Lower levels of TSH are associated with a lower risk of papillary thyroid cancer in patients with thyroid nodular disease: thyroid autonomy may play a protective role

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   Figure 1

   Prevalence of PTC according to serum TSH concentrations. Patients with serum TSH level within the normal range were divided into four quartiles of similar size according to their TSH values. Patients with serum TSH levels lower (0.4 μU/ml) or higher (from 3.5 to 10 μU/ml) than the normal range values were considered separately. The odd ratio and 95% confidence interval of PTC according to TSH levels are reported in Table 3.
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   Figure 2

   Box-whisker plots illustrating median, quartiles, and ranges of TSH levels according to age. As shown in panel A, serum TSH levels show a significant reduction with age (Kruskall–Wallis test, P<0.0001). The number of patients included in each age group is indicated in the bottom of the figure. When BTND (white box) and PTC (gray box) patients were grouped according to age (B), TSH was significantly higher in PTC than in BTND in all age groups (*=χ², P<0.01). Besides, BTND patients showed a significant, age-dependent reduction of TSH values (Kruskall–Wallis test, P<0.0001), while in PTC the reduction of TSH in older patients was less evident and only slightly significant (Kruskall–Wallis test, P=0.03). The number of patients with BTND and PTC in each age group is indicated in the bottom of the figure.
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   Figure 3

   Frequency of thyroid autonomy in PTC (gray bars) and BTND (white bars) according to age in patients with thyroid autonomy. In BTND patients, a progressive, age-dependent increase of thyroid autonomy was observed, while no age-dependent distribution was present in PTC patients. With the exception of younger subjects, the frequency of thyroid autonomy was significantly higher in BTND than PTC in all classes of age (*=χ², P<0.01). Similar results were observed both in the whole cytological series (panel A) and in the subgroup of patients submitted to surgery (panel B). The number of patients with thyroid autonomy (BTND+PTC) in each age group is reported in the bottom of the figure. The total number of patients in each age group is indicated in Fig. 2.
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   Figure 4

   Panel A, frequency of PTC in the whole groups of patients with MNG and S/I (black bars) and in the same patients subdivided according to the presence (gray bars) or the absence (white bars) of thyroid autonomy. Panel B, frequency of thyroid autonomy according to clinical diagnosis (MNG and S/I) in patients with BTND (white bars) and those with PTC (gray bars). The statistical differences between the groups (χ² and P values) are reported.
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   Figure 5

   Box-whisker plot illustrating median, quartiles, and ranges of TSH levels in PTC according to TNM. Panel A: TSH levels in patients with stage T3–T4 (striped box) were significantly higher (Mann–Whitney test P<0.001) than in stage T1–T2 (white box). Panel B: TSH values in patients with N1 (dotted columns) were significantly higher (Mann–Whitney P=0.002) than in patients with N0 (gray columns).
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   Figure 6

   Box-whisker plot illustrating median, quartiles, and ranges of TSH levels according to the presence of anti-thyroid antibodies (TAb). TSH levels in PTC (gray box) were significantly higher than in BTND (white box) both in TAb positive patients and in subjects with no detectable TAb (Mann–Whitney test, P<0.01).

• © 2009 Society for Endocrinology