This agent is a selective estrogen receptor modulator (SERM) that increases both estradiol and progesterone levels [20] and it is also able to increase cell proliferation; thus, an association between the use of CC and the risk of cancer has been hypothesized for gynecologic tumors, such as breast, ovarian cancer and endometrial cancer [3-6]. This evidence concerns the gene ESR1 and female reproductive system neoplasm.