Anti-tumor antibodies as a marker for early detection of ovarian cancer

A50 Background: A lack of reliable early detection tool for ovarian cancer (OvCa) makes the disease the most fatal gynecologic cancer in women. We showed that anti-tumor antibodies (aTAbs) are prevalent in OvCa patients (Barua et al., 2007a) and are a potential diagnostic marker for early detection of OvCa. Since there is no method to identify patients with early stage disease, it is difficult to validate aTAb as an early marker of OvCa. Laying hen is the only animal model that develops OvCa spontaneously and aTAbs are also prevalent in laying hens with OvCa similar to human. Recently, we have established, for the first time, in vivo visualization and monitoring of ovarian tumors in hens using ultrasound imaging with similar probe as in human. In our method, a hen can be screened repeatedly without affecting its physiology. The aim of the present study was to determine if aTAbs appear before the clinical presentation of OvCa and to monitor aTAb positive hens in vivo by transvaginal ultrasound (TUS) for ovarian changes leading to OvCa.
 > Methods: Laying hens of 2.5 - 3years old (n = 40, the incidence rate of OvCa is about 15-20% in this age group) were TUS scanned as reported previously (Barua et al., 2007b), their sera were collected and examined for aTAbs by immunoassay (Luborsky et al., 1990; Barua and Yoshimura, 2001). Ultrasonography of hen ovaries was performed using a commercially available instrument equipped with a transvaginal transducer (Z1, Zonare Medical Systems, CA). Blood flow indices (resistive index [RI] and pulsatility index [PI]) in blood vessels with the highest flow velocity were measured. Hens with lower RI or PI values than normal hens were considered to have abnormal ovarian status. Laying hens with functional ovary (egg laying is an indicator of ovarian function), no abnormal ovarian morphology under grey scale and Doppler TUS and positive (6 hens) or negative (3 hens) for aTAbs were selected. Hens were reared under standard animal husbandry practices, monitored prospectively by in vivo TUS scanning at 15wks intervals until morphological or blood flow changes were observed by US for up to 45 weeks. Upon necropsy, ovarian pathologies were recorded and tissues were processed for routine histology.
 > Result: Gross ovarian tumors were observed in some hens, some had only a portion of ovary with solid masses whereas others had no such obvious abnormalities. All tumors and non-tumor abnormalities were confirmed by HE 30% hen developed non-ovarian pathology and none developed OvCa.
 > Conclusion: This is the first report on the longitudinal observation on anti-tumor antibody appearance and the clinical manifestation of ovarian cancer. These results suggest that aTAbs appear before the clinical presentation of ovarian tumor and may be a viable marker for early detection of OvCa. Support: NIH Ro1AI05506, Rice Foundation, Ovarian Cancer Survivor Network.