MINNEAPOLIS / ST. PAUL, Minn. (Feb. 1, 2005) — Two cancer groups recommend that a minimum of 12 lymph nodes be evaluated in colorectal cancer patients to determine if the cancer has spread. However, a University of Minnesota Cancer Center study, which will be published in the Feb. 2 issue of the Journal of the National Cancer Institute, finds that despite improvement since 1988, only about 44 percent of patients who underwent colorectal cancer surgery in the United States in 2001 had 12 or more lymph nodes evaluated.

Does this imply a majority of colorectal cancer patients may not receive adequate lymph node evaluations? The answer is mixed, says Nancy Baxter, M.D., Ph.D., colon and rectal surgeon with the University of Minnesota Cancer Center and Medical School, who led this research study.

"On the one hand, lymph node status is the strongest predictor of a colorectal cancer patient's outcome and dictates the type of treatment a patient may need after surgery," says Baxter. "Surgeons and pathologists need to make every effort to evaluate 12 or more lymph nodes to determine the correct stage of the disease and the additional treatment required.

"On the other hand, the number of lymph nodes in a given patient varies and some patients actually have fewer than 12 lymph nodes present," she says.

So, what needs to be done?

"Clearly, we need to improve lymph node evaluations in colorectal cancer patients in the United States," says Baxter. "However, this issue needs to be researched further to understand the factors that affect lymph node evaluation. This may involve studying the practice patterns of surgeons and pathologists, as well as investigating patient factors that may influence adequacy of node evaluation. Then we can develop strategies and processes to ensure that every colorectal cancer patient has adequate lymph node evaluation."

Baxter suggests that patients undergoing colorectal cancer surgery select a surgeon qualified in colon and rectal surgery by asking about the surgeon's training and experience in performing colon and rectal surgeries, noting that more surgeries performed usually indicates greater expertise. She also suggests patients ask their surgeon after the surgery how many lymph nodes were removed for evaluation by the pathologist.

Baxter uncovered this quandary during a review of national data on 116,995 adults, evenly divided on the number of men and women, who underwent radical surgery for colorectal cancer from 1988 through 2001. She reviewed the number of lymph nodes removed from each patient for evaluation, whether the number met the recommended standard of 12 lymph nodes be examined, and the role the tumor and other patient factors had in the evaluation.

Baxter found:

• The average number of lymph nodes evaluated was nine, instead of the minimum 12 recommended by the International Union Against Cancer and the American Joint Committee on Cancer.
• The proportion of patients receiving evaluation of 12 lymph nodes increased from 32 percent in 1988 to 44 percent in 2001.
• Younger patients were more likely than patients 70 years or older to have 12 or more lymph nodes evaluated.

Lymph nodes are about the size of peas or beans and contain clusters of cells. Located throughout the body, lymph nodes filter out and fight off bacteria, infections, and cancer cells.

Adequate evaluation of lymph nodes is an important matter because colorectal cancer is the second leading cause of cancer death in the United States, annually claiming about 57,000 lives. About 150,000 people are diagnosed with the cancer each year and a mjority of them are told they need surgery.

Evaluations of the lymph nodes guide the physician in determining the course of further treatment. If cancer has spread to the lymph nodes, chemotherapy can improve survival and is generally recommended.

For example, Baxter says, the number of lymph nodes evaluated has been found to be a particularly important predictor in patients with stage II colorectal cancer.

"For patients classified with stage II disease, the 5-year survival rate was 64 percent when one or two lymph nodes were evaluated but 86 percent when more than 25 nodes were sampled," Baxter explains.

"This indicates that inadequate lymph node evaluation can have serious implications," she says. "It can lead to positive lymph nodes being missed or patients being inappropriately classified as having lymph node-negative disease. Such patients may not be given the opportunity to benefit from additional therapy. Furthermore, inadequate lymph node evaluation may result in the failure to remove lymph nodes containing cancerous cells, thus increasing the risk of recurrence."

Most importantly, the results of this study indicate that this issue needs to be reckoned with, Baxter says.

Data for this study came from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program. Working with Nancy Baxter, M.D., Ph.D., on conducting this study were Dan Virnig, M.D.; David Rothenberger, M.D.; Arden Morris, M.D., M.P.H.; Jose Jessurun M.D.; and Beth Virnig, M.P.H., Ph.D.

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Media Contact: Mary Lawson, Public Relations Director, University of Minnesota Cancer Center, 612-624-6165, 612-363-6971 (cell), mlawson@umn.edu.