A new study has found that women with breast cancer have a 25 percent increased risk of developing a second cancer not necessarily related to their previous breast cancer.
The details of the study are published in the December 8, 2005 issue of the International Journal of Cancer, the official journal of the International Union Against Cancer (UICC). Researchers found that the high five-year survival rate, which is currently 77 percent, exposed these women to a greater risk of developing a second cancer. Previous studies have already shown that women with breast cancer risk developing second cancers in endometrium, ovary, thyroid, lung, soft tissue, blood, skin, stomach and colon. The risk was higher for younger women.
In the current study, the team of researchers led by Lene Mellemkj›fof the Danish Cancer Society in Copenhagen, Denmark tracked 525,527 patients with breast cancer during the period 1943 to 2000. Those analyzed were a part of cancer registries in Europe, Canada, Australia and Singapore. The researchers found that the risk of developing cancer increased by six times in the throat and the arms. This seems to suggest that the radiation therapy received by women make these areas vulnerable. "The excess of cancer after a breast cancer diagnosis is likely to be explained by treatment for breast cancer and by shared genetic or environmental risk factors although the general excess of cancer suggests that there may be additional explanations such as increased surveillance and general cancer susceptibility," the authors write. There was also an increased risk of developing myeloid leukemia or blood cancer, possibly as an effect of chemotherapy. "The overall impression from this very large study is that a breast cancer diagnosis has an effect on subsequent cancer risk in general, since so many cancer sites were seen to occur in excess of what was expected," the authors observed.
The International Journal of Cancer can be accessed at Wiley InterScience (http://www.interscience.wiley.com/