Suppressing thyroid-stimulating hormone after thyroid cancer resection increases the risk for osteoporosis without decreasing recurrence, according to data presented at the American Thyroid Association meeting.

 “TSH suppression up to 0.4 mU/L increases the risk of osteoporosis without changing recurrence in thyroid cancer patients at low and intermediate risk of recurrence,” said Laura Y. Wang, MD, of the department of surgery at Memorial Sloan-Kettering. “Thus, future therapeutic efforts should focus on avoiding harm in indolent disease.”

Wang presented a retrospective study looking at patients who had a total thyroidectomy at Memorial Sloan-Kettering Cancer Center from 2000 to 2006 with a median follow-up of 6.5 years. The study criteria excluded patients with primary hyperparathyroidism, fewer than three postoperative TSH lab results, preoperative atrial fibrillation, preoperative osteoporosis, and considered high risk by the ATA; they also excluded men from the osteoporosis analysis. After these exclusions, the study looked at 771 total patients and 537 patients in the osteoporosis analysis.

Patients with median TSH ≤0.4 mU/L were considered TSH suppressed. TSH labs were analyzed up to original recurrence or last follow-up.

“TSH suppression was the most powerful independent predictor of osteoporosis, conferring a nearly fourfold risk of development of postoperative osteoporosis,” Wang said. “The impact on TSH on osteoporosis risk was even higher on univariate analysis, increasing the HR from almost 3.5 to 4.3. This suggests that there is possibly a synergistic effect between older age and TSH suppression.”

The disease-free survival analysis showed that 43 of 771 (5.6%) patients recurred (HR=1.02; 95% CI, 0.54-1.91). After multivariate adjustment for age, gender, ATA risk of recurrence and administration of radioactive iodine, TSH suppression did not prevent recurrence (HR=0.88; 95% CI, 0.46-1.66).

The survival estimate for osteoporosis in this group showed 29 of the 537 (5.4%) developed postoperative osteoporosis (HR=3.5, 95% CI, 1.2-10.2). After multivariate analysis, the HR increased to 4.32 (95% CI, 1.45-12.85).

“It appears that at a TSH level of around 0.9-1 [mU/L], the risk of osteoporosis disappears but the risk of tumor recurrence remains unchanged,” Wang said.

Soure: Endocrine Today