Digoxin, which is used to treat heart failure and arrhythmias, has estrogen-like effects. It has been shown to increase the risk of breast cancer in women and men. However, laboratory studies have also shown that digoxin has anticancer effects, but the mechanism of action is unclear. Now, a new article suggests that digoxin has a cancer-promoting effect in women. Digoxin has estrogen-like effects Digoxin is derived from the digitalis plant. Digoxin is chemically similar to estrogen and appears to have estrogen-like effects. For example, it can cause breast enlargement in men and has also been shown to have less prostate cancer in men, which is consistent with estrogenic effects. Digoxin increases the risk of breast cancer in women and men Several studies in Northern Europe have demonstrated that digoxin use increases the risk of breast cancer in women. For example, a Danish study in 2111 that included 104,648 women showed that women who were currently using digoxin had 1.4 times the risk of breast cancer than those who were not using digoxin. However, women who had previously used digoxin did not have an increased risk of breast cancer. And the risk of breast cancer was higher in hormone receptor-positive patients than in hormone receptor-negative patients. In the same study, digoxin also increased the incidence of uterine cancer (endometrial cancer and uterine sarcoma). One study showed that Nordic men taking digoxin had twice the risk of breast cancer as those not using digoxin. The correlation between digoxin and the risk of breast cancer is similar to the correlation between obesity and the risk of breast cancer, which is a known risk factor for the development of breast cancer in men. Laboratory studies suggest that digoxin has anticancer effects Laboratory studies have found that digoxin has anticancer activity, but the mechanism of action is unclear. Digoxin has been shown to inhibit the growth of primary tumor cells and the metastasis of tumor cells to the lungs in a mouse model of breast cancer. However, it is unknown whether the anti-cancer effects of digoxin observed in mice will also occur in humans. Some experiments have shown that digoxin increases apoptosis (programmed cell death) in triple-negative breast cancer cells. Another study reported suggests that paclitaxel in combination with digoxin may be more effective than paclitaxel alone in the treatment of breast cancer. These experimental results may trigger the creation of more effective anti-cancer drugs in the future. However, in the meantime, demographic studies have shown that digoxin increases the risk of breast development, so digoxin may be unsafe for breast cancer survivors and those at high risk for breast cancer.