Jeffrey Meyerhardt, MD, MPH, co-investigator on the trial.
The combination of chemotherapies 5FU and oxaliplatin compared to 5FU
alone after surgery for colon cancer decreases colon cancer recurrence
and promotes longer survival for patients under 70 — but not for those
who are older, according to Mayo Clinic and Dana-Farber Cancer Institute
scientists who will present their findings at the American Society of
Clinical Oncology's (ASCO) annual meeting in Orlando, Fla.
"By combining information about many patients from a collection of
studies, our analysis determined that the more aggressive combination
chemotherapy does not benefit older colon cancer patients as it does for
those who are younger," said Nadine Jackson McCleary, MD, PhD,
Dana-Farber gastrointestinal oncologist and the lead author on the
study. Jackson-McCleary is the recipient of a 2008-2009 ASCO Young
The data (abstract 4010) will be presented on Saturday, May 30, 3 p.m. ET (Level 2, West Hall D2).
Adding oxaliplatin to chemotherapy treatment with 5FU reduces the
risk of recurrence among patients less than 70 years of age who have had
their primary cancer removed, the study determined, a finding that was
expected based on the results of previous individual trials. Patients
under 70 who were treated with 5FU and oxaliplatin had improved
disease-free survival, with the addition of oxaliplatin relatively
reducing the risk of recurrence or death by approximately 15 percent.
Those patients aged 70 and older who were treated with the combined drug
therapy, however, did not have improved outcomes compared to patients
who received 5FU alone.
"We found that adding chemotherapy agents to the standard 5FU regimen
in older patients after surgery did not provide the benefits that
younger patients see," Dan Sargent, PhD, Mayo Clinic, a collaborator on
the study, agreed. "For the older patient, this means that it is
appropriate to choose the better tolerated treatment strategy of 5FU
The benefit of post-surgical treatment for both young and older colon cancer patients with 5FU was documented in a 2001 New England Journal of Medicine
study by Sargent and colleagues. By 2003, however, oxaliplatin was
approved for use in combination with 5FU because the combination boosted
the impact of 5FU on extending disease-free survival after colon cancer
surgery. While the combined treatment carried additional risk of side
effects, physicians prescribed the treatment strategy to patients of all
ages. Initially, studies that examined age-related impact of the
aggressive chemotherapy combination did not indicate a difference in
survival or recurrence related to patient age.
The current study presented at the ASCO annual meeting includes a
large enough patient base to powerfully discern differences related to
age that are due to treatment regimen.
"The younger patients do get an additional boost from both drugs used
together," Jackson McCleary noted. "Older patients don't benefit from
that combination of treatment."
The findings arise from analysis of combined data collected within an
expanded database by the Adjuvant Colon Cancer End Points (ACCENT)
Group, a consortium of scientists. The ACCENT database includes data
from more than 33,500 patients from the United States, Canada,
Australia, and Europe. ACCENT is supported by the North Central Cancer
Treatment Group (NCCTG); Sargent is chair of ACCENT.
"At this point we can only speculate as to why older patients do not
benefit from combined chemotherapies," Jeffrey Meyerhardt, MD, MPH, of
Dana-Farber and co-investigator on the trial said. "We do know that a
higher number of older patients have to stop the drug before completing
the full six month prescribed course of treatment."
"These studies add to the knowledge base that defines how to choose
treatment strategies for every individual patient," Sargent said. "Age
may become as important a consideration as tumor-specific factors when
defining individual medical options for colorectal cancer patients."
Approximately half of all colon cancer patients are older than 70.
While about half of the colon cancer patients over 70 will live for five
years, those with recurrence typically develop additional tumors within
three years. The disease is diagnosed in a million people worldwide
every year. In the United States, colorectal cancer accounts for 10
percent of new cancer cases, as well as 10 percent of cancer-related
deaths every year.
Jackson McCleary, Meyerhardt, and Sargent conducted the analysis on
the expanded database in concert with an international team of
scientists participating in ACCENT, including Erin Green, MD, Mayo
Clinic; Greg Yothers, PhD, University of Pittsburgh; Aimery de Gramont,
MD, Hôpital Saint-Antoine, Paris; Eric Van Cutsem, MD, PhD, University
of Leuven, Belgium; Michael O'Connell, MD, Mayo Clinic; Chris Twelves,
MD, St James University Hospital, Leeds, England; and Leonard Saltz, MD,
Memorial Sloan-Kettering Cancer Center, New York.
About Dana-Farber Cancer Institute
Dana-Farber Cancer Institute (www.dana-farber.org)
is a principal teaching affiliate of the Harvard Medical School and is
among the leading cancer research and care centers in the United States.
It is a founding member of the Dana-Farber/Harvard Cancer Center
(DF/HCC), designated a comprehensive cancer center by the National
About Mayo Clinic
Mayo Clinic is the first and largest integrated, not-for-profit group
practice in the world. Doctors from every medical specialty work
together to care for patients, joined by common systems and a philosophy
of "the needs of the patient come first." More than 3,300 physicians,
scientists and researchers and 46,000 allied health staff work at Mayo
Clinic, which has sites in Rochester, Minn., Jacksonville, Fla., and
Scottsdale/Phoenix, Ariz. Collectively, the three locations treat more
than half a million people each year. To obtain the latest news releases
from Mayo Clinic, go to www.mayoclinic.org/news. For information about research and education, visit www.mayo.edu. MayoClinic.com is available as a resource for your health stories.
NCCTG is a national clinical research group sponsored by the National
Cancer Institute, comprised of a network of more than 1,000
community-based cancer treatment clinics in the United States and Canada
that work with Mayo Clinic to conduct clinical studies for advancing