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BACKGROUND: The importance of stroma for tumor progression is recognized for many cancer types. In this study, we aim to evaluate the expression of types I (Col1) and IV (Col4) collagens, alpha-smooth muscle actin (a-SMA), and matrix metallopeptidase 9 (MMP-9) in the tumor stroma of small papillary thyroid carcinoma (PTC).

MATERIAL AND METHODS: Twenty-five non-metastatic small PTCs (pT1N0) and nineteen metastatic small PTCs (pT1N1b) including corresponding metastatic lateral lymph nodes were selected and paraffinized tissue blocks retrieved. The samples were stained for Col1, COL4, a-SMA, and MMP-9 antibodies using immunohistochemistry. The expression of the stromal proteins was scored and analyzed based on the location, intensity, and distribution.

RESULTS: Col1 and Col4 expression were significantly higher in normal thyroid tissue compared to PTC tissue. On the contrary, expression of a-SMA and MMP-9 was higher in PTC tissue compared to normal thyroid tissue. Both Col1 and Col4 were significantly more highly expressed in the non-metastatic tumors compared with metastatic tumors. The expression of a-SMA and MMP9 was slightly, but not significantly, higher in the metastasized tumors and their respective lymph nodes. There was a significant correlation between the metastasized tumors and their respective lymph nodes in Col1 and MMP-9 expression.

CONCLUSIONS: Col1, Col4, a-SMA, and MMP-9 expression in PTCs differs significantly from that of normal thyroid tissue. The higher expression of Col1 and Col4 in normal thyroid tissue and in the non-metastasized tumors indicates that Col1 and 4 might have a potential protective role in tumor progression. The higher expression of a-SMA and MMP9 in PTCs indicates that these proteins might have a role in promoting PTC progression and aggressiveness.

Background: The western world is seeing a rising incidence of thyroid cancer. Improved diagnostic methods do not entirely explain this increase. Papillary thyroid carcinoma (PTC) is the most common subtype of thyroid cancer. Small PTC (<= 20 mm) and especially papillary thyroid microcarcinomas (PTMC <= 10 mm) are considered to be low-risk tumors but some cases are considerably more aggressive. Sufficient understanding of these mechanisms is a long-term goal for more efficient and safer treatment of these tumors.

Methods: We identified 959 cases of small PTCs in the validated Scandinavian Quality Register for Thyroid, Parathyroid and Adrenal Surgery, grouped according to lymph node metastasis. These were analyzed according to age, gender, tumor size and geographic region.

Results: Patients with N1b disease (lateral lymph nodes metastases) had a smaller tumor size compared to patients with N1a disease (8.6 mm vs 10.1 mm respectively, p < 0.05). Patients and specifically females with N1b disease were younger than those with N0 or N1a disease. Patients with N1b disease had a lower proportion of females (60%) compared to N0 and N1a groups (81% and 78%, respectively). The incidence of operated small PTCs and of lymph node engagement differs between geographic regions in Sweden.

Conclusions: Small PTC and especially PTMC seem to show different patterns of aggressiveness and demography regarding lateral lymph node metastases and 7% had N1b disease and tumor <1 cm, underscoring the importance of lymph node evaluation in PTMC patients. More understanding of predictive factors, mechanisms for metastatic disease and causes of regional differences, is needed.

AIMS: To study the correlation between clinicopathological risk factors and the risk for intervention-requiring cancer recurrence in patients with small papillary thyroid cancers (sPTCs). MATERIALS AND METHODS: Records for 397 patients with sPTC (T1 ≤ 20mm) were obtained from the Scandinavian Quality Register for Thyroid, Parathyroid and Adrenal Surgery (SQRTPA) between 2010 and 2016. Follow-up time was at least 5 years. Data regarding intervention-requiring cancer recurrence were obtained from patient medical records and analysed regarding lymph node (LN) status (N0, N1a and N1b) and recurrence. RESULTS: Age was significantly lower in the N1a and N1b groups compared to N0 (45 vs. 40.5 vs. 49 years, respectively; p = 0.002). Tumour size was smaller in the N1a group compared to N1b group (9 vs. 11.8 mm; p <0.01). The mean number of metastatic LNs at initial surgery was higher in the N1b compared to N1a group (6.6 vs. 3; p = 0.001), and in the recurrent compared to the non-recurrent group (7 versus 3.9; p <0.01). The recurrence rate was higher in the N1b group than the N1a and N0 groups (25% vs. 2.4% vs. 1.4%, respectively; p = 0.001). CONCLUSIONS: Lymph node stage N1b at diagnosis, and having five or more metastatic nodes, are strong risk factors for cancer recurrence and decreased disease-free survival in sPTC. The management of patients with sPTC should include thorough lymph node mapping for optimal treatment and individual risk stratification.

A steep increase of small papillary thyroid cancers (sPTCs) has been observed globally. A major risk factor for developing PTC is ionizing radiation. The aim of this study is to investigate the spatial distribution of sPTC in Sweden and the extent to which prevalence is correlated to gamma radiation levels (Caesium-137 (Cs-137), Thorium-232 (Th-232), Uranium-238 (U-238) and Potassium-40 (K-40)) using multiple geospatial and geostatistical methods. The prevalence of metastatic sPTC was associated with significantly higher levels of Gamma radiation from Th-232, U-238 and K-40. The association is, however, inconsistent and the prevalence is higher in densely populated areas. The results clearly indicate that sPTC has causative factors that are neither evenly distributed among the population, nor geographically, calling for further studies with bigger cohorts. Environmental factors are believed to play a major role in the pathogenesis of the disease.