contains tissue waste products and immune system cells that are on their way from areas of infection. Cancer cells can enter lymph vessels. Most lymphatic vessels of the breast lead to axillary (armpit) lymph nodes.
            
Lymph nodes are small bean-shaped collections of immune system cells that are important in fighting infections. When breast cancer cells reach the axillary lymph nodes, they can continue to grow, often causing swelling of the lymph nodes in the underarm area. If breast cancer cells have grown in the axillary lymph nodes, they are more likely to have spread to other organs of the body as well. This is why finding out whether breast cancer has spread to axillary lymph nodes is important in selecting the best mode of treatment.
  
Benign breast lumps
Most breast lumps are benign, that is, not cancerous. Most lumps are caused by fibrocystic changes. Cysts are fluid-filled sacs and fibrosis refers to connective tissue or scar tissue formation. Breast swelling and pain can be caused by fibrocystic changes. The breasts may feel nodular, or lumpy, and sometimes a clear or slightly cloudy nipple discharge is present. Benign breast tumors such as fibroadenomas or papillomas are abnormal growths, but they cannot spread outside of the breast to other organs. They are not life threatening.
 
Risk factors:
There are a number of factors, which increase the risk of having this cancer. Some of them are:  

• Age - Breast cancer is uncommon below the age of 35. The incidence sharply increases between the age of 35 and 50. It has also been noticed that cases sharply decrease at the time of menopause, though the cases have been noted to rise after the age of 65. Also the women who have had breast cancer before the age of 40, had three times the risk of developing a second breast cancer than those who developed the breast cancer after the age of 40.

• Family History - the risk is high in those with a positive family history of breast cancer, especially if the mother or sister developed breast cancer when premenopausal.

• Parity - an international case study done shows that breast cancer is directly related to the age at which the women bear their first child. An early first pregnancy seemed to have a protective effect. Those women who delayed their first pregnancy to their late thirties are at a higher risk than multiparous women.

• Hormonal factors - the association of breast cancer with early menarche and the late menopause suggests that ovary appears to play a crucial role in the development of breast cancer. Recent evidence suggests that both elevated oestrogen as well as progesterone, are important factors in increasing breast cancer risks.