TSH, Thyroid Hormone, and PTC—Letter

Abstract

Huang and colleagues (1) reported on the relationship between papillary thyroid cancer risk and prediagnostic levels of thyroidstimulating hormone (TSH) and lent support to our previous findings (2) on the existence of an inverse association. The two studies were case-control studies nested in very different populations, that is, U.S. military staff mainly below age 50 years (400 male and 341 female cases; ref. 1) and healthy volunteers from the European Prospective Investigation in Cancer and Nutrition cohort (300 and 57, respectively, median age 51; ref. 2). The strength of the inverse association among the vast majority of women and men who had TSH levels within the reference limits was similar, that is, ORs of approximately 0.60 in the highest versus the lowest tertile in Huang and colleagues (1) or genderspecific quartile in our study (2). However, gender-specific analyses of individuals with TSH levels outside the reference limits led Huang and colleagues (1) to a different conclusion, that is, that increased thyroid cancer risk was associated with TSH below the reference limits among women but above the reference limits among men (1). We caution against overinterpreting differences

GWAS of thyroid stimulating hormone highlights pleiotropic effects and inverse association with thyroid cancer

“…Previous studies have led to inconsistent conclusions on the relationship between TSH levels and thyroid cancer risk 8 . Several studies have observed an association between low TSH levels, which can occasionally occur as a consequence of autonomous thyroid nodules and an increased risk of thyroid cancer [8][9][10][11][12][13] . In contrast, several studies have indicated that TSH promotes the growth of thyroid cancers 8, [14][15][16] , which has led to the recommendation to lower TSH levels among people with thyroid cancer to reduce the risk of cancer recurrence.…”