Biologic considerations and operative strategy in papillary thyroid carcinoma: arguments against the routine performance of total thyroidectomy.

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.