New colon cancer guidelines

Aug 17 2004

The American Society of Clinical Oncology has developed a set of recommendations to address whether patients who have had successful surgery for Stage II colon cancer should be offered adjuvant chemotherapy in routine clinical practice.

The guideline, published in the August 15 issue of the Journal of Clinical Oncology, states that the routine use of adjuvant chemotherapy for medically fit, average-risk patients with Stage II colon cancer is not recommended. Clinical trials have not established with certainty a significant degree of clinical benefit for adjuvant chemotherapy in patients with Stage II colon cancer, although most trials show a small benefit from adjuvant chemotherapy.

Specifically, patients who receive adjuvant chemotherapy have about a 4% to 5% greater chance of survival five years after surgery, compared with patients who had surgery alone. The exact benefit is not known with certainty because not enough Stage II patients have been included in clinical trials involving this group of patients only.

Patients with Stage II colon cancer also should be encouraged to participate in randomized clinical trials. The guideline includes a section on “Discussion Points” that advises oncologists on how to approach such a discussion with the patient.

“Patients and their families often want black-and-white guidance on how to treat their disease,” said Al B. Benson III, MD, FACP, director of the Robert H. Lurie Comprehensive Cancer Center's Clinical Investigations Program at Northwestern University's Feinberg School of Medicine and lead contributor to the guideline. “Unfortunately, that is not possible with Stage II colon cancer.It is critical for each patient to weigh the risk of therapy and any potential benefit.The ASCO Discussion Points provide an opportunity for the patient and physician to discuss what is known about Stage II colon cancer. By reviewing these points, we feel that the patient will be better able to make an informed decision.”

Doctors usually offer adjuvant chemotherapy to patients with Stage III colon cancer because clinical trials have shown that it helps a proportionally larger number of patients live longer than patients who do not receive adjuvant chemotherapy. But, the data are not as definitive, the increase in cure rate is less in patients with Stage II colon cancer. The reason for this is that even without adjuvant chemotherapy, most patients with Stage II disease will be cured by surgery alone.

The guideline also discusses the importance of evaluating prognostic and predictive markers in high-risk Stage II colon cancer.The guideline highlights the key role of the number of lymph nodes removed with the colon cancer during surgery, and examined by the pathologist, in making decisions about adjuvant chemotherapy.The greater the number of lymph nodes examined, the easier it is to have confidence that the cancer has not spread.

The Panel emphasizes that patients and their doctors should consider the number of lymph nodes that were examined when deciding about adjuvant chemotherapy. The guideline also pointed to other groups of Stage II colon cancer patients—those with certain tumor characteristics that can be identified by a pathologist or by using specialized tests—who might be candidates for chemotherapy.

ASCO has collaborated with Cancer Center Ontario on this guideline and is publishing the guideline in conjunction with the Cancer Care Ontario group's systematic review on Stage II adjuvant chemotherapy.

“This guideline represents one stop along a continuum,” Benson added. “ASCO continually reviews relevant literature and updates guidelines as needed.”

ASCO also released a new evidence-based patient guide, Adjuvant Chemotherapy for Stage II Colon Cancer. The guide is the patient version of the clinical practice recommendations.