22 years) received adjuvant (27 patients) or definitive (5 patients) irradiation. With a median follow-up of 32 months, the 3-year cumulative incidence of local failure was 3.7% for patients undergoing irradiation after surgical resection. Four patients experienced local failure; the mean dose to the volume of recurrence was >or=97% of the prescribed dose.

CONCLUSIONS

Delivery of limited margin radiotherapy using external beam or brachytherapy provides a high rate of local tumor control without marginal failure. Further follow-up is required to determine whether normal tissue effects are minimized using this approach.

Valgus and varus deformity after wide-local excision, brachytherapy and external beam irradiation in two children with lower extremity synovial cell sarcoma: case report

BACKGROUND

Limb-salvage is a primary objective in the management of extremity soft-tissue sarcoma in adults and children. Wide-local excision combined with radiation therapy is effective in achieving local tumor control with acceptable morbidity and good functional outcomes for most patients.

CASE PRESENTATION

Two cases of deformity after wide-local excision, brachytherapy and external beam irradiation for lower-extremity synovial cell sarcoma are presented and discussed to highlight contributing factors, time course of radiation effects and orthopedic management. In an effort to spare normal tissues from the long-term effects of radiation therapy, more focal irradiation techniques have been applied to patients with musculoskeletal tumors including brachytherapy and conformal radiation therapy. As illustrated in this report, the use of these techniques results in the asymmetric irradiation of growth plates and contributes to the development of valgus or varus deformity and leg-length discrepancies.

CONCLUSIONS

Despite good functional outcomes, progressive deformity in both patients required epiphysiodesis more than 3 years after initial management. There is a dearth of information related to the effects of radiation therapy on the musculoskeletal system in children. Because limb-sparing approaches are to be highlighted in the next generation of cooperative group protocols for children with musculoskeletal tumors, documentation of the effects of surgery and radiation therapy will lead to improved decision making in the selection of the best treatment approach and in the follow-up of these patients.

Novel techniques in the delivery of radiation in pediatric oncology

The field of radiation oncology continues to develop at a rapid pace, due to concurrent progress in high speed computing, improved sensitivity in diagnostic imaging (both anatomic and physiologic), and the introduction of rational new therapeutics built on solid radiobiologic principles. These innovations will become critically important in the field of pediatric oncology, as they will allow for an increased therapeutic ratio in the developing child. Maximizing the benefit of lower dose radiation through the use of radiation modifiers (hypoxic cell sensitizers, signal transduction pathway inhibitors, concurrent chemotherapy), increasing the tolerance of normal tissues (radioprotectors) and tailoring the target area more closely to the desired critical tissues (IMRT, functional simulation with PET and MRS, radiolabeled monoclonal antibodies) will lessen the short and long term toxicity of radiation and increase its effectiveness.