Background: Tumor angiogenesis is essential for solid tumor growth. Yet, the importance of any particular factor in neoplastic proliferation is poorly defined. This study examines the clinical significance of increased expression of one of the angiogenic factors, vascular endothelial growth factor (VEGF), in early stage ovarian carcinoma.
Methods: Tumor specimens from 68 patients with International Federation of Gynecology and Obstetrics Stage I and II ovarian carcinoma were evaluated for VEGF expression. Antisense and corresponding sense (control) RNA probes were transcribed from the pCRII construct (Invitrogen, San Diego, CA), which contained human VEGF cDNA. The antisense probe was designed to include a highly conserved region of the VEGF coding sequence and thus detect all known variants. After in situ hybridization, sections were assessed for overexpression of VEGF.
Results: Twenty-nine of the tumor samples overexpressed VEGF, whereas 39 specimens did not. In patients whose tumors demonstrated elevated VEGF expression, 25% were without evidence of disease recurrence at last follow-up. In contrast, 75% of the patients whose tumors did not overexpress VEGF were without evidence of disease at last follow-up (P < 0.001). Median disease free survival for the VEGF positive group was 22 months, compared with > 108 months for the VEGF negative group (P < 0.001). When borderline tumors were excluded from the survival analysis, median disease free survival for the VEGF positive group was 18 months, compared with >120 months for the VEGF negative group (P < 0.001). Other possible prognostic variables had minimal impact on survival; these included age, stage, grade, cytology, and tumor size (P > 0.05). Assignment to a high risk group, as defined by the Gynecologic Oncology Group of the National Cancer Institute, was somewhat predictive of a shorter relapse free interval (P = 0.056). In a multivariate analysis, however, only elevated VEGF expression was associated with poorer survival.
Conclusions: In this analysis, patients with early stage ovarian carcinoma with increased VEGF expression had a poorer prognosis. Further study of VEGF may ultimately lead to identification of patients with high risk lesions whose tumor biology portends a worse prognosis and who therefore may benefit from aggressive adjuvant therapy.