According to a new study by researchers at Yale University, many of the risk factors for more advanced breast cancer also apply to an early form of the disease known as breast carcinoma in-situ.

There are two types of breast carcinoma in-situ: lobular carcinoma in-situ (LCIS) and ductal carcinoma in-situ (DCIS). LCIS is rarely seen on a mammogram; it is usually discovered by a breast biopsy done to evaluate another suspicious area. LCIS is not cancer, but is considered a risk factor for the disease.

DCIS is a condition in which abnormal cells are found in the ducts of the breast. It is usually found by tiny specks of calcium, arranged in a particular pattern, on a mammogram. It is considered a pre-cancerous condition because these suspicious cells have not invaded the surrounding breast tissues. Over time, however, if left untreated, DCIS can become an invasive cancer.

Dr. Elizabeth Claus, the lead author of the study, noted that the number of women diagnosed with breast carcinoma in-situ has increased dramatically over the past decade due primarily to screening mammography. "Up to one in five women diagnosed with breast cancer has this form of the disease," she said.

Writing in the Journal of the National Cancer Institute, her team reported 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 the 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.

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.

SOURCES:
Yale University Medical Center (http://www.yale.edu)
Journal of the National Cancer Institute December 5, 2001; 93(23)1811-1817