Stromal ERα was progressively upregulated during cervical carcinogenesis, with an immunoreactive score (IRS) of 1.3 ± 1.5, 2.1 ± 1.9, and 3.6 ± 3.3 in the CIN2/3, CIS, and ICC groups, respectively (p < 0.001). Here, ESR1 is linked to in situ carcinoma.