Teaching CaseCorrelation of long-term pulmonary injury with radiation dose distribution in childhood cancer survivors
Introduction
Advances in cancer treatment have resulted in almost 80 percent of children surviving at least 5 years after cancer diagnosis.1 Childhood cancer survivors are 8.6 times more likely to die from pulmonary complications when compared with the general population.2 Pneumonitis and pulmonary fibrosis are known sequelae of pulmonary radiation therapy (XRT) during childhood. In many instances, the presentation may be subclinical, apparent only on incidental chest radiographs or pulmonary function tests. Pulmonary injury may first become apparent shortly after XRT or it may appear years later.
Here we report on 2 patients with XRT-induced pulmonary fibrosis and we describe a technique for correlating radiographic changes of XRT-induced lung injury to dose distribution. We also describe the evolution of lung changes with time and its relationship with radiation dose and location.
Section snippets
Case 1
A 3-year-old Asian female presented with cough. Imaging studies showed a large mass in her left lung. She underwent biopsy and was diagnosed with type III pleuropulmonary blastoma. She received combination chemotherapy with vincristine, actinomycin D, and cyclophosphamide alternating with cisplatin and doxorubicin. After 5 cycles of chemotherapy, there was significant decrease in size of the mass and she underwent gross total surgical resection. Due to the presence of microscopic residual
Case 2
A 16-year-old Asian male presented with recurrent Ewing sarcoma of the left posterior ninth rib with erosion into the left pleural space. He received chemotherapy with ifosfamide, etoposide, topotecan, and cyclophosphamide followed by left ninth rib resection. Due to tumor erosion into the pleural space, he was referred for XRT. The initial GTV included the left lung. A modified clinical target volume was created from an inner and outer margin based upon the left lung contour. A 1-cm margin was
Discussion
XRT is an effective anti-cancer agent. During delivery of XRT to the tumor site, the surrounding normal tissue is exposed to radiation as well. The amount of XRT that can be delivered is limited by normal tissue tolerance. Radiation pneumonitis occurs within 6-12 months of receiving XRT. Several parameters such as V20 (volume of lung getting at least 20 Gy), mean lung dose, and normal tissue complication probability have been identified in adults that variably correlate with pneumonitis.3, 4, 5
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Cited by (1)
Towards an improvement of the quality of life after radiotherapy in children
2015, Bulletin du Cancer
Conflicts of interest: None.