Dana Farber. US: According to a new study led by researchers at Dana-Farber Cancer Institute, clinical trial patients with metastatic colorectal cancer
who had high levels of vitamin D in their bloodstream prior to
treatment with chemotherapy and targeted drugs, survived longer, on
average, than patients with lower levels of the vitamin. Those findings
were reported today at the 2015 American Society of Cancer Oncology
(ASCO) Gastrointestinal Cancers Symposium in San Francisco.
The
research, based on data from more than 1,000 patients with metastatic
colorectal cancer who enrolled in a phase 3 clinical trial of
chemotherapy plus biologic therapies, adds to vitamin D’s already
impressive luster as a potential cancer-inhibiting agent. In the study,
patients with the highest blood levels of vitamin D survived for a
median period of 32.6 months, compared to 24.5 months for those with the
lowest levels.
“This is the largest study that has been
undertaken of metastatic colorectal cancer patients and vitamin D,” said
the study’s lead author, Kimmie Ng, MD, MPH, a medical oncologist in the Gastrointestinal Cancer Treatment Center
at Dana-Farber. “It’s further supportive of the potential benefits of
maintaining sufficient levels of vitamin D in improving patient survival
times.”
The study didn’t examine whether there is a biological
cause-and-effect relationship between higher vitamin D levels and
extended survival. As a result, researchers said, it’s too early to
recommend vitamin D as a treatment for colon cancer. Ng and colleagues
at Dana-Farber are conducting clinical trials to further investigate
whether vitamin D supplementation is useful in treating the cancer.
In
the study, researchers measured blood levels of 25-hydroxyvitamin D, a
substance produced in the liver from vitamin D, in 1,043 patients when
they enrolled in a phase 3 trial of three different drug combinations
for newly diagnosed, advanced colorectal cancer. Patient vitamin D
levels ranged from an average of 8 nanograms/milliliter (ng/mL) in the
lowest group to an average of 27.5 ng/mL in the highest group. The
average level in all the patients was 17.2 ng/mL. Current practice
guidelines from the Endocrine Society define vitamin D deficiency as
having less than 20 ng/mL.
Researchers divided the patients into
five groups based on vitamin D levels. On average, those with the
highest levels survived 33 percent longer than those with the lowest
(32.6 months vs. 24.5 months). Higher vitamin D levels were also
associated with longer time to disease progression (12.2 months vs. 10.1
months).
Because high vitamin D levels can be a reflection of a
healthy lifestyle (good nutrition, plenty of outdoor physical activity),
researchers controlled for factors such as diet, obesity, and level of
physical activity. Even then, the relationship between elevated vitamin D
levels and extended survival held firm, Ng observed.
The research
was supported by grants from the National Cancer Institute of the
National Institutes of Health (K07 CA148894, R01 CA149222, CA31946,
CA33601).
The senior author of the
study is Jeffrey Meyerhardt, MD, MPH, of Dana-Farber. Co-authors are
Kaori Sato, MS, Robert J. Mayer, MD, and Charles S. Fuchs, MD, MPH, of
Dana-Farber; Alan Venook, MD, of the University of California at San
Francisco; Bruce Hollis, PhD, of the Medical University of South
Carolina; Donna Niedzwiecki, PhD, and Cynthia Ye, PhD, of Duke
University; I-Wen Chang, MD, of Wayne Memorial Hospital, Goldsboro,
N.C.; Bert O’Neil, MD, of Indiana University Hospital; Federico
Innocenti, MD, PhD, of the University of North Carolina; Heinz-Josef
Lenz, MD, of the University of Southern California; and Charles Blanke,
MD, of Oregon Health and Science University.