Gene Panel May Predict Who Needs Rectal Cancer Surgery

Surgeons at M.D. Anderson Cancer Center in Houston have identified 87 genes that someday may tell doctors whether or not rectal cancer patients need surgery after chemotherapy and radiation. The panel of genes predicted patients whose cancer appeared to be completely destroyed by the combination of chemotherapy and radiation before surgery, what is called pathological complete response.

Before it can become routine practice, the gene panel will need to be checked in another group of patients and clinical trials will need to be conducted to see if patients who have pathological complete responses and no surgery do as well as those who do have surgery.

After presurgical chemoradiation treatments, about 1 in 5 rectal cancer patients will have all signs of cancer disappear in pathology tests after surgery. But surgeons don’t know which patients those are until they operate and remove the rectal tumor and its attached tissue and lymph nodes.

M.D. Anderson researchers assessed gene expression in tumor tissue from 46 patients with locally advanced rectal cancer. They found that the expression of 87 genes was more common in those patients who had no cancer cells remaining in rectal tissue removed during surgery.

Currently standard treatment for locally advanced rectal cancer is chemotherapy and radiation followed by surgery to remove part of the rectum. If the gene profile could identify patients who would have complete responses and clinical trials showed that not doing surgery was as effective as surgery in those patients, some patients with rectal cancer could be spared the risks, pain, and potential long-term effects of surgery.

Isabelle Bedrosian, MD, FACS, assistant professor of surgery at the University of Texas M.D. Anderson Cancer Center, explained,

We typically say that patients need chemotherapy, radiation therapy, and surgery to get the best outcomes. The upfront chemotherapy and radiation therapy helps shrink tumors down so they can be more easily removed surgically and decreases the chance that the tumor will come back in the pelvis.

Dr. Bedrosian continued,

Findings from this study suggest that we may have a new tool to say to a patient whose tumor has a specific DNA profile and who has had a complete clinical response to chemotherapy and radiation therapy that he may not need radical surgery.

Plans are underway to validate the gene panel in another group of patients. If successful, clinical trials can be planned to compare recurrences and survival between groups of patients, whose tumors fit the gene profile, who do and do not have surgery.

Dr. Bedrosian’s study was reported at the American College of Surgeons Clinical Congress last week in Chicago.

What This Means for Patients

Discovering the genes that appear to predict pathological complete response is only the first step. The genes will need to be independently verified in another group of patients. Then randomized clinical trials will be necessary to see if outcomes like cancer returning in or near the rectum or cancer-free survival are the same whether or not patients have surgery.

So the gene testing is not yet ready for use in today’s patients.

This news article was originally posted on October 20th, 2009 and was accurate at the time of publication. Since then, information may have changed or links may now be outdated. Please call our Answer Line 1-877-427-2111 for the latest information, or talk to your doctor before making any medical decisions.

Posted by Kate Murphy on October 20th, 2009
Tags: chemoradiation, pathological complete response, rectal cancer