Regional Variation across Canadian Centers in Radioiodine Administration for Thyroid Remnant Ablation in Well-Differentiated Thyroid Cancer Diagnosed in 2000–2010

Table 5

(a) Center specific guidance for initial thyroid remnant ablation in Canada (2000–2010). (b) Radioactive iodine preparation protocols, specified per center.

(a)

Center	Guidelines	Risk category	Dose (GBq)	Population	Protocol changes 2000–2010
London,ON	ATA	Intrathyroidal disease (T1–T3, multifocal)	3.7	ATA guidelines	Prior to 2009: all papillary >1 cm, multifocal micropapillary with aggregated diameter ≥1 cm, all follicular, all N1 and M1
					2009-2010; no therapy for T1 except of aggressive variants RAI doses have not changed
		N1, ETE	5.5
		M1	7.4
Halifax, NS	Local guidelines adapted from ATA	Very low risk	1.1	Pts with nodal disease; P T3 and P T4; Other risk factors: lymphovascular invasion, perineural invasion, aggressive variants	Prior to 2009: RAI considered for all pts except pT1 N0, young (<45) F.
		Low risk	3.7
		Intermediate risk with significant nodal disease	5.5		After 2009: more selective approach of pts selection for RAI administration; RAI doses have not changed
		High risk, distant mets, gross residual disease	7.4
Winnipeg, MB	Local (CancerCare Manitoba)	Low risk	1.1	TNM (originally)	Established in 2001
		Intermediate risk	3.7	Now individualized	No changes until 2014
		High risk	5.5
		M1	7.4
Toronto, ON	ATA and local	Low risk	<1.1	ATA guidelines	After 2005: no treatment for low risk and some moderate risk lower doses 1.1–2.8 instead of 3.7–5.5
		Moderate risk	1.1–2.8
		High risk	>2.8
St. John’s, NL	ATA	Not provided	N/A	Almost all patients are treated	No changes
Hamilton, ON	Local	Not provided		All follicular carcinomas Papillary with nodal involvement T4 stage	Doses have been decreased gradually
Fredericton, NB	Toronto, ON protocol	Not provided		All patients except those who decline or have microcarcinomas	Prior to 2012: All pts went to Radiation Oncology and Whole Body Scan-based follow-up; Stim Tg and US not done routinely

(b)

Centers	Low iodine diet (days)	rhTSH (thyrogen)	L-T4 withdrawal	L-T4 withdrawal time (weeks)	Liothyronine	Liothyronine protocol
London, ON	12 (10 before RAI and 2 after)	Occasional cases before 2000	Used rarely (if pt unable to get rhTSH or if patient already hypothyroid on the first visit)	4	Never	N/A
		Almost everybody since 2000		If TSH is <30, wait extra week
Halifax, NS	14	Occasional cases from 2005, more routine from 2008	Used rarely (if pt unable to get rhTSH or if patient already hypothyroid on the first visit)	4	Yes	25 mcg po BID for two weeks, start on the day of T4 withdrawal 2 weeks off
Winnipeg, MB	9 (7 before and 2 after RAI)	Rarely	Always TSH > 30 mL/L	3	Prior to 2009	4 weeks 25 mcg TID, 2 weeks off
St. John’s, NL	14	Occasional cases before 2004, after used routinely	Used infrequently, over time all pts switched to rhTSH	6	Yes	2-3 weeks on 2-3 weeks off (dose not specified)
Toronto, ON	14	Since 2008	No (except in pt with metastatic/advanced disease)	3	No	N/A
Hamilton, ON	14	Since 2009	Yes; TSH was not tested	4	Yes	2 weeks on 25 mcg-bid,; 2 weeks off
Fredericton, NB	14	Since 2012/2013	Rarely used (only if patient is unable to access rhTSH TSH goal >35 mL/L)	2–5	No	N/A