This Article  • Full text  • PDF  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citing articles on Web of Science (2)  • Contact me when this article is cited  Related Content  • Related articles  • Similar articles in JAMA  Topic Collections  • Oncology  • Breast Cancer  • Women's Health  • Women's Health, Other  • Alert me on articles by topic  Social Bookmarking   What's this?

	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

To the Editor: Dr Velicer and colleagues¹ estimated the relative risk of breast cancer by odds ratios derived from unconditional logistic regression models adjusted only for age and length of enrollment. Breast cancer risk and frequent use of antibiotics were both associated with higher education, being overweight, early menarche, positive family history, dense mammograms, menopausal status, and previous hormone treatment.

Although the authors considered several potential confounding factors, their use in stratified or multivariate risk adjustment was seriously compromised, with as many as two thirds of patients missing values on key variables. Furthermore, significantly more controls than cases appear to have had missing values for education, age at menarche, body mass index, family history, presence of high-density mammogram, and menopausal status. This systematic difference between cases and controls may introduce further bias into the analysis.

It is likely that, had the authors had complete data, one or more of these . . . [Full Text of this Article]

Gary H. Lyman, MD, MPH, FRCP(Edin)
gary_lyman@rmc.rochester.edu
Department of Medicine and Oncology

Eva Culakova, PhD; Jennifer Griggs, MD, MPH
Department of Medicine
University of Rochester Medical Center
Rochester, NY

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter     What's this?

RELATED ARTICLES

Use of Antibiotics and Risk of Cancer
, , , and
JAMA. ;291():2699-2699.
FULL TEXT  

Use of Antibiotics and Risk of Cancer

JAMA. ;291():2699-2699.
FULL TEXT  

Use of Antibiotics and Risk of Cancer--Reply
, , , and
JAMA. ;291():2700-2700.
FULL TEXT  

Antibiotic Use in Relation to the Risk of Breast Cancer
, , , , , and
JAMA. ;291():827-835.
FULL TEXT