IGFBP-3 Gene Methylation in Primary Tumor Predicts Recurrence of Stage II Colorectal Cancers

Colorectal cancer (CRC) is the fourth most common cancer in the United States.1 Worldwide, the incidence is increasing, with an annual estimate of 1,233,700 new cases diagnosed and 608,700 deaths.2 The 5-year survival of patients with stage II is approximately 75% to 82%.3,4 There are still about 20% of patients with this stage of tumors who die of recurrent disease. There is clearly a need to identify prognostic factors to guide the identification of stage II patients who are likely to experience recurrence. This information would allow more informed planning for patients who are more likely to require and possibly benefit from intensive surveillance or adjuvant therapy. In current practice, a limited set of clinical and pathologic markers (ie, T4 tumors, poor histologic grade, lymphovascular invasion, perineural invasion, bowel obstruction, lesions with localized perforation or close, indeterminate, or positive margins, less than 12 nodes examined) can identify small groups of patients with stage II disease who have higher recurrence risk. The majority of patients do not have a marker that categorizes them as higher risk. In light of the importance of this issue, there have been many attempts to find novel molecular markers, such as microsatellite instability (MSI)/mismatch repair,5,6 LOH 18q,7 expression/mutation/methylation of individual genes or groups of genes,8–13 to identify patients with the potential for CRC recurrence. However, the clinical utilities of these markers are still under study. Dissemination to locoregional lymph nodes (LNs) is also an important prognostic factor in CRC. Current clinical detection of micrometastases by standard immunohistochemistry techniques is limited to those with a minimal number of cells. Technical advances now permit the detection of micrometastases at the molecular level. For example, somatic gene mutations or methylation and amplification of cancer-specific RNA that occur in the primary tumor (PT) are detectable in LNs.14–19 We have recently correlated DNA methylation of 6 extracellular matrix genes with outcome of patients with CRC. Among all genes analyzed, DNA methylation of the insulin-like growth factor binding protein 3 (IGFBP-3) gene showed the strongest association with poor survival.20 In experimental models, insulin-like growth factor-I (IGF-I) promotes the growth and metastasis of CRC cells,21–24 whereas IGFBP-3 inhibits growth through ligand sequestration and may also have antiproliferative and proapoptotic activities through actions independent of the IGF-I/IGF-I receptor.25 Several clinical studies have shown that circulating IGF-I is elevated and IGFBP-3 levels reduced in patients before the diagnosis of CRC and that increased plasma levels of IGFBP-3 are associated with a decreased risk26,27 and better prognosis of CRC.28 Importantly, IGFBP-3 promoter methylation is observed in many cancers and has been associated with poor clinical outcome. However, the possible prognostic value of IGFBP-3 methylation in PTs or LNs for tumor recurrence after surgical resection of early-stage CRC is unknown. Therefore, we assessed the influence of IGFBP-3 methylation on recurrence in patients with stage II CRC in 2 independent set studies.