Benign (non-cancerous) breast lumps can be grouped into two main types:

• fluid filled lumps (called cysts)
• solid lumps

There is no evidence that breast cysts are forerunners of breast cancer but women who develop multiple cysts are at slightly increased risk of developing breast cancer. However this risk is too low for there to be any need for additional breast screening. It is important that women who have had several cysts drained don't ignore new lumps but always get them checked by a doctor to make sure they are cysts.

With solid benign breast tumours the situation is a bit more complicated. These growths can be grouped into three types depending on their appearance under the microscope.

• Non-proliferative breast tumours - the most common type (about 7 out of 10 solid benign breast lumps). These are made up of normal looking cells that are growing at a normal rate.  There is no evidence that non-proliferative breast lumps increase the risk of cancer.

• Proliferative breast tumours - (about 1 in 4 solid benign breast lumps)  In these lumps the cells look normal but are growing and making new cells more quickly than usual.  If one or more of these is found then there is an increased risk of breast cancer developing. A woman is about twice as likely to develop a breast cancer sometime during the next 20 years as a woman of the same age who has not developed this type of lump.

• Proliferative breast tumours with atypical features (about 1 in 20 solid benign breast lumps). The cells have started to look different from normal (atypical) and are growing and making new cells more rapidly than usual.  If one or more of these lumps is found then there is an increased risk of breast cancer developing. Overall a woman with this is about 4 to 5 times as likely to develop a breast cancer sometime during the next 20 years as a woman of the same age who has not developed this type of tumour. This risk is further increased for those women who have a strong family history of breast cancer.

Any solid benign breast lump that is removed will always be examined under the microscope. If this examination shows changes which suggest there is an increased risk of cancer developing in the future then the doctors will usually discuss ways of reducing that risk.