**3. HE4 as a biomarker in ovarian cancer**

HE4 is a complementary biomarker to CA125 (Carbohydrates Antigen125). HE4 has potential to complement or even is a better alternative to carbohydrate antigen 125 (CA125) [10–12]. Currently CA125 is being used as a biomarker for the diagnosis and therapeutic monitoring in ovarian cancer. CA125 is raised in only 50% of stage I epithelial ovarian cancers, and only about 80% in all epithelial ovarian cancers [13]. So for all practical purposes, CA125 cannot be used as an independent biomarkerfor the diagnosis of EOC, while HE4 can be used as a stand-alone biomarker, in both diagnosis and prognosis of EOC and endometrial cancers [14, 15]. It has also been approved by the United States of America (USA), Food and Drug Administration (FDA) as a biomarker to monitor patients with epithelial ovarian cancer [16].

Studies show that serum level of HE4 and CA125 together can be used as an indicator of prognosis in ovarian cancer. The two together has shown positive results, sensitivity of 76.4% and specificity of 95% [17]. Individually, HE4 is a well known biomarker for the diagnosis and therapeutic monitoring for ovarian cancer.
