Recently, a new data analysis of 885 breast cancer samples provided by The Cancer Genome Atlas (TCGA) revealed that the number of circRNAs had a relation to breast cancer subtypes, which in estrogen receptor positive (ER+) subtype of normal adjacent tissues was higher than tumor tissues using CircRNA-Seq, and was connected with gene proliferation markers [64]. The gene discussed is ESR1; the disease is breast carcinoma.