Hashimoto's hypothyroidism is associated with a 44% increase in Heart disease in women under the age o 49. A non-significant change was seen in men. This study found that T4 therapy reduced this risk. A better study would have been if T4 was compared to T4 + T3.
This one size treats all approach that medicine takes in its recommendations to cancer evaluation is BS (forgive my french). Women with Hashimoto's disease are at increased risk of Papillary Thyroid cancer risk (30%) compared to those without.