Breast disease predisposing to cancer identified

Breast cancer is the most common cancer in women. Early puberty, late menopause, a family history of the disease, delaying childbirth or not having children are risk factors. Mastectomy is the surgical removal of the breast, usually to remove a malignant tumour. It involves removal of the whole breast (simple mastectomy) or a part of it depending on the extent of infection (segmental mastectomy). More often, in cases of cancer, the whole breast along with adjacent muscles is removed (radical mastectomy). It is best performed when the cancer is in its earliest stages.

Until now it was assumed that the chances of getting cancer were equal in both breasts in women suffering from atypical lobular hyperplasia (ALH) or abnormal cells, which supported arguments for a double mastectomy to prevent the disease. But scientists at the Vanderbilt University Medical Centre in Nashville, Tennessee found that although ALH tripled the risk of cancer, in most cases it developed in the breast as ALH.

The researchers studied 252 women who had undergone 261 benign surgical biopsies that showed ALH from 1950 to 1985 as part of the Nashville Breast Studies. Primary outcomes were development of invasive breast cancer and laterality of cancer compared with side of the biopsied breast. Fifty (20%) of 252 women treated by biopsy only developed invasive breast cancer. Relative risk of breast cancer in women with ALH was 3·1 but in 75 per cent of the women it was in the breast with the ALH.

The findings could have important implications for women with ALH. This suggests that they could have something certainly less than a mastectomy to reduce the risk. Scientists had thought that ALH, which is diagnosed in four to five percent of biopsies, was a precursor of cancer or a sign of something in the breast that favoured the development of the disease. But these findings suggest it is something in between because many, but not all, of the women with ALH in the study developed cancer in the same breast. Further studies are needed to determine the best methods of treating ALH to reduce the risk of cancer.