Reasons cited for the routine performance of total
thyroidectomy in patients with
papillary thyroid carcinoma include: fear of multicentric neoplastic foci causing local recurrence and death; risk of anaplastic transformation of unresected multifocal microscopic
carcinoma; toxicity of high-dose radioactive
iodine to ablate normal thyroid remnants; and lack of reliable criteria for grading
malignancy and identifying patients at high risk. However, autopsy studies have detected microscopic foci of
papillary thyroid cancer as incidental findings in up to 24% of patients dead of other diseases. The prevalence of anaplastic transformation of
papillary thyroid carcinoma as determined from reports in the literature is less than 1%. A retrospective investigation of 90 patients with
papillary thyroid carcinoma derived from the Swedish National
Cancer Registry showed no complications from radioiodine ablation of postoperative thyroid remnants in 45 patients. Retrospective analysis of the
DNA content of
tumors at the time of the initial operation showed a significant difference between a group of 10 patients who died of recurrent and metastatic
papillary thyroid carcinoma and a group of 16 patients alive at least 10 years after operation despite distant
metastases or recurrent
cancer in the thyroid bed and/or cervical lymph nodes. The risk of permanent
hypoparathyroidism is higher in patients after total
thyroidectomy without apparent improvement in survival rates when compared with less extensive resections. Therefore it is proposed that the criteria for total
thyroidectomy in patients with
papillary thyroid carcinoma be limited to:
tumors that clinically involve both lobes of the thyroid gland, extracapsular spread of
cancer requiring enbloc resection, and reoperations where
scarring prevents accurate delineation of the extent of the
tumor. By differentiating patients at high risk for death from
papillary thyroid carcinoma from patients at low risk, the measurement of
DNA content may decrease the need for routine total
thyroidectomy.