Long-term tamoxifen use may up aggressive breast cancer risk

Washington, Aug 26 (ANI): Tamoxifen drug, commonly used for treating breast cancer, can actually increase the severity of the disease, finds a new study.

The researchers showed that long-term tamoxifen use increases risk of an aggressive, hard to treat type of second breast cancer.

Lead researcher Dr Christopher Li at Fred Hutchinson Cancer Research Centre compared the breast-cancer patients who received the estrogen-blocking drug tamoxifen to those who did not and found that while the drug was associated with a 60 percent reduction in estrogen receptor-positive, or ER positive, second breast cancer - the more common type, which is responsive to estrogen-blocking therapy - it also appeared to increase the risk of ER negative second cancer by 440 percent.

"This is of concern, given the poorer prognosis of ER-negative tumors, which are also more difficult to treat," said Li.

The findings from the new study supports Li's earlier research suggesting a link between long-term tamoxifen use and an increased risk of ER-negative second cancers.

"The earlier study had a number of limitations. For example, we did not have information on the duration of tamoxifen therapy the women received," said Li.

"The current study is larger, is based on much more detailed data, and is the first study specifically designed to determine whether tamoxifen use among breast cancer survivors influences their risk of different types of second breast cancers," the expert added.

However, Li insists that while the study confirmed a strong association between long-term tamoxifen therapy and an increased risk of ER-negative second cancer, it does not suggest that breast cancer survivors should stop taking hormone therapy to prevent a second cancer.

The findings are published in the journal Cancer Research. (ANI)