Breast Cancer: Part 1

Doctors cannot always explain why one person gets cancer and another does not. However, scientists have studied general patterns of cancer in the population to learn what things around us and what things we do in our lives may increase our chance of developing cancer.

Anything that increases a person’s chance of developing a disease is called a risk factor; anything that decreases a person’s chance of developing a disease is called a protective factor. Some of the risk factors for cancer can be avoided, but many cannot. For example, although you can choose to quit smoking, you cannot choose which genes you have inherited from your parents. Both smoking and inheriting specific genes could be considered risk factors for certain kinds of cancer, but only smoking can be avoided. Prevention means avoiding the risk factors and increasing the protective factors that can be controlled, so that the chance of developing cancer decreases.

Although many risk factors can be avoided, it is important to keep in mind that avoiding risk factors does not guarantee that you will not get cancer. Also, most people with a particular risk factor for cancer do not actually get the disease. Some people are more sensitive than others are to factors that can cause cancer.
Talk to your doctor about methods of preventing cancer that might be effective for you.

The breast consists of lobes, lobules, and bulbs that are connected by ducts. The breast also contains blood and lymph vessels. These lymph vessels lead to structures that are called lymph nodes. Clusters of lymph nodes are found under the arm, above the collarbone, in the chest, and in other parts of the body. Together, the lymph vessels and lymph nodes make up the lymphatic system, which circulates a fluid called lymph throughout the body. Lymph contains cells that help fight infection and disease.

When breast cancer spreads outside the breast, cancer cells are most often found under the arm in the lymph nodes. In many cases, if the cancer has reached the lymph nodes, cancer cells may have also spread to other parts of the body via the lymphatic system or through the bloodstream.

Breast cancer is second only to lung cancer as the leading cause of cancer death among women in the United States. Breast cancer occurs in men also, but the number of new cases is small. Early detection and effective treatment is expected to reduce the number of women who die from breast cancer, and development of new methods of prevention continue to be studied.

To read more on this subject go to the National Cancer Institute website.

Breast cancer can sometimes be associated with known risk factors for the disease. Many risk factors can be changed but not all can be avoided. For example, women who inherit specific genes, such as BRCA1 or BRCA2, have a higher risk of developing breast cancer. High-risk genes are risk factors that cannot be changed. Researchers are looking for ways to prevent breast cancer in women with these genes.

The following factors are linked to an increased risk of breast cancer:


Estrogen, a hormone produced by the ovaries, appears to increase a woman’s risk for developing breast cancer. A woman’s exposure to estrogen and her risk of breast cancer is increased in the following ways:

  • The use of estrogen-progestin therapy, also called combination hormone replacement therapy (HRT).
  • Oral contraceptives (“the pill”).
  • Beginning to menstruate at age 11 or younger.
  • Beginning menopause at a later age.
  • Never being pregnant or having first child at an older age. Estrogen levels are lower during pregnancy and breast-feeding. A woman who has never had children, or who has her first child after the age of 35, has a higher risk of breast cancer than a woman who has her first child before the age of 20.


Exposure of the chest to radiation during x-rays and radiation treatment, especially at a young age, increases the risk of breast cancer beginning 10 years later. Although a small number of breast cancer cases can be linked to radiation treatment, certain groups of people may be more at risk. Women who received radiation therapy for childhood Hodgkin’s lymphoma, for example, are at a greater risk for breast cancer later in life.

Radiation therapy to treat cancer in one breast does not appear to increase the risk of developing cancer in the other breast.


Weight gain after menopause, especially after natural menopause and/or after age 60, is linked to increased breast cancer risk.


Drinking alcohol is linked to increased breast cancer risk. The more alcohol a woman drinks, the more the risk of breast cancer may increase, compared to a woman who drinks no alcohol.

SOURCE: National Cancer Institute of America

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