Statistical analysis

Quantitative data were reported as mean, median, standard deviation and interquartile range. The qualitative variables were expressed as absolute frequencies and percentages. Chi-square test (or F-Fisher Exact test when appropriate) and Proportion Test were used to assess association between categorical variables:

Correlation between menopausal status and thyroid disease, autoimmune thyroid disease or thyroid function;

Correlation between breast cancer biological profile and thyroid disease, autoimmune thyroid disease or thyroid function;

Correlation between breast cancer staging and thyroid disease, autoimmune thyroid disease or thyroid function;

Correlation between breast cancer grading and thyroid disease, autoimmune thyroid disease or thyroid function.

Statistical analysis was performed using R (the R Foundation for Statistical Computing; Version 3.0.3) software. A p value less than 0.05 was considered statistically significant.