Risk of second cancer following breast cancer

Reported by Susan Aldridge, PhD, medical journalist

A large study shows that women who have breast cancer run a 25 per cent increased risk of getting a second cancer elsewhere.
The five year survival rate for breast cancer is about 77 per cent, but long-term there is a risk of developing a second cancer. That is the conclusion of a survey covering over half a million breast cancer patients carried out by the Danish Cancer Society. The cases were drawn from Europe, Canada, Australia and Singapore.

Records from 1943 to 2000 were analyzed and over 133,000 of the women were followed for more than ten years after their initial diagnosis of breast cancer. An increased risk of cancer was found in many different sites, as has been seen in other research. It may be that treatment for the breast cancer leads to the second cancer. There may also be shared genetic or environmental factors that increase the risk of both cancers.

The study found a six times average increased risk of cancer in the connective tissue of the thorax and upper limbs - suggestive of a link with radiotherapy. There is also an increased risk of endometrial cancer which cannot entirely be attributed to tamoxifen use because it was found in cases diagnosed before the drug was in use. Obesity seems to be a common link between breast cancer and increased risk of colon cancer and kidney cancer at a later stage. There is also an increased risk of ovarian cancer, which starts within a year of breast cancer diagnosis. The study highlights the need for careful monitoring of the health of women after a breast cancer diagnosis, even if they have recovered.

Source
International Journal of Cancer online 8th December 2005