Clinical significance of serum vascular endothelial growth factor in colorectal cancer patients: correlation with clinicopathological factors and tumor markers

Impact of vascular endothelial growth factor-A expression, thrombospondin-2 expression, and microvessel density on the treatment effect of bevacizumab in metastatic colorectal cancer

PURPOSE

Bevacizumab is a monoclonal antibody to vascular endothelial growth factor-A (VEGF). In the pivotal trial in metastatic colorectal cancer (mCRC), addition of bevacizumab to first-line irinotecan, fluorouracil, and leucovorin (IFL) significantly prolonged median survival. The aim of these retrospective subset analyses was to evaluate VEGF, thrombospondin-2 (THBS-2), and microvessel density (MVD) as prognostic factors and/or predictors of benefit from bevacizumab.

PATIENTS AND METHODS

In the pivotal trial, 813 patients with untreated mCRC were randomly assigned to receive IFL plus bevacizumab or placebo. Of 312 tissue samples collected (285 primaries, 27 metastases), outcome data were available for 278 (153 bevacizumab, 125 placebo). Epithelial and stromal VEGF expression were assessed by in situ hybridization (ISH) and immunohistochemistry on tissue microarrays and whole sections. Stromal THBS-2 expression was examined by ISH on tissue microarrays. MVD was quantified by Chalkley count. Overall survival was associated with these variables in retrospective subset analyses.

RESULTS

In all subgroups, estimated hazard ratios (HRs) for risk of death were < 1 for bevacizumab-treated patients regardless of the level of VEGF or THBS-2 expression or MVD. Patients with a high THBS-2 score showed a nonsignificant improvement in survival following bevacizumab treatment (HR = 0.11; 95% CI, 0.02 to 0.51) compared to patients with a low score (HR = 0.65; 95% CI, 0.41 to 1.02); interaction analysis P = .22. VEGF or THBS-2 expression and MVD were not significant prognostic factors.

CONCLUSION

These exploratory analyses suggest that in patients with mCRC addition of bevacizumab to IFL improves survival regardless of the level of VEGF or THBS-2 expression, or MVD.

Clinical significance of detection for vascular endothelial growth factor in resection margin following total mesorectal excision

AIM: To investigate the expression and its significance of vascular endothelial growth factor (VEGF) in the resection margin following total mesorectal excision (TME) for human rectal cancer.

METHODS: VEGF was detected in the tissue specimens of cancer, distal mesorectal margin (DMM), circumferential resection margin (CRM) and outer pelvic fascia from 60 rectal cancer patients received TME. The pathological data were retrospectively analyzed.

RESULTS: VEGF expression was significantly higher in the tissues of rectal cancer than that in the normal tissues (54/60 vs2/20, P < 0.001). VEGF was also expressed in tissues of CRM (9/60). However, no VEGF expression was detected in the tissues of DMM and outer pelvic fascia. VEGF expression was closely related with the differentiation degree, Dukes staging and lymph node metastasis (P < 0.05 or P < 0.01).

CONCLUSION: VEGF is highly expressed in tissues of rectal cancer, and negatively or weakly positively expressed in DMM and CRM.

Clinical implications of circulating angiogenic factors in cancer patients

PURPOSE

Angiogenesis, a process fundamental to tumor growth, is regulated by angiogenic factors. This article reviews prognostic and other clinical implications of circulating angiogenic factors in cancer patients.

METHODS

A MEDLINE search of literature was performed using the names of various angiogenic factors as the key words. Studies pertaining to circulating angiogenic factors in cancer patients were reviewed. Pertinent literature regarding tumor expression of common angiogenic factors and their prognostic relevance in human cancers were also examined.

RESULTS

A substantial number of studies have demonstrated a strong association between elevated tumor expression of vascular endothelial growth factor (VEGF) and advanced disease or poor prognosis in various cancers. This supports the pivotal role of VEGF in regulating tumor angiogenesis. More recently, there is mounting evidence that the level of circulating VEGF in patients with different types of cancer may be predictive of tumor status and prognosis. Preliminary data also suggest that circulating VEGF may be useful in predicting and monitoring tumor response to anticancer therapies and in follow-up surveillance for tumor relapse. There are reports supporting the prognostic value of other circulating angiogenic factors such as basic fibroblast growth factor, platelet-derived endothelial cell growth factor, transforming growth factor-beta, and angiogenin, but their clinical significance is less conclusive because of limited data.

CONCLUSION

Circulating VEGF seems to be a reliable surrogate marker of angiogenic activity and tumor progression in cancer patients. Evaluation of circulating angiogenic factors is a promising novel approach of prognostication in cancer patients that has the advantages of being convenient and noninvasive, and it may provide new prognostic information that is not afforded by conventional clinicopathologic prognostic indicators.