Breast cancer usually begins with the formation of a small well-defined tumor. Some tumors are benign, meaning that they do not invade other tissues, others are malignant, or cancerous. Malignant tumors have the potential to be metastases, which means to spread to other parts of the body. Once such a tumor reaches a certain size, is more likely that the radiate cells spread to other parts of the body through the bloodstream and lymphatic system. The different types of breast cancer can grow and spread at different rates. Some of them have years to spread beyond the breast, while others spread rapidly.

Breast cancer affects mostly women, but men can also develop the disease. A woman whose mother, sister, or daughter had breast cancer have a two to three times higher risk to get the disease, especially if in the family are affected by this disease at least two first-degree relatives.

Some studies have shown that breast cancer can increase colon cancer risk. There is also a genetic disorder, called Peutz-Jeghers syndrome which is known to increase a person's risk of both breast cancer and colon cancer. BRCA genes, the breast cancer genes, are the ones that increase a woman chances of breast cancer and colon cancer development. Although, both colon cancer and breast cancer can affect both men and women, a woman chances of getting breast cancer are higher and so her chances in developing both diseases too.

Both colon and breast cancer have some common risk factors. Drinking alcohol and the family heritage are only two of them. The usual every day diet can be another risk factor in getting both diseases.



However, the fact that a woman had breast cancer is considered a risk factor for colorectal cancer. But not all researches agree with this. A study about the risk of colon cancer after breast-cancer diagnosis in women with first incident breast cancer between the years 1974 and 1995 showed that women with previous breast cancer were 5% less likely to develop colon cancer and 13% less likely to develop rectal cancer than other women in general. The study also showed that the risk drop observed for colon cancer were most pronounced for women with breast cancer diagnosed after the age of 65 years old, in white women and in women with local stage breast cancer.  The study conclusion in that breast cancer does not increase automatically colon cancer risk.

Today, there are many women with both breast and colon cancer. Although the causes are not known, or researchers do not agree about the risk factors that lead to this fact and not all of them believe that there is a link between the two diseases development, if you had a colon or breast cancer case in you family, you should be careful at any sign that can lead you to the two diseases.