Certain statistical factors regarding breast carcinoma have been fairly well established. It is the most common primary carcinoma occurring in the female and accounts for about 22 per cent of all malignant tumors in women. Based upon the present population, there are more than 60,000 new cases of breast cancer in women each year in the United States. Shimkin of the National Cancer Institute states that in 1 of every 18 women (5.5 per cent) breast cancer will develop during the anticipated life expectancy of 72 years.The incidence of cancer is higher in almost every organ and tissue of the body in the male as compared to the female, except in the breast, the genital organs and to a much lesser extent, the large intestine, biliary passages and thyroid. Breast cancer accounts for only 0.2 per cent of primary malignant neoplasms in the male and there are only about 600 new cases each year in the United States.Breast cancer accounts for 19 per cent of all cancer deaths in women and for 0.2 per cent in males. Each year in the United States more than 30,000 women die from breast cancer, compared to 300 men. This tumor accounts for 3 of every 1, OOO male cancer deaths.In contrast to cancer of the genital organs, cancer of the breast is more frequent in the white than in the non-white population. Although the incidence is very low among males, the same relationship with regard to race holds true for each sex. The average incidence rates are 0.8 for white, and 0.2 for non-white males versus 72.6 for white, and 53.9 for non-white females per 100,000 population. Breast cancer accounts for about 1 cancer death in 5 among white women and 1 in 6 among non-white women. OTHER FACTORS RELATED TO INCIDENCECancer is more likely to develop in the left than in the right breast, aa shown by Busk and Clemmesen's survey of 4,139 cases of female breast cancer from the Danish Cancer Registry. They found 111 cases of left breast cancer for every 100 cases of right breast cancer. Harnett found the same ratio for left to