With regard to younger women with nonmetastatic breast cancer, 70% received adjuvant chemotherapy. The study is published online in Cancer, a journal of the American Cancer Society.

Determinants of receiving cancer treatment have mostly focused on patient-related factors, such as race/ethnicity, geographic location, age, and socioeconomic status.

 Relatively less research has evaluated the role of the physician and practice setting in the receipt of cancer care.

In this study, the researchers investigated the association of oncologist characteristics, such as gender, type of degree, year of graduation and practice setting -- private vs. non-private -- with receipt of adjuvant chemotherapy for elderly patients with early stage breast cancer.

Women aged 65 years or older, who were diagnosed with stages I to III breast cancer between 1991 and 2002 were studied, and of 42,544 women identified, 8714 (20%) were treated with adjuvant chemotherapy.

"The most powerful predictor of adjuvant chemotherapy was whether the oncologist was in private practice or not," says Dawn Hershman, MD, assistant professor of Medicine at Columbia College of Physicians & Surgeons and assistant professor of Epidemiology at the Mailman School of Public Health, and first author on the study.

"We were surprised to see the strong and consistent relationship between practice setting and chemotherapy use, and even more surprised to see that this association was similar both for patients with a clear indication to high recurrence risk, as well as for those who were likely to have only minimal benefit."

Dr. Hershman suggests the fact that patients at low risk for cancer recurrence, those with estrogen/progesterone receptor positive, stage I/II disease, received treatment regardless of risk factor, could relate to patient volume -- since oncologists in private practice generally have a higher patient volume, or it could be due to patient selection factors -- patients often choose to see physicians for chemotherapy in private settings for convenience, noting that "those with more complicated medical conditions often are treated at university hospitals," says Dr. Hershman.

Patient insurance status also may play a role, she observes, since "research has shown that payment mechanisms do, in fact, influence physicians' clinical decision making."

"A less honorable possibility is that recommendations for chemotherapy are influenced by considerations of financial reimbursement and personal compensation that ensue from chemotherapy administration," suggests Alfred I. Neugut, MD, PhD, professor of Epidemiology at the Mailman School of Public Health, professor of Medicine and head of Cancer Prevention and Control for the Herbert Irving Comprehensive Cancer Center, and the study's senior author.

 "While the majority of oncologists are motivated by patient desires, the potential for conflict of interest in the system has raised concerns, and has resulted in proposals to regulate the reimbursement system."

However, Dr. Neugut notes, one must also consider that patients do, in fact, play a large role in the ultimate decision to undergo treatment with adjuvant chemotherapy.

Acceptance of adjuvant chemotherapy by a woman with breast cancer occurs often after an assessment of risk and benefit, a process referred to as "shared decision making."

The researchers further found that women who underwent chemotherapy were more likely to be treated by oncologists who graduated after 1975 and were less likely to have an oncologist trained in the United States.

###

Other authors on the study included Donna Buono, Russell McBride, and Wei-Yann Tsai of the Mailman School of Public Health.

The research was funded by the American Cancer Society and National Cancer Institute.

About the Mailman School of Public Health

The only accredited school of public health in New York City and among the first in the nation, Columbia University Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting millions of people locally and globally.

The Mailman School is the recipient of some of the largest government and private grants in Columbia University's history.

Its more than 1000 graduate students pursue master's and doctoral degrees, and the School's 300 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as infectious and chronic diseases, health promotion and disease prevention, environmental health, maternal and child health, health over the life course, health policy, and public health preparedness. www.mailman.columbia.edu