Chemotherapy following surgery improves survival for patients with stage III colon cancer, and chemotherapy combined with radiation therapy following surgery improves survival for patients with stage II or III rectal cancer. Yet, only two-thirds of potentially eligible patients with colorectal cancer in California received adjuvant chemotherapy and radiation therapy, according to a study supported by the Agency for Healthcare Research and Quality (HS09869).
Although some patients will refuse these treatments or have clear clinical contraindications, treatment rates of 80 percent or greater are attainable in community practice, says John Ayanian, M.D., M.P.P., of Harvard Medical School. This suggests that these evidence-based therapies may be underused despite a national consensus endorsing them.
Dr. Ayanian and his colleagues used the California Cancer Registry to identify 1,422 patients diagnosed during 1996 to 1997 with stage III colon cancer and 534 patients diagnosed with stage II or III rectal cancer. They also surveyed physicians or reviewed office records for 1,449 of these patients to determine therapy use and reasons for not using therapies. Adjusting for demographic, clinical, and hospital characteristics, chemotherapy was used less often among older and unmarried patients, and radiation therapy was used less often among older patients, black patients, and those initially treated in hospitals that cared for a low volume of colorectal cancer patients.
Adjusted rates of chemotherapy varied significantly among individual hospitals: 79 and 51 percent, respectively, at hospitals that were one standard deviation above and one standard deviation below the average of 67 percent. Reasons given by physicians for not providing adjuvant chemotherapy or radiation therapy included patient refusal (30 percent and 22 percent, respectively), coexisting illness (22 and 14 percent, respectively), or lack of clinical indication (22 and 45 percent, respectively). However, over 40 percent of doctors perceived that chemotherapy was not indicated for stage II rectal cancer or that radiation therapy was not indicated for stage II or III rectal cancer, despite widely publicized guidelines supporting the use of these therapies.
More details are in "Use of adjuvant chemotherapy and radiation therapy for colorectal cancer in a population-based cohort," by Dr. Ayanian, Alan M. Zaslavsky, Ph.D., Charles S. Fuchs, M.D., M.P.H., and others, in the April 1, 2003, Journal of Clinical Oncology 21(7), pp. 1293-1300.
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