Thinner girls may be at higher risk for postmenopausal breast cancer

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Thinner girls may be at higher risk for postmenopausal breast cancer,

according to the results of a Swedish population-based, case-control study

reported online in the April 15 issue of *Breast Cancer Research*.

" There is considerable evidence that childhood anthropometric measurements

are associated with postmenopausal breast cancer risk, " write Jingmei Li,

from Karolinska Institutet in Stockholm, Sweden, and colleagues. " It has

been consistently shown that variables that approximate body shape and size

early in life are inversely associated with breast cancer risk in

adulthood. "

The investigators studied the associations between childhood body size and

tumor characteristics among 2818 women with breast cancer and 3111 control

subjects. A 9-level somatotype allowed classification of childhood body

size, and fitting of unconditional logistic regression models allowed

estimation of relative risks. Using a case-only analysis, the investigators

obtained *P* values for heterogeneity by performing 1 degree-of-freedom

trend tests.

A large somatotype at age 7 years predicted decreased postmenopausal breast

cancer risk, even after adjustment for other strongly associated risk

factors such as age of menarche, adult body mass index, and mammographic

density. For large vs lean somatotype at age 7 years, odds ratio (OR) was

0.73 (95% confidence interval [CI], 0.58 - 0.91; *P* trend = .004).

Although this significant protective effect occurred within all subgroups

based on estrogen receptor (ER) and progesterone receptor (PR) status, the

effect was stronger for ER-negative tumors (OR, 0.40; 95% CI, 0.21 - 0.75; *

P* trend = .002) vs ER-positive tumors (OR, 0.80; 95% CI, 0.62 - 1.05;

*P*trend = 0.062;

*P* heterogeneity = .046). Somatotype at age 7 years was not associated with

tumor size, histologic characteristics, grade, or metastasis to lymph nodes.

" Greater body size at age 7 is associated with a decreased risk of

postmenopausal breast cancer, and the associated protective effect is

stronger for the ER-negative breast cancer subtype than for the ER-positive

subtype, " the study authors write. " ....Given the strength of the

associations, and the ease of retrieval of information on childhood

somatotypes retrospectively from pictures early in life, childhood body size

is potentially useful for building breast cancer risk or prognosis

prediction models. "

Limitations of this study include self-reported risk factor data and

possible recall bias.

" It appears counterintuitive that a large body size during childhood can

reduce breast cancer risk or alter one's prognosis, because a large birth

weight and a high adult BMI [body mass index] have been shown to otherwise

elevate breast cancer risk, " the study authors conclude. " There remain

unanswered questions on mechanisms driving this protective effect. Because

body size and related hormonal exposures are modifiable risk factors, women

might substantially decrease their risk of breast cancer, in particular the

more aggressive ER-negative disease, by monitoring their nutrition and

exogenous hormone intake at different points in life. "

*The National Institutes of Health; the Märit and Hans Rausing's Initiative

against Breast Cancer; and the W81XWH-05-1-0314 Innovator Award, US

Department of Defense Breast Cancer Research Program, Office of the

Congressionally Directed Medical Research Programs, supported this study.

The study authors have disclosed no relevant financial relationships.*

*Breast Cancer Res*. Published online April 15, 2010.

Abstract<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=PubMed & li\

st_uids=20398298 & dopt=Abstract>

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--

Ortiz, MS, RD

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