Among patients with Stage II or Stage III colon cancer, the Oncotype DX colon cancer test provides information about risk of cancer recurrence and may help guide treatment decisions. These results were presented at the 2012 Annual Meeting of the American Society of Clinical Oncology.

Gene expression profiling explores the patterns of genes that are active in tumor cells. Studies suggest that gene expression may provide important information about prognosis or likely response to treatment in several types of cancer. For example, among women with early-stage, estrogen receptor-positive breast cancer, the Oncotype DX breast cancer test has been shown to predict the likelihood of cancer recurrence and the likelihood of benefit from chemotherapy. As a result, the test has been added to medical guidelines for early-stage breast cancer.

A similar test became available for colon cancer patients in 2010. The test was originally developed for use in patients with Stage II colon cancer, but has now also been validated among patients with Stage III colon cancer. The test evaluates 12 genes in a sample of tumor tissue and generates a Recurrence Score. The Recurrence Score provides information about the likelihood of cancer recurrence.

To further assess the ability of the test to predict recurrence risk among patients with Stage II or Stage III colon cancer, researchers evaluated 892 patients. The patients were enrolled in a clinical trial that assessed two different approaches to adjuvant (post-surgery) chemotherapy: patients were treated with 5FU/LV alone or in combination with oxaliplatin. The addition of oxaliplatin increased effectiveness, but also increased side effects.

• The Recurrence Score predicted recurrence risk in both Stage II and Stage III colon cancer.
  • Among 5FU-treated patients with Stage II cancer, the five-year risk of recurrence was 9% among those with a low Recurrence Score, 13% among those with an intermediate Recurrence Score, and 18% among those with a high Recurrence Score.
  • Among 5FU-treated patients with Stage IIIA/B cancer, the five-year risk of recurrence was 21% among those with a low Recurrence Score, 29% among those with an intermediate Recurrence Score, and 38% among those with a high Recurrence Score.
  • Among 5FU-treated patients with Stage IIIC cancer, the five-year risk of recurrence was 40% among those with a low Recurrence Score, 51% among those with an intermediate Recurrence Score, and 64% among those with a high Recurrence Score.
• The Recurrence Score remained an important predictor of risk even after accounting for other characteristics of the cancer.
• In addition to predicting the risk of recurrence, the Recurrence Score also provided information about overall survival.
• When looking at the benefit of adding oxaliplatin, the absolute benefit (but not the relative benefit) was greater for patients with higher Recurrence Scores.

These results confirm that the Oncotype DX colon cancer test provides information about risk of recurrence among patients with Stage II and Stage III colon cancer, and the test is now available for patients with both stages of disease.

Reference: O’Connell M, Lee M, Lopatin M et al. Validation of the 12-gene colon cancer recurrence score (RS) in NSABP C07 as a predictor of recurrence in stage II and III colon cancer patients treated with 5FU/LV (FU) and 5FU/LV+oxaliplatin (FU+Ox). Paper presented at: 2012 Annual Meeting of the American Society of Clinical Oncology; June 1-5, 2012;Chicago,IL. Abstract 3512.

Tags: Adjuvant (I-III, A-C) Colon Cancer, Colon Cancer, News Tips and Features