ESR1 and cancer: Yet, some studies showed that a stronger expression of HMGCR was associated with a less aggressive tumour profile (low histological grade, a small tumour size, oestrogen receptor (ER) positivity, and low proliferation) (50, 51), and HMGCR-positive cancers had longer recurrence-free survival, which was more pronounced in patients with ER-positive tumours (48, 51).