ABSTRACT
<p><b>BACKGROUND</b>Phenotypic and genotypic heterogeneity is a known feature of many cancers. Whether serum tumor marker kinds vary and change following chemotherapy is still unclear. The aim of this study was to investigate whether there is a change in the expression of serum tumor markers following chemotherapy, and the potential clinical significance in patients with epithelial ovarian carcinoma (EOC) or primary serous peritoneal carcinoma (PSPC).</p><p><b>METHODS</b>Samples were collected before surgery, during chemotherapy and during follow-up for enzyme-linked immunosorbent assay (ELISA)-based evaluation of serum CA-125, CA19-9 and CP2 levels in patients with EOC or PSPC who had received primary debulking surgery followed by adjuvant chemotherapy. In total, 72 patients were examined, including 37 patients with recurrent lesions and 35 patients receiving first-line chemotherapy.</p><p><b>RESULTS</b>In 35 de novo patients, 20% (7/35) demonstrated a significant changed serum tumor marker kinds among whom the patients with mucinous carcinoma (57.1%, 4/7) showed resistance to chemotherapy. In the 37 recurrent patients, 51.4% (19/37) had changed serum tumor markers, of whom 57.9% (11/19) presented with serous carcinoma. There was no significant difference in median progression-free survival or overall survival in patients with drug-sensitive or drug-resistant recurrence in patients with changed tumor marker kinds relative to those with unchanged markers. However, for patients with changed serum tumor markers there was a trend towards prolonged survival compared with the unchanged serum tumor marker group. In the 17 patients with secondary recurrence, 37.5% (6/17) had changed tumor marker levels. The ratios of CA-125/CP2 and CA-125/CA19-9 were significantly different after either chemotherapy or recurrence.</p><p><b>CONCLUSIONS</b>Serum tumor marker expression in patients with EOC or PSPC may change after chemotherapy or recurrence, indicating that in addition to the markers that are abnormal before surgery, those markers that are normal should also be monitored during chemotherapy and follow-up.</p>
