Human Epididymis Protein 4

Serum

0.8 mL

0.4 mL (Note: This volume does not allow for repeat testing.)

Red-top tube or gel-barrier tube

No special patient preparations are required.

The assay is used as an aid in monitoring recurrence or progressive disease in patients with epithelial ovarian cancer. Serial testing for patient HE4 assay values should be used in conjunction with other clinical findings used for monitoring ovarian cancer.

The HE4 assay should not be used as a cancer screening test.

HE4 levels tend to be higher in older women and in women who began menstruating at an older age, but these affects are small.¹ Falsely elevated or depressed values of HE4 may occur in samples containing human antimouse antibodies.² Levels of HE4 within the reference range do not preclude the presence of cancer, nor are elevated results an absolute indication of malignancy; thus, HE4 should not be used for cancer screening.² HE4 should not be used for monitoring patients with mucinous or germ cell ovarian cancer. Results should be interpreted in conjunction with other clinical and laboratory findings.²

The measured HE4 value of a patient's sample can vary depending on the testing procedure used. The laboratory finding must therefore always contain a statement on the HE4 assay method used. HE4 values determined on patient samples by different testing procedures cannot be directly compared with one another and could be the cause of erroneous medical interpretations. If there is a change in the HE4 assay procedure used while monitoring therapy, then the HE4 values obtained upon changing over to the new procedure must be confirmed by parallel measurements with both methods.

There is no high dose hook effect at HE4 concentrations up to 40000 pmol/L.

Patients with confirmed ovarian cancer may have HE4 assay values in the same range as healthy women. Certain histological types of ovarian cancer (e.g. mucinous or germ cell tumors) rarely express HE4, therefore the use of the Elecsys HE4 assay is not recommended for monitoring of patients with known mucinous or germ cell ovarian cancer.³ Conversely, elevated levels of HE4 antigen may be present in individuals with renal, liver and non-malignant diseases.

Electrochemiluminescence Immunoassay (ECLIA)

The distribution of HE4 levels determined in 1147 specimens is shown in the table.

Monitoring of disease status in patients diagnosed with ovarian cancer.

The effectiveness of the HE4 EIA as an aid in monitoring of disease status in ovarian cancer patients was determined by assessing changes in HE4 levels in serial serum samples from 80 patients compared to changes in disease status. A study involving a total of 354 pairs of observations was undertaken with an average number of 4.4 observations per patient. A positive change in HE4 was defined as an increase in the value that was at least 25% greater than the previous value of the test. This level of change takes into account the variability of the assay and the biological variability. Sixty percent or 76/126 of the patient samples with a positive change correlated with the disease progression, while 75% or 171/228 of the patient serial samples with no significant change in HE4 value correlated with no progression. The total concordance was 70% or 247/354. The following table presents the data in a 2 x 2 format.

The following table shows the resulting sensitivities and specificities of the HE4 EIA compared to the disease status at various changes in HE4 EIA concentrations.

• Sensitivity is represented as a concordance of the HE4 EIA to progression of disease.

• Specificity is represented as a concordance of the HE4 EIA to no progression of disease.

Human epididymis protein 4 (HE4) was first identified in the epithelium of the distal epididymis and was originally predicted to be a protease inhibitor involved in sperm maturation.^4,5 HE4 is the gene product of the WFDC2 gene that is located on chromosome 20q12-13.1. The WFDC2 gene is one of 14 homologous genes on this chromosome that encode proteins with WAP-type four disulphide core WFDC2) domains.^6,7 HE4 belongs to the family of whey acidic four-disulfide core (WFDC2) proteins with suspected trypsin inhibitor properties.⁸ However, no biological function has so far been identified for HE4.⁸ The HE4 gene codes for a 13-kD protein, although in its mature glycosylated form the protein is approximately 20−25 kD, and consists of a single peptide and two WFDC domains.⁹

HE4 has been reported to be expressed in a number of normal tissues, including epithelia of respiratory and reproductive tissues.^9,10 Elevated levels were found in several tumor cell lines, including ovarian, lung, colon, and breast cancer. A number of independent microarray studies have shown that the WFDC2 gene is overexpressed in patients with ovarian carcinoma relative to normal controls.^10-14 In 2003, Hellstrom and coworkers showed that secreted HE4 was detected in high levels in the serum of ovarian cancer patients.¹⁵ This group found that measurement of HE4 showed sensitivity and specificity comparable to that of CA125 for differentiating postmenopausal women with ovarian cancer from normal controls.¹⁵ They suggested that the HE4 assay might be superior to CA125 in that it is less frequently positive in patients with nonmalignant disease.¹⁵

Drapkin and coworkers used immunohistochemical techniques to show that cortical inclusion cysts lined by metaplastic Müllerian epithelium abundantly expresses HE4 relative to normal surface epithelium.¹⁶ Using tissue microarrays, they showed that HE4 expression was restricted to certain histologic subtypes of epithelial ovarian carcinomas (EOC).¹⁶ HE4 was expressed in 93% of serous and 100% of endometrioid EOC expressed HE4, whereas only 50% and 0% of clear cell carcinomas and mucinous tumors, respectively, were found positive.¹⁶ This study also revealed that most nonovarian carcinomas do not express HE4, consistent with previous findings that HE4 protein expression is highly restricted in normal tissue of the reproductive tracts and respiratory epithelium.¹⁶

Moore and coworkers showed that HE4 had a slightly better sensitivity for detecting EOC than CA125.^17,18 These researchers found that HE4 was particularly superior for detecting stage I disease, with no increase in sensitivity when combined with CA125 or any other marker.^17,18 Overall they found that combining CA125 and HE4 provided a more accurate predictor of malignancy than either alone.¹⁹ Montagnana and coworkers found that receiver operating characteristics curve analysis on healthy controls and patients with ovarian cancers revealed that HE4 had a significantly higher area under the curve than CA125 (0.99 vs 0.91), with a sensitivity and specificity of 98% and 100%, respectively.²⁰ Mean HE4 levels were found to be significantly higher in patients with endometrial or ovarian cancer than in patients with ovarian endometriomas or other types of endometriosis.^20,21 These findings suggest that the HE4 test may be valuable in discriminating ovarian tumors from ovarian endometriotic cysts.^20,21

Shaw and coworkers showed that the ability of serum HE4 levels to discriminate ovarian cancer cases from healthy and benign controls is not influenced by risk status.²² Several other studies have indicated that including HE4 in a multivariate analysis of ovarian cancer risk served to improve the accuracy of screening and/or disease monitoring.^3,23-25