All organs in the body are made of cells. Individual cells are so small, they can be seen only through a microscope. Normally, cells divide in an orderly fashion to replace cells that have aged and died. Controls within each cell tell it to stop dividing if no new cells are needed. Occasionally, damage to DNA during cell duplication may cause the controls to malfunction. Cells begin to divide uncontrollably, forming lumps or tumors.



The word “tumor” comes from a Latin word that means “swelling.” A tumor could be composed of cells that divide excessively, but that do not invade or damage other parts of the body. A good example is a fibroid in the uterus, or a fibroadenoma in the breast. Both of these are called benign, that is, non-cancerous tumors.

Malignant tumors are composed of aggressively dividing cells that destroy surrounding tissues or travel to other parts of the body. In general conversation, the word “tumor” is often used to refer to a malignant condition, or cancer.


Growth Rate

Growth rate is the speed at which a lump or tumor grows. Different types of breast cancer grow at different rates. The time it takes for a tumor to become twice as large is called doubling time. The average doubling time for most breast cancer tumors is in the range of 50 to 200 days.The change of the first normal cell into a malignant cell happens years before any evidence of cancer can be detected by any tests that we have today. It may take three to five years for a cluster of cancerous cells to become large enough to be seen on a mammogram. In other words, by the time your cancer has been detected, it has been there for several years. That is why there is no harm in taking a few more weeks to decide on the best treatment possible.

Risk Factors

Who is more likely to get breast cancer? All women are at risk for developing breast cancer. It is the most common cancer in women, with over 200,000 new cases being diagnosed every year. Breast cancer also occurs in men, but rarely.


The main predisposing factor—called risk factor—for breast cancer is age. The older you are, the greater your chances of developing the disease. Four out of five breast cancers are found in women over the age of fifty. With a positive family history—having a first degree relative such as a mother, sister, or daughter who had breast cancer—a woman’s risk of developing breast cancer increases. So women with breast cancer should suggest to their close female relatives that they consult their physicians about their own risk factors, and begin an effective program of early detection. On the other hand, only about one in twenty cases of breast cancer is truly hereditary—that is, runs in the family—so not having a relative with breast cancer does not reduce the woman’s risk.

Some of the other risk factors have a connection to the female hormone estrogen. Interruptions in the levels of this hormone, such as occur during pregnancy and lactation, seem to have a protective effect. In other words, fewer menstrual periods lead to a lower risk. That is probably why women who had one or more children by the age of thirty are at a lower risk, while women who had an early menarche (first menstrual period) or a late menopause (last period) are at a higher risk.

Exercise and a low fat diet may have a protective effect, while alcohol intake of more than one drink per day may increase the risk.

While we don’t know exactly what causes breast cancer, we do know that it is not caused by a blow or a physical injury, and that it is definitely not contagious.

Breast Cancer Genes

Genes are specific areas on chromosomes (strands of genetic material contained in our cells) that program the cell with information for growth and function. Damage to specific genes on Chromosome 17 correlates with an increased incidence of hereditary-type breast cancer.

There are tests that can detect damage to the BRCA1 and BRCA2 genes. A “negative” gene test does not mean that the gene is normal. Rather, it indicates that a mutation has not been found. A negative test does not guarantee that the woman will not get breast cancer. Conversely, a “positive” test does not mean a woman will develop breast cancer, but it might open the door to a variety of problems if the woman’s insurance company or employer were to obtain this information.

The best advice for a woman with breast cancer is to suggest to her relatives that they consult a qualified risk counselor before undergoing any genetic testing