Radiation Oncology/CSI

• McGill; 2006 PMID 16330119 -- "A simple technique for craniospinal radiotherapy in the supine position." (Parker WA, Radiother Oncol. 2006 Feb;78(2):217-22. Epub 2005 Dec 5.)
  • Supine position, using CT sim

Thyroid

• Hypothyroidism is one of the earliest late side effects of craniospinal irradiation (CSI), and second most common (after growth hormone disturbances)
• Prevalence of hypothyroidism is 40-80% after CSI
• There is also an increased risk of thyroid cancer, possibly with doses as low as 1 Gy

• Milan; 2007 (1998-2001) PMID 17601681 -- "Thyroid-stimulating hormone suppression for protection against hypothyroidism due to craniospinal irradiation for childhood medulloblastoma/primitive neuroectodermal tumor." (Massimino M, Int J Radiat Oncol Biol Phys. 2007 Oct 1;69(2):404-10. Epub 2007 Jul 2.)
  • Prospective. 37 children with medulloblastoma/PNET. Thyroid function evaluation pre and post treatment. Given L-thyroxine at suppressive doses q3 days, starting 14 day prior CSI till end of treatment. Median F/U 7 years for alive patients
  • Outcome: 8 children adequate TSH suppression, 17 children not. Hypothyroid-free survival rate: adequate TSH suppression 70% vs. not adequate TSH suppression 20% (SS)
  • Conclusion: TSH suppression had a protective effect during CSI