James P. Stevenson, MD
Last Modified: November 1, 2001
Dear OncoLink "Ask the Experts,"
I understand that the presence or absence of some genes makes a significant difference in the effectiveness of therapies such as radiation and chemo. Is there a current test to determine whether these genes are present in an individual? I had Stage B colon cancer, last year, age 64, but I elected not to have chemo following surgery.
James P. Stevenson, MD, Assistant Professor of Medicine in the Hematology/Oncology Division of the University of Pennsylvania School of Medicine, responds:
There are some genes that can be tested for in colon cancer surgery specimens that may provide information regarding prognosis and predict response to treatment. Two of the genes currently under investigation are called DCC and p53. There is conflicting data regarding using p53 to predict response to therapy and overall prognosis. Early studies show DCC may be an important marker in evaluating patients in the future, but intensive investigation continues. Neither of these genes are routinely evaluated in surgical specimens and would need to be done by a specialized lab.
The most important factor regarding prognosis is the presence or absence of cancer in lymph nodes from the surgical specimen. For example, although we cannot comment on your specific case, assuming that the staging information you have presented is correct and complete, Dukes B colon cancers (no lymph node involvement) have a very good prognosis. We know that most people with node-negative cancers do not benefit from post-operative chemotherapy, so a decision not to have chemotherapy after surgery is a reasonable one.
Current recommendations are continued close follow-up with an oncologist or surgeon (every 3 months), with blood work (including a CEA test) performed at each visit, as well as follow-up colonoscopies.