Personalized Colon Cancer Therapy

What if there was a test that could determine the best treatment regimens for your specific tumor? How about a test that could tell you how likely you are to have a cancer recurrence? A decade ago, doctors could only dream of such tests. But in the not-too-distant future, they will probably be the mainstay of cancer care.

These developments reflect changes in the way scientists think about cancer. Initially, researchers believed that cancer was just one disease and that all cancers could be treated in virtually the same way. Now we know that's not the case. Not only does colorectal cancer differ from, say, breast or pancreatic cancer, but the latest research demonstrates that all colorectal cancers are not the same disease biologically, either.

This, in turn, is changing the way we think about colorectal cancer care. The more we learn about the different types of tumors, the clearer it becomes that not all tumors will respond in the same way to treatment regimens. Instead, the treatment must be tailored to the tumor's specific characteristics. Your doctor might refer to this new era of cancer care as personalized medicine; others call it individualized therapy, tailored treatment, or genome-based medicine. Each term refers to the same process: using genetic information obtained from your tumor to assess which treatment plan is best for you.

Biological Markers --
To move fully into this era of personalized medicine, scientists must first identify the biological markers -- measurable characteristics, like a protein level or the presence or absence of a certain gene or gene mutation -- that can tell us about your tumor's personality. These markers fall into two broad categories: predictive and prognostic.

Predictive biomarkers provide information about which chemotherapy regimens or biological agents might be effective against your tumor and which might not be effective at all.

Prognostic biomarkers assess how likely it is that your tumor is aggressive and, in turn, how likely it is to spread or recur. If you have an aggressive tumor, you may need more or different types of treatment than if your tumor is one that can be cured successfully by surgery alone. Prognostic markers could also be used in conjunction with predictive markers to determine the type of chemotherapy you need.
KRAS: The First Predictive Biomarker -- The National Comprehensive Cancer Network's treatment guidelines now recommend that if you are diagnosed with metastatic colorectal cancer and are a candidate for anti-epidermal growth factor receptor (EGFR) therapy, your tumor tissue should be tested for a predictive biomarker called KRAS, or K-ras. KRAS is a gene that helps tumors grow by sending signals to the cell nucleus through the EGFR on the cell's surface.

MACC1:
A Possible Prognostic Biomarker? A German research group recently reported that it had identified a gene, called metastasis-associated in colon cancer 1 (MACC1), that promotes rapid tumor growth and encourages cancer to spread to additional organs throughout the body. Early studies suggest that if your tumor has high levels of MACC1 you are at a much greater risk for developing metastatic cancer and should consider more aggressive treatment and closer monitoring than someone whose tumor has low levels of MACC1. Larger studies will need to be done to confirm these findings. However, if the results are reproduced, we might see a day when treatment decisions are influenced by a tumor's MACC1 level.


Posted in Colon Cancer on August 11, 2010