title: Anaplastic carcinoma following well-differentiated thyroid cancer: etiological considerations.
abstract: Most cases of anaplastic thyroid carcinoma can be pathologically and often historically associated with the presence of low-grade (differentiated) cancer in the thyroid. That radiation therapy to the differentiated tumor plays an etiologic role in the transformation of a differentiated to an undifferentiated tumor has been suggested. If such therapy can be implicated, is there a difference in risk between external radiotherapy or radioactive iodine? Review of the literature discloses that more anaplastic carcinoma of the thyroid develop in patients without a history of prior radiation than in individuals who have received radiation. We report our recent experience with two patients who demonstrated the sequence of well-differentiated followed by anaplastic thyroid cancer subsequent to radiation and review the question.
mesh_terms: D000368:Aged; D002277:Carcinoma / Q000209:etiology* / Q000473:pathology / Q000532:radiotherapy; D006801:Humans; D008297:Male; D009381:Neoplasms, Radiation-Induced; D013964:Thyroid Neoplasms / Q000209:etiology* / Q000473:pathology / Q000532:radiotherapy