Early Breast Cancer Shares Some Risk Factors with Advanced Breast Cancer, A Study by Yale Researchers Shows

Many of the risk factors for more advanced breast cancer also apply to an early form of breast cancer known as breast carcinoma in-situ, according to a study by Yale researchers that is the first large scale study of risk factors for this type of early cancer.

The number of women diagnosed with breast cancinoma in-situ has increased dramatically over the past decade due primarily to screening mammography, says Elizabeth Claus, M.D., associate professor in the Department of Epidemiology and Public Health and lead author of the study. “Up to one in five women diagnosed with breast cancer has this form of the disease,” she said.

Claus’ study, published in the December issue of the Journal of the National Cancer Institute, found that many of the risk factors for more advanced breast cancer were also risk factors for breast carcinoma in-situ, including a family history of breast cancer, a previous breast biopsy, fewer full-term pregnancies, and older age at menopause.

The researchers found no increased risk associated with use of either oral contraceptives or hormone replacement therapy, nor with alcohol consumption or smoking history.

The study also revealed that women who were diagnosed with breast carcinoma in situ were more likely than women without such lesions to have had a mammogram or annual clinical breast examination, but were no more likely to have performed breast self-examination.

“This study provides evidence that many of the risk factors for breast carcinoma in-situ are similar in nature and magnitude to those for invasive breast cancer, suggesting the possibility that some in-situ lesions may be a part of the pathway leading to invasive disease,” Claus said. “These data represent the largest examination to date of the epidemiology of breast carcinoma in-situ across all categories of age and all types of pathology. Studies such as these that examine early or potential precursor lesions are valuable in that they are conducted closer in time to risk factor exposure.”

The five-year study included about 1,000 Connecticut women between the ages of 20 and 79 years, all of whom were diagnosed with this early form of breast cancer. The study included a comparable number of women who did not have the disease.

Claus’ research group has received a $3 million grant from the National Cancer Institute to follow all of the women in the study for another five years. In this new study, the investigators will gather data on both medical and lifestyle outcomes for the 2,000 study participants. In addition, women diagnosed with breast carcinoma in situ will be offered testing for mutations in two breast cancer susceptibility genes, BRCA1 and BRCA2, along with genetic counseling. With these data, the researchers hope to learn why some women with early onset breast cancer develop more advanced breast cancer while other women do not.

The co-authors of the study were Meredith Stowe, associate research scientist, and Darryl Carter, professor of pathology, both at Yale School of Medicine.

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