Saturday, January 20, 2007

Obese, Less Educated Women May Get Reduced Chemotherapy Dose

A study published in the Journal of Clinical Oncology suggests that breast cancer patients who are obese, have less income/education, or live in certain geographic regions are more likely to received a reduced (less than recommended) initial chemotherapy dose. The statistics are somewhat complicated, but here is a general summary of the study.

Citation: Griggs JJ, Culakova E, Sorbero ME, van Ryn M, Poniewierski MS, Wolff DA, Crawford J, Dale DC, Lyman GH. Effect of patient socioeconomic status and body mass index on the quality of breast cancer adjuvant chemotherapy. J Clin Oncol. 2007 Jan 20;25(3):277-84. [Abstract]

Who Was Included: >700 consecutive patients from multiple sites throughout the United States were included. To be eligible, they had to be >18 years old, have confirmed diagnosis of stages I, II, or III breast cancer, starting a new, standard chemotherapy regimen of at least 4 courses.

What Was Done: Information on the patients and treatment was collected through patient interviews and review of medical records. Expected dose of chemotherapy drugs was calculated using standard published doses considering the patient's body-surface area (using height and weight). For each drug, planned/expected dose was compared with the actual dose the patient received. An actual dose that was 85% or less of the expected dose was considered reduced.

What Information Was Collected: age, region (northeast, central, west coast, or south), other health problems, level of education, marital status, occupation, employment status, type of insurance, zip code, height, weight, tumor characteristics, planned and actual chemotherapy received, dates of treatment. Zip code data was used to determine median househould income, racial and ethnic composition, % of individuals and households below the poverty level, and % of individuals with high school or Bachelor's degree.

Findings: The authors found certain characteristics associated with getting a reduced chemotherapy dose. Patients who had a higher BMI (were heavy for their height) were more likely to get a reduced dose, as were patients in the South, patients living in areas with higher levels of poverty, and patients with less than a high school education. Patients who were severly obese were 4 times as likely to have a dose reduction compared to patients with a normal BMI. Patients in the southern region were 5.6 times more likely to have a reduced dose compared to those in the northeast. After adjusting for education level, lower median household income was no longer significant, but less education was associated with lower chemotherapy dose.

The authors speculate that while an obese patient's BMI may suggest a higher chemotherapy dose, doctors may be hesitant to provide the larger dose because of concerns about toxicity. They point to physician concerns/preconceptions (such as whether lower income/education patients will adhere to the treatment) as another factor which may be influencing dosing decisions.

The same researchers published a study in a 2005 issue of Archives of Internal medicine that reviewed patient records for obese patients and found first-cycle dose reductions (90% or less of standard published doses) in 9% of the healthy weight, 11% of the overweight, 20% of the obese, and 37% of the severely obese women.

  • University of Michigan Health System press release
  • MedlinePlus: Poorer, Less Education Women Get Less Chemo for Breast Cancer
  • American Cancer Society: Item from 2005 suggesting full dose of chemotherapy is safe for overweight breast cancer patients

    Technorati Tags: ; ; ; ;
    MeSH Tags: Breast Neoplasms; Chemotherapy, Adjuvant; Socioeconomic Factors
  • 3 Comments:

    Blogger BeckyJ said...

    I love your article summaries!

    Am wondering if they adjusted for other comorbidities in the analysis - e.g. if obese or lower income patients had other complicating health issues (malnutrition, anemia, cardiovascular disease) may modify the effect of weight on dose (e.g. increasing likelihood that dose adjustment will be required) - just further complicating the issue.

    10:27 PM  
    Blogger Rachel said...

    Thanks! The authors state that "age, cancer stage, comorbidity, hormone receptor status, and type of insurance were not significantly associated with use of reduced first cycle doses." It looks like more patients with 1 or more comorbidity did get a reduced dose, but not enough to be significant.

    10:07 AM  
    Blogger BeckyJ said...

    Interesting, thanks!

    It seems like they had a fairly decent sample size, but maybe not given the number of women in the US affected by breast cancer - would have strengthened their discussion of potential limitations if they had commented briefly on the size of their sample in comparison to the overall prevalence of disease (like a post-hoc power calculation)

    1:52 PM  

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