Insular Thyroid Carcinoma: Collective Analysis of Clinicohistologic Prognostic Factors and Treatment Effect with Radioiodine or Radiation Therapy

Abstract

Insular thyroid carcinoma is a distinctive clinicopathologic entity with aggressive behavior and frequent lethal disease. But because it is rare, no single institute has sufficient experience with the clinicopathologic features and treatment effect of radioiodine. A literature review and collective analysis might facilitate patient management. From January 1991 to December 2005, 9 patients with insular thyroid carcinoma were diagnosed in Taipei Veterans General Hospital. Clinicopathologic data were collected for analysis. The English literature about insular carcinoma was searched in Medline. Patients with detailed descriptions of treatment and followup were enrolled. Clinicopathologic features, rate of lymph node and distant metastasis, and prognostic factors were analyzed. Seventy-three of 486 patients collected from 23 articles with detailed description of treatment and followup were combined with our 9 patients for analysis, making a total of 82 patients in this article. The mean period of patient followup was 84.5 months. There were 26 (31.7%) men and 56 (68.3%) women. The rate of lymph node metastasis was 49%, and distant metastasis was 57.5%. Disease-specific death rate was 37.8%. The 5- and 10-year survival rates of insular carcinoma were 72.2% and 52%, respectively. Patient age older than 45 years (p=0.0004) and distant metastasis (p<0.0001) were poor prognostic factors. Use of radioiodine therapy (p=0.9789) and radiation therapy (p=0.2172) were not associated with prolonged survival. Patients with insular thyroid carcinoma have unfavorable outcomes. Postoperative radioiodine therapy or radiotherapy seemed not to be strongly associated with prolonged survival.