Higher Breast Density Linked to Increased Cancer Risk and Aggressive Tumors ► NCI Cancer Bulletin for August 9, 2011 - National Cancer Institute

NCI Cancer Bulletin for August 9, 2011 - National Cancer Institute: "Higher Breast Density Linked to Increased Cancer Risk and Aggressive Tumors

A study of postmenopausal women has confirmed that higher breast density is associated with a greater risk of breast cancer and revealed that the tumors that do develop are more likely to be aggressive. The findings were published online July 27 in the Journal of the National Cancer Institute.

Dense breast tissue, which has less fat and more glandular and connective tissue, is a known risk factor for breast cancer, and mammograms of dense breast tissue are often more difficult to read and interpret. But whether there are cancer subtypes specific to women with denser breast tissue is unclear.

Researchers from Harvard Medical School analyzed Nurses’ Health Study data from 1,042 women diagnosed with breast cancer between 1989 and 2004 and 1,794 matched healthy control subjects. The women with breast cancer had a higher average breast density than the women in the control group. Those with the highest breast density were more than three times more likely to develop cancer than those with the lowest breast density.

Breast density was associated most strongly with in situ, or noninvasive, tumors. Higher breast density was also associated with larger, higher-grade, and estrogen receptor (ER)-negative tumors, which tend to be more aggressive. The authors pointed out several study limitations. Most important, the findings may apply only to postmenopausal women.

In an accompanying editorial, Dr. Karla Kerlikowske of the University of California, San Francisco, and Dr. Amanda Phipps of the Fred Hutchinson Cancer Research Center suggested that a “masking effect,” in which dense tissue prevents the detection of smaller tumors by mammography, could be responsible for the observed association between dense breast tissue and larger, more aggressive tumors.

They also proposed that tumors may arise more often in dense breast tissue because of interactions with the larger number of epithelial and stromal cells present.

The results “suggest that breast density is an important risk factor for a range of biologically diverse subtypes of breast cancer, including tumors exhibiting characteristics indicative of poorer prognosis,” wrote the editorialists. “Given that the magnitude of the association with breast density is strong across all breast cancer subtypes and particularly for ER-negative disease, breast density should be included in risk prediction models across tumor subtypes,” they concluded.

Further reading: “Breast Density in Mammography and Cancer Risk” ► NCI Cancer Bulletin for October 21, 2008 - National Cancer Institute: "- Enviado mediante la barra Google"

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