Colon cancer treatment frequently is less aggressive than recommended, study finds

March 16, 2010, RAND Corporation

New results from a major initiative on the quality of cancer care in the United States show that patients with a common type of colon cancer -- especially older patients -- often are not treated as aggressively with chemotherapy as research shows is necessary to improve survival.

Led by researchers from the RAND Corporation and UCLA, the study is among the first to track how findings from specialty research trials are applied in diverse practices in the community where a wider variety of patients are treated. Results are being published in the March 17 edition of the devoted to developments in cancer care.

The study suggests that older patients and, to some extent younger ones, receive care that differs from that recommended based upon clinical trials. For patients with stage III (the stage of cancer that has spread to lymph glands), these studies show that patients have less and better survival if they receive chemotherapy to "lock" the patient into a cancer-free state after surgical removal of the cancer. Studies show that the adjuvant chemotherapy helps improve the outlook for patients in all age groups.

"Our team found that patients, especially older patients in community settings, received care that is different in important ways from what is recommended based upon trials conducted in specialty research settings," said Dr. Katherine L. Kahn, an internist at the David Geffen School of Medicine at UCLA, a researcher at UCLA's Jonsson Comprehensive Cancer Center and a senior natural scientist at RAND, a nonprofit research organization. "Better understanding of why this happens is important to improving care for this group of patients."

The findings are from the Cancer Care Outcomes Research and Surveillance study, a multicenter project designed to assess care and outcomes for patients with newly diagnosed colorectal cancers. The project was designed to examine the care cancer patients receive in the diverse care centers in which patients across America receive treatment for colon cancer.

"Because patients who participate in trials of new cancer treatments tend to be younger, healthier, and less diverse socioeconomically than cancer patients in general, it is important to see how well new treatments are adopted in community settings where there is a more diverse mix of patients," Kahn said. The study included patients who spoke English, Spanish or Chinese.

After identifying 4,713 patients with colorectal cancer, researchers analyzed the care received by 675 patients, including 202 people aged 75 and older, who had been diagnosed from 2003 to 2005 with stage III colon cancer and had undergone surgery to remove tumors as well as lymph nodes where cancer was detected.

Researchers found adjuvant chemotherapy use across diverse settings differed from recommendations from clinical trials in four important ways:

  • Despite evidence from trials showing improved outcomes for patients receiving adjuvant chemotherapy regardless of age, only 50 percent of patients aged 75 and older received adjuvant chemotherapy.
  • Starting chemotherapy doses were lower than in standard regimens for 18 percent of patients.
  • Older patients were less likely to receive the strongest chemotherapy that has been shown in clinical trials to be most effective in improving survival: 14 percent of older patients compared to 44 percent of the younger patients received this type of chemotherapy.
  • In contrast to recommendations that a course of adjuvant chemotherapy last six months, only two-thirds of patients were still receiving adjuvant chemotherapy at six months; 40 percent of older patients and 25 percent of younger patients had discontinued treatment by five months.
"Among treated patients, older patients did not experience more adverse outcomes in the year following the cancer diagnosis than younger patients, even after accounting for the additional illnesses that older patients are more likely to have," Kahn said.

Older colon cancer patients who received chemotherapy may have fared so well because those selected for treatment were stronger or because they were given less-intensive chemotherapy regimens, although the RAND-UCLA study also accounted for patients' burden of disease and for chemotherapy start date, strength and duration.

Although the study found that treatment in the community was not consistent with recommendations from clinical trials, researchers do not know if these differences will lead to poorer outcomes. Researchers plan to follow up the cancer patients to learn whether the lower doses and shorter courses of treatment noted in community practice, compared with those in trials, achieve comparable outcomes -- especially older patients treated in diverse settings. In addition, they will examine whether the modified treatment regimens affect cancer recurrence and disease-free survival as expected based upon trial evidence.

"We use the chemotherapy to prevent recurrence and prolong disease-free survival," Kahn said. "At this time, we do not know whether these new regimens will be associated with the significantly lower rate of recurrence and improved survival that has been noted with use of adjuvant chemotherapy in trials."

Researchers say the study provides important insights into the many steps involved in translating science from research settings to community office settings where doctors see most patients with colon cancer.

"It is important to see if new treatments supported by research can be used in community settings where there are diverse groups of patients, not just the young and strong ones that usually voluntary for research studies," Kahn said.

Patients in the cancer study were drawn from three settings: five population-based areas in Alabama, Iowa, Los Angeles County, Northern California, North Carolina; five integrated health care systems; and 15 Veterans Affairs hospitals. They were among the 10,061 patients and their caregivers that have taken part in the federally funded Cancer Care Outcomes Research and Surveillance study of colorectal and lung cancer.

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