The most common types of breast cancers, the ductal and lobular carcinomas, develop from the terminal ductal-lobular units. In some tissues, cancers develop in a stepwise fashion. The tissue undergoes a series of changes which begins with atypical hyperplasia and progresses into carcinoma in situ and invasive carcinoma. Some hold the view that the breast carcinoma is the outcome of the same sequential changes that occurs within the ductal-lobular units of breast tissue. In fact, genetic abnormalities have been reported in pre-malignant and malignant breast epithelium suggesting that the development of breast cancer may be dependent on these genetic abnormalities. Deng et al, in the December 20, issue of Science describe loss of heterozygosity in the morphologically normal tissues that reside adjacent to the breast carcinomas. The most common abnormality was found at chromosome 3p22-25. From ten cases of breast carcinomas that displayed the loss of heterozygosity, this abnormality was seen in normal tissues adjacent to the breast carcinoma in six cases. The loss of heterozygosity at 17p13.1 and at 11p15.5 which were seen, respectively in sixteen and five breast cancers, was markedly lower in the normal tissues. Only one normal tissue in each series showed this abnormality. These abnormalities may define localized areas within the breast tissue and adjacent to the breast carcinoma that are predisposed to the development of breast cancer. Thus, detection of these abnormalities in the breast tissue may be clinically useful. In addition, traditionally, after lumpectomies or mastectomies, pathologists make certain that the breast cancers are removed in their entirety and with a rim of normal tissue. If additional studies confirm the clinical importance of the findings reported by Deng et al, then, it may become necessary to remove the normal appearing tissues that exhibit the genetic abnormality.

FIGURE LEGEND:

Top figure: The dense area within the mammogram is a breast carcinoma. The second figure shows the gross appearance of the breast carcinoma. Breast carcinoma appears as a white, stellate tumor which is hard to palpation. The third micrograph shows the light microscopic appearance of the normal appearing breast tissue. The figure at the bottom shows the light microscopic appearance of the duct cell carcinoma of the breast. A cluster of tumor cells reside within the vascular/lymphatic channels.

REFERENCE:

Deng G, Lu Y, Zlotnikov G, Thor AD, Smith HS: Loss of heterozygosity in normal tissue adjacent to breast carcinomas. Science 274, 2057-2059

RESOURCES:

Fast Facts About Breast Cancer
The Breast Cancer Compendium
Breast Cancer Awareness Crusade
Breast Cancer Overview
Breast cancer detection
Breast Cancer Answers
Breast net; NSW Breast Cancer Institute, Australia
American Cancer Society
OncoLink
NHMRC; National Breast Cancer Centre
Y-me
Breast Care On Line
Breast Health and Breast Cancer Network

DATABASE LINKS:

BRCA1: Gene Map Locus: 17q21

BRCA2: Gene Map Locus: 13q12.3