Jun 11 2012
By Helen Albert
A novel microarray-based 18-gene expression tool known as ColoPrint (Agendia NV, Amsterdam, the Netherlands) significantly improves prognostic accuracy in stage II colon cancer patients who have undergone surgery, suggest study findings.
The researchers, Iris Simon (Agendia NV) and colleagues, say that their results, presented at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, USA, could help clinicians to identify higher-risk patients who might require additional treatment at an early stage to prevent relapse.
Approximately 80% of stage II colon cancer patients are cured by surgery alone, and predicting who is likely to benefit from adjuvant chemotherapy or radiotherapy to prevent relapse can be difficult.
This type of therapy is recommended in high-risk patients, such as those with T4 tumors, but is not recommended for those with lower relapse risk, such as patients with MicroSatellite Instability-High (MSI-H) tumor status. However, there are still many patients with indeterminate risk for relapse, say the researchers.
Drawing on previous experience from the development of MammaPrint (Agendia NV), a similar 70-gene tool designed to help predict breast cancer relapse, the researchers developed ColoPrint to improve relapse risk stratification in stage II colon cancer patients following surgery.
It was produced using whole genome expression data from 188 patients with stage I‑IV colon cancer from which 18 genes with high disease association were selected for inclusion on the microarray.
Following development of the ColoPrint tool, it has been validated in public datasets (stage I‑III; n=322) and in independent patient cohorts from five European hospitals (stage I‑III).
Simon and team used tissue specimens, MSI status, clinical parameters, and a median of 70 months' follow-up data to calculate the ColoPrint index for 335 stage II/IIIA colon cancer patients and 227 T3/MicroSatellite Stable (MSS) colon cancer patients.
In the stage II/IIIA group, ColoPrint classified two-thirds of stage II patients as being at low risk for relapse and one-third as being at high risk. The 3-year relapse-free survival (RFS) was 92% for those in the ColoPrint low-risk group and 77% for those in the high-risk group (hazard ratio [HR]=2.9; p=0.001).
In patients with a T3/MSS phenotype, 61% and 39% were classified as being at low and high risk for relapse, respectively. Of these patients, a corresponding 92.2% and 79.9% had a 3-year RFS (p=0.01).
When more traditional clinical parameters from the ASCO and National Comprehensive Cancer Network (NCCN) recommendations such as T4 tumor status, perforation, assessment of fewer than 12 lymph nodes, high tumor grade, and angiolymphatic invasion were used to determine relapse risk, outcome predictions were similar to those calculated using the ColoPrint index.
Notably, when the ColoPrint index risk assessment and clinical risk assessment (based on ASCO/NCCN factors) were combined, risk assessment improved and those with a ColoPrint and clinical high risk had the highest risk for relapse overall (28%; HR=6.68) compared with those who were classified as ColoPrint and clinical low risk (5%; HR=1.0).
"Treating all stage II patients with chemotherapy is not necessary and not very useful, so it is an important step to identify those patients who might not need chemotherapy, the low-risk patients, and identify those who should get chemotherapy, the high-risk patients," commented Simon.
She confirmed that ColoPrint is now commercially available and is currently undergoing US Food and Drug Administration evaluation.
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