Better Lymph Node Analysis May Improve Colon Cancer Treatment

WEDNESDAY, June 21, 2006 (HealthDay News) -- Examining a colon cancer patient's lymph nodes may help doctors decide on the best treatment while helping them avoid unnecessary therapies, a new study shows.

Doctors routinely remove the nodes during surgery to determine if the cancer has spread to the nodes or not. If the cancer has not yet spread to the lymph nodes, surgery alone may be a sufficient treatment.

"One-third of patients with tumor-free lymph nodes have recurrences, and therefore, adjuvant (supplemental) chemotherapy may be beneficial in these patients," researchers at the John Wayne Cancer Institute and Saint John's Health Center in California explained in a prepared statement. "However, if all node-negative patients are treated, 70 percent will be subjected to unnecessary chemotherapy because surgery alone is curative."

Investigating further, the researchers studied 132 colon cancer patients to see whether analyzing lymph nodes could better predict effective therapy.

The patients in the study had dye injected near their tumors to stain the sentinel (first) lymph nodes. This dye showed the doctors the path by which lymph fluids, which can contain cancer cells, drain from the body's tissues. Then the lymph nodes were removed and studied.

"The sentinel lymph node is the first node to receive lymphatic drainage from a primary anatomical site and is therefore the most likely node to harbor a metastasis," the study authors explained.

Thirty percent of the patients studied had stage I cancer, 41 percent stage II and 29 percent stage III cancer. By analyzing the sentinel nodes, 23.6 percent of the patients had their status changed to a more severe stage. Of the 51 patients whose cancer had metastasized to the lymph nodes, researchers found tumors in the sentinel nodes of 45 patients, and found tumors in a total of 18 percent of the sentinel nodes. Only 6 percent of other lymph nodes were diagnosed with tumors. There was a false-negative rate of only 7.4 percent.

The researchers concluded that "lymphatic mapping and sentinel lymph node techniques are feasible and accurate in colon cancer... avoiding the unnecessary toxic effects and expense for those cured by surgery alone."

Results of the study are published in the June issue of Archives of Surgery.

More information

The American Cancer Society has more information on colon cancer.