Thyroid cancer: cell of origin sets the marker
Four thyroid cancers, and the cell of origin predicts everything. Papillary and follicular come from follicular cells — both track with thyroglobulin; papillary is common and indolent, follicular spreads through blood. Medullary is the outlier: C cells, secreting calcitonin, driven by RET (think MEN2, familial). Anaplastic is de-differentiated and lethal.
