New calculator provides more accurate estimates of colon cancer survival

04/02/04

Tool can aid physicians in making treatment decisions with patients

ROCHESTER, Minn. -- A new calculator tool can help physicians provide colon cancer patients with more accurate, individualized five-year disease-free and overall survival estimates with surgery alone and with additional chemotherapy treatment.

The calculator tool was developed by an international team of researchers, co-led by Charles Loprinzi, M.D., and Sharlene Gill, M.D. Dr. Loprinzi is a medical oncologist at Mayo Clinic and program leader of the Cancer Control Program for Mayo Clinic Cancer Center in Rochester, Minn.; Dr. Gill is at the British Columbia Cancer Center in Vancouver, Canada.

The report explaining the tool, entitled "Pooled Analysis of Fluorouracil-Based Adjuvant Chemotherapy for Stage II and III Colon Cancer: Who Benefits and by How Much," will be published April 5 on the Internet site of the Journal of Clinical Oncology, www.jco.org.

"Most newly-diagnosed cancer patients consistently report that they want information about their likelihood of a cure, and most prefer both qualitative and quantitative information when making decisions about their course of treatment," says Dr. Loprinzi. "At the same time, variations and uncertainty exist when estimating prognoses for cancer patients. As a result, patients may not get the information they want, or they may misunderstand the risks of their disease and the reasons for considering the use of chemotherapy after colon cancer surgery."

Previously conducted clinical trials have clearly demonstrated that chemotherapy after surgery can improve cure rates for various groups of patients with colon cancer.

"Our intent with this calculator is to help clarify the situation by providing physicians with a tool for more accurately estimating a colon cancer patient's prognosis," says Dr. Gill. "Physicians can then use this information as appropriate to help their patients make more informed decisions about an individual patient's probability of being cured of stage II or III colon cancer through surgery alone, and how much chemotherapy after surgery will improve their chances of staying free of recurrent colon cancer."

An estimated 106,000 people in the United States will be diagnosed with colon cancer this year. About 60,000 of those patients may be candidates for adjuvant chemotherapy after surgery.

The computer program used by the calculator is based on pooled data from 3,302 patients who had surgically-resected stage II and III colon cancer and had participated in one of seven different clinical trials. All of these patients had all known cancer removed by surgery.

However, each was considered at substantial enough risk for recurrent colon cancer to warrant participating in a clinical trial to test whether additional treatment might increase the chance of cure. The patients were randomly assigned to no further treatment or to receive chemotherapy consisting of fluorouracil (5-FU) with leucovorin or with levamisole.

To use the calculator, physicians enter information about four factors that impact treatment options and prognosis: 1) The number of positive, or cancer-affected, lymph nodes, 2) The depth of the tumor through the bowel wall, 3) The grade of the tumor (determined by looking at the cancer under the microscope), and 4) The age of the patient. The calculator then computes the chances of the colon cancer not returning and of the patient being alive five years after treatment, both with surgery alone and with surgery plus adjuvant chemotherapy treatment.

An example of a reasonably favorable outcome involving adjuvant chemotherapy after surgery for colon cancer includes the following:

Information entered: Number of positive lymph nodes -- No positive nodes
Depth of tumor (T stage) -- T3
Grade of tumor -- Low
Age -- 49 or younger

Information generated by the computerized calculator:
* Five-year recurrence-free survival:
Baseline prognosis with surgery alone -- 73%
Prognosis with surgery and adjuvant 5-FU -- 77%
* Five-year overall survival:
Baseline prognosis with surgery alone -- 83%
Prognosis with surgery and adjuvant 5-FU -- 85%

An example of a less favorable outcome includes the following:

Information entered:
Number of positive lymph nodes -- 5 or more
Depth of tumor (T stage) -- T3
Grade of tumor -- Low
Age of patient -- 49 or younger

Information generated by the computerized calculator:
* Five-year recurrence-free survival:
Baseline prognosis with surgery alone -- 24%
Prognosis with surgery and adjuvant 5-FU -- 43%
* Five-year overall survival:
Baseline prognosis with surgery alone -- 40%
Prognosis with surgery and adjuvant 5-FU -- 56%

According to Dr. Loprinzi, the calculator may be modified as new prognostic information and as data about additional benefits from newer adjuvant chemotherapy regimens become available.

For instance, he says, "If a physician is convinced that a newer chemotherapy regimen is more beneficial than the ones studied in the randomized clinical trials we reviewed, then appropriate data can be entered into the calculator to individualize estimates for patients."

Dr. Loprinzi emphasized that this calculator is intended only for estimates of survival. "It is an aid for making decisions about adjuvant chemotherapy treatment, and, as with all prognostic tools, the information is to be interpreted within the context of the individual patient's situation by the patient's oncologist."

This is the third such calculator developed by Dr. Loprinzi and research colleagues; similar tools have been created for estimating outcomes for patients diagnosed with breast cancer and melanoma.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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