Radiation Therapy for Thyroid Cancer. When is Radiation Therapy indicated in Thyroid Cancer of Follicular or Parafollicular Cell Origin?

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1 When is Radiation Therapy indicated in Thyroid Cancer of Follicular or Parafollicular Cell Origin? Jeanne Marie Quivey MD FACR October 200 Radiation Therapy for Thyroid Cancer Radioactive 3- I (RAI) External Beam Radiation Therapy (EBRT) Conventional Beam 3D Conformal Therapy IMRT- Intensity modulated RT IGRT- Image guided RT Thyroid Cancer: RAI UCSF RAI Ablation. Post Thyroidectomy ablation of residual normal thyroid tissue 2. Long term management of pts with regional or distant CA which is Iodine avid 3. Possible use after redifferentiating agents such as Rosiglitazone/ Acutane. J Clin Endocrinol and Metab: 99, 87:

2 What to do if Surgery and the Magic Bullet is not adequate for treatment of Locoregional Disease? (?Smart Bomb) Brierley et al PMH 729 pts Diff Thyroid cancer (no recurrent pts) Prospective treatment database at PMS Prospective National Thyroid Cancer Cooperative Study Group after 985 Clinical Endocrinology.(2005) 63:48-427, Brierley J et al. Brierley PMS Results Three time periods: pts pts pts The later cohorts tended to have younger pts with smaller more differentiated lesions. There were more papillary lesions in the later cohort. Clinical Endocrinology.(2005) 63:48-427, Brierley J et al. Brierley PMS Results EBRT given to 90 pts with papillary histology and microscopic residual while 64 similar patients did not. LRFR improved with EBRT after RAI (0 yr 95.9% vs 85.4%) but CSS not. LRFR and CSS were improved in 47pts > 60y/o and T4 disease with no gross residual after surgery. Clinical Endocrinology.(2005) 63:48-427, Brierley J et al. 2

3 EBRT- Brierley PMH EBRT- Brierley PMH EBRT Technique Dose of XRT was Gy in 20 Fx over 4 weeks. The daily dose of XRT is high. Since 2002 the policy at PMH is to use adjuvant XRT to the thyroid bed and total thyroidectomy and RAI only in pts with gross extrathyroidal extension T4A especially if > 45 y/o. Clinical Endocrinology.(2005) 63:48-427, Brierley J et al. Acute side effects Late side effects Mucositis of larynx, trachea and esophagus Skin erythema and desquamation Dry mouth Airway edema Dry mouth (depends on radiation technique and prior RAI) Fibrosis of the soft tissues of the neck Possible esophageal stenosis Possible vascular injury 3

4 Thyroid IMRT DVH IMRT Thyroid IMRT: Isodose UCSF Thyroid IMRT Treated between 998 and 2007: Patient Characteristics 38 Patients (22 with recurrence post prior definitive surgery +/- RAI) 22 with gross residual tumor 8 with microscopic residual 3 with mediastinal disease 4 also with known distant mets (6 anaplastic, 7 recurrent, papillary) 4

5 Pre and Post Radiation Therapy for Recurrence of Thyroid Cancer # of Recurrence Pre Radiation Post Radiation Central Neck Disection Thyroidectomy Modified Radical Neck Radical Neck Thyroid Completion I Months from Radiation PET scan Mediastinal Recurrence.00 Local Regional Progression Cummulative Proportion All Papillary Ca Papillary Ca with High Risk Histology Medullary Anaplastic Radiation Plan Recurrence below Port Months from Start of Radiation Therapy 5

6 Time to Progression of Distant Mets All Papillary Ca Papillary Ca with High Risk Histology Medullary Anaplastic Cummulative Proportion Months from Start of Radiation Therapy Overall Survival Conclusions.00 Cummulative Proportion All Papillary Ca Papillary Ca with High Risk Feat Medullary Anaplastic EBRT of clear benefit for LRC in pts with T4a EBRT improves DSS for pts > 60y/o with T4a disease EBRT with IMRT allows excellent dose distribution and minimal late effects (in our series only seen in pts with LR) Months from Start of Radiation Therapy 6

7 Image Guided Adaptive Radiation Therapy UCSF Thyroid risk ratios Megavoltage Conebeam CT Evaluate patient position Adjust as needed Evaluate changes in patient anatomy over time Examine effects on dose Examine dose delivered to targets and critical structures Decide when to replan Alter plan based on delivered dose J Clin Endocrinol and Metab: 99, 87: Thyroid IMRT: Pathology Papillary Anaplastic Follicular and Hurthle Cell Poorly Differentiated Medullary Insular