Table 2. Effect of postoperative radiotherapy in 23 patients with AJCC stage IVB ATC.

Treatment	n	Deaths(n)	Postoperative residual tumor rate (%)a	OS rates (%)			P
				1-year	3-year
S	15	14	13 (86.7)	20.0	10.0		0.050
S + X	8	7	7 (87.5)	62.5	37.5

Abbreviations: AJCC, American Joint Committee on Cancer; ATC, anaplastic thyroid carcinoma; OS, overall survival; S, surgery; X, postoperative radiotherapy.

^a No significant difference in the rates of residual disease before radiotherapy between group S and group S + X (P = 0.956).