Prognostic factors and treatment outcomes for anaplastic thyroid carcinoma: ATC Research Consortium of Japan cohort study of 677 patients.

BACKGROUND

Anaplastic thyroid carcinoma (ATC) accounts for only 1 to 2% of all thyroid carcinomas, but it is one of the most lethal neoplasms in humans. To date, most findings about ATC have been derived from single-institution studies with limited numbers of cohorts. To obtain further insights into this "orphan disease," we have established a multicenter registry, the ATC Research Consortium of Japan (ATCCJ). We analyzed prognostic factors and treatment outcomes using the large cohort database of the ATCCJ.

METHODS

Most of the Japanese centers involved in the treatment of thyroid cancer were invited to join the ATCCJ and have provided information on ATC patients treated between 1995 and 2008. The database includes 677 cases from 38 registered institutions. Survival curves were determined using Kaplan-Meier methods and were compared using the log-rank test. Cox's proportional hazards model was used for multivariate analysis.

RESULTS

Clinical varieties of ATC were classified into four types: common type (n = 547); incidental type (n = 29); anaplastic transformation at the neck (n = 95); anaplastic transformation at a distant site (n = 6). The incidental type followed by anaplastic transformation at the neck showed better outcomes than the other types. Anaplastic transformation at a distant site showed the worst outcomes. The 6-month and 1-year cause-specific survival (CSS) rates for common-type ATC were 36 and 18%, respectively. In all, 84 (15%) achieved long-term (>1 year) survival. Multivariate analysis identified age ≥70 years, presence of acute symptoms, leukocytosis (white blood cell count ≥10,000/mm(3)), large tumor >5 cm, T4b tumor, and distant metastasis as significant risk factors for lower survival. CSS rates also differed significantly depending on UICC stages, with 6-month CSSs of 60% for stage IVA, 45% for IVB, and 19% for IVC. For 36 of 69 (52%) stage IVA patients who underwent radical surgery, adjuvant therapies, including radiation therapy (RTX) and chemotherapy (CTX) did not show additional benefit statistically. Conversely, among 242 stage IVB patients, 80 (33%) underwent radical surgery. For those patients, therapies combining RTX with CTX significantly improved CSS.

CONCLUSIONS

Long-term survival is possible for selected patients with ATC. To determine the treatment strategy, UICC stage (disease extent) and other prognostic factors (e.g., biologic malignancy grade) should be considered.