Late toxicity and outcomes following radiation therapy for chest wall sarcomas in pediatric patients

Abstract

Purpose: To investigate the contribution of radiation therapy to acute and late toxicity in pediatric chest wall sarcoma patients and evaluate dosimetric correlates of higher incidence toxicities such as scoliosis and pneumonitis.

Methods and materials: The data from 23 consecutively treated pediatric patients with chest wall sarcomas of various histologies (desmoid, Ewing, rhabdomyosarcoma, nonrhabdomyosarcoma-soft tissue sarcomas) were reviewed to evaluate the relationship between end-organ radiation dose, clinical factors, and the risk of subsequent late effects (scoliosis, pneumonitis). Cobb angles were used to quantify the extent of scoliosis. Doses to the spine and lung were calculated from the radiation treatment plan.

Results: The range of scoliosis identified on follow-up imaging ranged from -47.6 to 64° (median, 2.95°). No relationship was identified between either radiation dose to the ipsilateral or contralateral vertebral body or tumor size and the degree or direction of scoliosis. The extent of surgical resection and number and location of resected ribs affected the extent of scoliosis. The dominant predictor of extent of scoliosis at long-term follow-up was the extent of scoliosis following surgical resection. Radiation pneumonitis was uncommon and was not correlated with mean dose or volume of lung receiving 24 Gy; however, 1 of 3 surviving patients who received whole pleural surface radiation therapy developed significant restrictive lung disease.

Conclusions: Acute and late radiation therapy-associated toxicities in pediatric chest wall sarcoma patients are modest. The degree of scoliosis following resection is a function of the extent of resection and of the number and location of ribs resected, and the degree of scoliosis at the last follow-up visit is a function of the extent of scoliosis following surgery. Differential radiation therapy dose across the vertebral body does not increase the degree of scoliosis. Severe restrictive pulmonary disease is a late complication of survivors after whole pleural surface radiation therapy.

Figure 1.

Pre- and Post-Radiotherapy Cobb Angle Measurements

Figure 2.

Representative Whole Pleural Surface Intensity-modulated Radiotherapy Plan from a Patient with Ewing Sarcoma.

Figure 3.

Degree of Scoliosis (degrees) at Diagnosis and Absolute Change in Scoliosis (degrees) by Number of Ribs Removed and Extent of Resection.

Figure 4.

Relationship between Scoliosis and Vertebral Body Dose. A) Scoliosis at last follow-up visit as a function of the dose to the ipsilateral vertebral body (relative to tumor), B) Scoliosis at last follow-up visit as a function of the dose to the contralateral vertebral body (relative to tumor), C) Scoliosis at last follow-up visit as a function of the ipsilateral:contralateral vertebral body dose, D) Change in scoliosis from diagnosis to last-follow-up visit as a function of the ipsilateral:contralateral vertebral body dose.

Figure 5.

Change in Scoliosis (degrees) from Diagnosis by Initial Degree of Scoliosis Post-resection.