Effective heart-sparing whole lung irradiation using volumetric modulated arc therapy: a case report

Late cardiovascular disease-related adverse events are one of the most common causes of premature mortality among long-term survivors of childhood cancer. As it is difficult to reduce the heart dose with traditional anteroposterior-posteroanterior field whole lung irradiation for pulmonary metastasis, improved radiation techniques are highly desirable. We report a case treated with whole lung irradiation using volumetric modulated arc therapy.

A 3-year-old Japanese girl with pulmonary metastases of Wilms' tumor received 12 Gy in 8 fractions of whole lung irradiation using volumetric modulated arc therapy. The treatment was well tolerated, and the course was completed as planned without any toxicity. We found statistically significant reduced volumetric modulated arc therapy irradiation doses to organs at risk relative to those of the standard anteroposterior-posteroanterior field technique. The mean heart dose was 8.5 Gy for volumetric modulated arc therapy and 12.3 Gy for the anteroposterior-posteroanterior field. The doses to liver and thyroid were also more favorable with volumetric modulated arc therapy than with the anteroposterior-posteroanterior field technique. We confirmed the dosimetric advantages of volumetric modulated arc therapy over anteroposterior-posteroanterior field in whole lung irradiation in terms of superior normal organ protection.

Effective heart sparing is possible for whole lung irradiation using volumetric modulated arc therapy. Large-scale studies using standardized procedures should be conducted to validate our results.