Theoretically, breast cancer occurs due to the presence of malignant tumor tissue within the breast cells. Men also have breast tissue, so it can also lead to breast cancer. It is just that women are far more likely to develop breast cancer than men due to differences in their physiology. Although there are many similarities between male and female breast cancer, there are important differences between the two sexes. The biggest difference between the two is the size of the breast. Because men have much smaller breast tissue, they are more likely to notice when a small foreign body appears in their breast; but on the other hand, because men’s breast tissue is so small, it does not take long for a tumor to spread to the skin and muscle tissue of the breast. The rate of cancer cell spread is one of the most important factors affecting the treatment status after diagnosis. Because the lumps are small and difficult to detect for women with early stage breast cancer, the use of mammograms to examine them is very effective and common, yet it is rarely taken by men. In fact, mammograms can be effective for men as well, especially for men with a family history of the disease and those found to carry the BRCA2 variant gene (which is a sign of tumor appearance) in genetic testing.