In the Journal of the American Medical Association, the investigators found that patients who received chemotherapy after surgery to treat their advanced colon cancer had a 16 percent improved benefit in relative five-year survival compared with patients who were not treated with chemotherapy. That means these patients had more than a 30 percent increased chance of being alive five years after treatment.
Women and the elderly given chemotherapy had the same benefit, but were significantly less often treated with chemotherapy, according to the research team, led by J. Milburn Jessup, MD, of both Georgetown University Medical Center and the National Cancer Institute.
He says the study results should alert both community-based oncologists and colon cancer patients that chemotherapy is, for most people, a beneficial treatment.
"Our intent in part is to show that since women and elderly do benefit from adjuvant chemotherapy as much as men or younger patients do, then it will reassure both patients and doctors that it is a good thing to do," said Jessup.
"We really hope that this study will result in having both patients and physicians work together to use adjuvant therapy," he said.
The study is unusual because it looked at whether oncologists in the community followed the treatment recommendations issued in 1990 by a NIH consensus conference. These experts found that all patients with stage III colon cancer should be given chemotherapy (a 5-fluorouracil-based regimen) following surgery because several large randomized phase III clinical trials demonstrated improved survival.
They also wanted to determine whether patients over time did, in fact, benefit from use of chemotherapy. Analyzing 12 years of data, the investigators found that chemotherapy did increase survival, but that only two-thirds of patients were receiving this suggested standard of care.
Jessup said the researchers cannot determine why some patients were not given chemotherapy, because they examined only data about patterns of care and survival, but he said "guidelines are just that - they are recommendations for therapy based on objective data from randomized clinical trials but they are not currently enforced."
He added that physicians "pay attention to guidelines from various and assorted organizations but may feel that a particular guideline should not be used for each and every patient. This may be because for this type of guideline the chemotherapy treatment may be toxic and the physician may not feel the patient will really tolerate it or the patient may be offered the therapy and refuse it."
Confounding this issue, Jessup says, is the fact that most patients who enroll in clinical trials are younger and have fewer other "co-morbid" health issues than patients in the community, and so physicians are uncertain that the same benefit extends to older or sicker patients.
Still, he said, results from this study suggest that age and co-morbidity are less important than the benefit from use of chemotherapy. "Since we are not able to track co-morbid conditions in this set of patients, it is possible that many of the patients who did not receive chemotherapy in the last cohort are too ill from other diseases to use chemotherapy," he said. "However, all patients went through the surgery and about half of those who did not receive the adjuvant therapy were well enough to live for 5 years. This suggests that a substantial fraction of those who did not receive adjuvant therapy could in fact do so."
The study also uncovered the surprising fact that African -American colon cancer patients are receiving adjuvant chemotherapy as they should, but are having less success with it.
"The data indicate that when non-Hispanic Whites and African Americans with apparently the same stage of disease are treated with chemotherapy, the African Americans have on average a 7 percent worse survival," Jessup said. "This bears more study."
The study was funded by the American College of Surgeons and the American Cancer Society. Jessup's co-authors include Bruce Minsky, MD, from Memorial Sloan-Kettering Cancer Center, Andrew Stewart, MS, from the American College of Surgeons, and Frederick Greene, MD, from Carolinas Medical Center.
About Georgetown University Medical Center
Georgetown University Medical Center is an internationally recognized academic medical center with a three-part mission of research, teaching and patient care (through our partnership with MedStar Health). Our mission is carried out with a strong emphasis on public service and a dedication to the Catholic, Jesuit principle of cura personalis -- or "care of the whole person." The Medical Center includes the School of Medicine and the School of Nursing and Health Studies, both nationally ranked, the world-renowned Lombardi Comprehensive Cancer Center and the Biomedical Graduate Research Organization (BGRO).