Epidemiology, treatment outcome, and survival of anaplastic thyroid cancer (ATC) in the United States: A period prevalence SEER database study 1973-2006.

5588 Background: ATC is a rare, undifferentiated solid tumor with dismal outcome. Contemporary systemic analyses of the epidemiology, outcome and survival of ATC are lacking. We examined the natural history ATC in the US in patients (pts.) diagnosed between 1973-2006. Methods: Using the SEER database including patients diagnosed with ATC between 1973-2006 we performedfrequency analysis on pt. demographics and treatment comparing Caucasian (USW), Hispanic, African-American (AA), and Asian Americans. Multivariate analyses and survival sessions (Kaplan-Meier, age-adjusted) were undertaken. Results: Atotal of 1,776 cases of ATC were reported in the database. ATC comprises 2.2% of all thyroid cancers; is more common in females (65% vs. 35%, p <0.001); with an incidence rate of 3 cases per million. Mean age at diagnosis is 62 yrs. but women were younger at diagnosis (60 vs. 67 yrs, p < 0.001). In 76% cases, the disease was present outside thyroid/neck at diagnosis. Only 24% of the cases were diagnosed with ATC confined to thyroid/neck area. Among male USW, 39% were diagnosed at age less than 50. This is a distinctive trend and unique to ATC among thyroid neoplasms. Comparable 1-year survival (28%) in different groups was observed. But 2-5-year survival was significantly higher in Asian (24%-17%) and Hispanics (24%-18%) than USW (19%-13%) and AA (19%-11%) (p=0.02-0.05). Survival improved considerably over time but more in Asians than others. Cox regression analysis showed that age at diagnosis, extent of ATC, marital status, and year of diagnosis were predictors of death. Relative risk (RR) of death increased when ATC extended outside thyroid/neck at diagnosis and older ages. Persons, who did not receive surgery, had significantly worse survival and higher RR. Conclusions: ATC is rare but more common in women; 76% cases had disease outside thyroid/neck at diagnosis. More USW male were diagnosed at age younger than 50, suggesting that the natural history of this disease is slowly changing. Survival improved considerably over time but remains poor. More studies are warranted to examine these epidemiological and survival trends. No significant financial relationships to disclose.