Extreme thyroid hormone suppression offered no additional survival benefit for patients with high-risk thyroid cancer, whereas moderate thyroid hormone suppression therapy can benefit most patients, according to research in The Journal of Clinical Endocrinology & Metabolism.
Researchers examined the effect of continuing thyroid hormone suppression therapy beyond 1, 3, and 5 years of follow-up by calculating mean TSH scores during the course of each patient’s remaining follow-up.
Researchers found that aggressive thyroid hormone suppression therapy resulted in no additional overall survival advantage when compared with moderate suppression therapy. The overall survival risk ratios for moderate therapy were 0.13, 0.09, 0.13 and 0.33 for thyroid cancer stages I through IV, whereas risk ratios for disease-free survival with moderate therapy were 0.52, 0.4 and 0.18 for stages I through III.
“Previous analysis noted only [overall survival] benefit with moderate [thyroid hormone suppression therapy], whereas current analysis also demonstrates a [disease-free survival] advantage,” the researchers wrote. “In contrast with our previous report, aggressive suppression conferred no additional survival advantage in the high-risk stages as compared with moderate [thyroid hormone suppression therapy]. Even limiting the analysis to patients with distant metastatic disease, maintaining mean TSH levels in the moderate range rather than aggressive is still associated with the best outcomes.”
Researchers also found improved overall survival in patients with stage III thyroid cancer who received postoperative radioiodine (RR = 0.66; P = .04), and in stage IV patients who received a total (RR = 0.66) or near-total thyroidectomy along with radioiodine (RR = 0.7; combined P = .049).
“In my mind, this study might give doctors pause when prescribing long-term, extreme TSH suppression in thyroid cancer patients,” Haugen said in a press release. “Contrary to our results, there is evidence from previous studies that extreme suppression may help in high-risk patients, but maybe then after a few years, when there is no evidence of disease recurrence, this study suggests that doctors could back off when we wouldn’t have before.” – by Regina Schaffer