And although most of the more than 300 women in the study eventually had recommended chemotherapy, 11 percent did not, the researchers said.
"Previous studies have shown that timely initiation of breast cancer chemotherapy is associated with better breast cancer survival," said lead researcher Heather Greenlee. She is an assistant professor of epidemiology at Columbia University's Mailman School of Public Health in New York City.
The findings show that "women who do not initiate [chemotherapy] are more likely to be users of dietary supplements, and use many different forms of complementary and alternative therapies simultaneously," she said.
"Breast cancer patients and their doctors need to discuss expectations and concerns around chemotherapy, and also talk about motivations and goals for use of complementary and alternative therapies," Greenlee said.
To determine the effect of alternative medicine use on the decision to have chemotherapy, Greenlee and colleagues studied nearly 700 women with early stage breast cancer. All were under the age of 70.
The researchers looked at five types of alternative treatments, including: vitamin and mineral supplements; herbs and botanicals; other natural products (such as fish oil or melatonin); mind-body self-practice (such as yoga and meditation); and practitioner-based mind-body practices (such as acupuncture).
In all, 306 women were advised to undergo chemotherapy. After a year, 89 percent of these women had started treatment. Among the other women, for whom chemotherapy was optional, only 36 percent opted for treatment, the researchers found.
Of all the women in the study, 87 percent said they used some type of alternative therapy, most commonly dietary supplements and mind-body practices. Many women used two alternative therapies, and 38 percent used three or more, the findings showed.
Use of dietary supplements was related to the decision whether or not to have chemotherapy, while the use of mind-body practices was not related to starting chemotherapy, the investigators found. But the study could not prove that using alternative medicine caused these women to delay chemotherapy.
In addition, no association between starting chemotherapy and alternative therapy was found among women for whom chemotherapy was optional, the study authors said.
The report was published online May 12 in the journal JAMA Oncology.
One expert said the findings suggest that doctors need to try harder to communicate the benefits of chemotherapy to these patients.
"While there may be several reasons for using complementary and alternative medicine, a considerable proportion of patients -- in particular those who use dietary supplements -- believe that this will have a beneficial effect on their cancer," said Robert Zachariae, from the department of oncology at Aarhus University Hospital in Denmark. He wrote an editorial that accompanied the study.
Therefore, users of complementary and alternative medicine may be a particularly vulnerable group of patients, Zachariae said.
"Our research has also shown not only that they generally are more depressed than nonusers, but also that continued use -- in particular use of dietary supplements -- is associated with more depressive symptoms over time," he added.
Doctors need to improve their ability to get patients to disclose and discuss their use of complementary and alternative medicine, Zachariae said.
"This requires communication skills that enable them to respectfully and non-judgmentally explore patients' preferences and beliefs about complementary and alternative medicine, and provide the best information about the available treatment options," Zachariae explained.
Visit the American Cancer Society for more on breast cancer.
Copyright © 2016 HealthDay. All rights reserved.