January 2007 - Two new studies by researchers at the University of Rochester Medical Center and the University of Michigan published in the Journal of Clinical Oncology review the records of 764 women enrolled in the Awareness of Neutropenia in Chemotherapy (ANC) Study Group Registry.
The women received treatment for breast cancer between 2002 and 2005 at 115 randomly selected, private oncology practices. Researchers analyzed detailed information including patients' age, education, insurance coverage, zip code, height, weight, treatment plan and chemotherapy received compared to recommended protocols. They compared findings with US Census Bureau data for each geographic area.
Findings indicate that women with breast cancer who are obese, less educated or have lower household incomes may be more likely to receive reduced doses of chemotherapy thereby jeopardizing their survival. Researchers cite American Cancer Society projections that more than 200 000 women in the US will be diagnosed with breast cancer in 2007 and about 41 000 will die from the disease.
Researchers explain that under treatment is well-documented, with oncologists sometimes reluctant to deliver recommended doses of chemotherapy to obese women because of concern about possible adverse side-effects, despite indications that it is appropriate and safe. Other reports identify wide variations in oncology practice between different regions of the US. Previous studies by the ANC Study Group have shown that less than half of patients with breast cancer and non-Hodgkin's lymphoma received full doses of chemotherapy.
Researchers found that 21 per cent of those who were obese or severely obese received less than 85 per cent of the standard dose, compared to less than 10 per cent of those who were not overweight.
Gary Lyman, MD, MPH, principal investigator and director of the ANC Study Group said:
"Simply put, this evidence shows that doctors are likely to reduce the chemotherapy levels for these women, even though there is no solid medical basis to do it."
The study found that more than 32 per cent of women who did not finish high school had chemotherapy reduced, compared with 14 per cent of those with high school or college education. Researchers conclude that some doctors anticipate patients with less education will have difficulty tolerating chemotherapy and reduce the doses accordingly.
Researchers also found that chemotherapy dosage was more likely to be reduced for patients who lived in areas with higher levels of poverty and similarly suggest that doctors may be incorrectly anticipating the attitude of such patients towards treatment.
Jennifer Griggs, MD, MPH, lead author and associate professor of internal medicine at the University of Michigan Medical School said:
"We speculate that physicians have concerns about a patient's ability to tolerate the side effects of chemotherapy and that the physician's uncertainty about a patient's tolerance increases with increasing social distance. One might just as well ask why we are willing to give full doses to someone with more education. It may be that negotiating side effects and continued doses of treatment is easier when there is more shared culture."
The study recommends that women starting treatment for breast cancer should advocate for full doses by stressing their commitment to treatment.
Jennifer Griggs suggested:
"A patient might say to her physician that she is fully committed to her treatment, and in particular, to full doses of chemotherapy. I do not think it is the responsibility of the patient to ensure that she receives full weight-based doses, but physicians may be more comfortable dosing a patient fully when they are assured the patient is committed to her treatment."
Gary Lyman added:
"This whole issue of dose intensity is a major indicator of quality in cancer care and it must be addressed. We have new therapies and cures out there for many forms of cancer and sadly, sometimes we're not curing people because they are not getting the full doses that should be standard."