ASCO 2008: Clinicians too cautious in use of chemotherapy for oldest patients with stage III colon cancer

June 2, 2008

Advanced age should not be a barrier to initiating adjuvant chemotherapy in patients with stage III colon cancer. In an observational study, the oldest patients suffered no more adverse events when treated with adjuvant chemotherapy than did younger patients but were much less likely than their younger counterparts to actually receive adjuvant chemotherapy for their colon cancer, said Katherine L. Khan, MD, professor of medicine at the University of California, Los Angeles.

Advanced age should not be a barrier to initiating adjuvant chemotherapy in patients with stage III colon cancer. In an observational study, the oldest patients suffered no more adverse events when treated with adjuvant chemotherapy than did younger patients but were much less likely than their younger counterparts to actually receive adjuvant chemotherapy for their colon cancer, said Katherine L. Khan, MD, professor of medicine at the University of California, Los Angeles.

The study was part of the Cancer Care Outcomes Research and Surveillance Consortium (CanCORS) observational cohort study, in which medical record data were collected from a representative sample of 689 patients with incident stage III colon cancer from 22 clinical sites across the country. Data were collected from the patient or from a surrogate. Surgical resection was performed an average of 12 days after diagnosis, and when started, chemotherapy was administered an average of 62 days after diagnosis. Seventy-five percent of the 689 patients received adjuvant chemotherapy. Forty-two percent of the patients were aged at least 75 years.

"With the elderly being the fastest growing segment of the American population, and the incidence of colon cancer increasing with age, this study asks whether clinicians are too cautious in initiating adjuvant chemotherapy for elderly stage III colon cancer patients," said Dr Khan.

Multiple studies have documented low rates of adjuvant chemotherapy use for colon cancer among older patients despite evidence from randomized controlled trials that older patients experience benefits from treatment, she said.

In this study, chemotherapy use ranged from 89% of patients aged

Two regimens, bolus 5-fluorouracil with leucovorin and FOLFOX (fluorouracil, leucovorin, and oxaliplatin), accounted for 70% of all regimens used. "The FOLFOX regimen was used far more often among younger patients than in those 75 years or older (35% vs 13%, respectively)," said Dr. Khan. The FOLFOX regimen is the preferred regimen for patients with colon cancer.

Overall, beginning 31 days postresection, one-fourth of patients receiving adjuvant chemotherapy suffered 1 or more clinical adverse events, significantly more frequently than patients not treated with chemotherapy.