A significant proportion of patients with stage III colon cancer may stop their six-month chemotherapy program early, and early termination of treatment may be equivalent to receiving no chemotherapy at all, according to an article in the May 20 issue of the Journal of Clinical Oncology.

Alfred I. Neugut, MD, PhD, Dawn L. Hershman, MD, and colleagues at Columbia University, New York City, New York, found that as many as 30 percent of patients with stage III colon cancer who were prescribed six months of chemotherapy with 5-fluorouracil and leucovorin stopped treatment prematurely.

Previous studies have shown that not completing chemotherapy regimens for breast cancer is associated with shorter survival. This is the first study to look at a link between mortality rates from colon cancer and treatment adherence.

“The intuitive thinking is that if you complete most of a treatment regimen, you should get most of the treatment benefit. But these findings are significant because they indicate that completing treatment is as critical for colon cancer as it is for breast cancer - and we need to do better to ensure that patients who can, complete treatment as intended,” said Neugut.

The research team used the Surveillance, Epidemiology, and End Results (SEER)-Medicare database to identify stage III colon cancer patients who were at least 65 years of age or older, and who received one to seven months of fluorouracil (FU)-based adjuvant chemotherapy treatment.

Among the 1,579 patients who survived eight months or longer, the 1,091 (69.1 percent) patients who underwent five to seven months of treatment survived nearly twice as long as the 488 (30.9 percent) who received only one to four months of treatment. Patients who were older, unmarried and had comorbid conditions, were more likely to receive less than five months of treatment.

The same research team published an article in September 2005 in the Journal of Clinical Oncology that was the first study to link treatment completion issues with race and poor survival rates.

The 2005 study found that black women with early-stage breast cancer were more likely than their counterparts of other races to abandon chemotherapy before completing the full course of treatment. The findings shed new light on why breast black cancer patients experience lower survival rates than other women, despite a lower incidence.