Effects of thyroid hormone suppression therapy on adverse clinical outcomes in thyroid cancer.
BACKGROUND
Long-term thyroid hormone (TH) therapy aiming at the suppression of serum thyrotropin (TSH) has been traditionally used in the management of well differentiated thyroid cancer (ThyrCa). However, formal validation of the effects of thyroid hormone suppression therapy (THST) through randomized controlled trials is lacking. Additionally, the role - if any - of TSH effect at low ambient concentrations upon human thyroid tumorigenesis remains unclear.


OBJECTIVE
Evaluation of the effect of THST on the clinical outcomes of papillary and/or follicular ThyrCa.


METHODS
By using a quantitative research synthesis approach in a cumulative ThyrCa cohort, we evaluated the effect of THST on the likelihood of major adverse clinical events (disease progression/recurrence and death). A total of 28 clinical trials published during the period 1934-2001 were identified; only 10 were amenable to meta-analysis. Causality was assessed by Hill criteria.


RESULTS
Out of 4, 174 patients with ThyrCa, 2, 880 (69%) were reported as being on THST. Meta-analysis showed that the group of patients who received THST had a decreased risk of major adverse clinical events (RR = 0.73; Cl = 0.60-0.88; P < 0.05). Further, by applying a Likert scale, 15/17 interpretable studies showed either a 'likely' or 'questionable' beneficial effect of THST. Assessment of causality between TSHT and reduction of major adverse clinical events suggested a probable association.


CONCLUSIONS
THST appears justified in ThyrCa patients following initial therapy. As most primary studies were imperfect, future research will better define the effect of THST upon ThyrCa clinical outcomes.
McGriff
Nayahmka J
NJ
Department of Pharmacy, Warren G. Magnuson Clinical Center, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health (NIH), Building 10, Room 8D12C, 10 Center Drive, MSC 1758 Bethesda, MD 20892-1758, USA.
Csako
Gyorgy
G
Gourgiotis
Loukas
L
Lori C
Guthrie
G
Pucino
Frank
F
Sarlis
Nicholas J
NJ
D002291:Carcinoma, Papillary / Q000628:therapy*; D018265:Carcinoma, Papillary, Follicular / Q000628:therapy*; D006801:Humans; D013963:Thyroid Hormones; D013964:Thyroid Neoplasms / Q000188:drug therapy* / Q000401:mortality; D013972:Thyrotropin / Q000097:blood*; D016896:Treatment Outcome
D013963:Thyroid Hormones; D013972:Thyrotropin