Breast cancer patients taking the cancer drug, tamoxifen, are not at an increased risk of experiencing a recurrence of the disease if they are also taking antidepressants, a new study has found.

Tamoxifen is commonly prescribed to women with breast cancer to reduce their risk of suffering a recurrence of the disease. The drug is usually recommended for five years, however it can produce side-effects including sleep disturbance, hot flashes and depression. As a result, women on the drug may also be prescribed anti-depressants.

Previous research has suggested that antidepressants may reduce tamoxifen's effectiveness, so US scientists decided to investigate further.

They looked at almost 17,000 early-stage breast cancer survivors who had been treated with tamoxifen. Of these, over 8,000 were prescribed antidepressants. The participants were monitored for up to 14 years and took the breast cancer drug for an average of three years.

Almost 3,000 women overall - just over 17% - developed breast cancer again over the 14-year period, the majority of whom developed it in the same breast. However, the study found that the risk of recurrence was the same in women who had taken antidepressants and those who had not.

"We found no increased risk of recurrence, and this finding holds up regardless of the type of antidepressant used. This includes paroxetine (Seroxat), which had previously been reported to interfere with tamoxifen," the researchers from California commented.

They said that this study should help alleviate some concerns, especially as so many breast cancer survivors 'struggle with depression, sleep disturbance and other side-effects while on tamoxifen'.

"Our study should also help alleviate any concerns physicians have about prescribing antidepressants to their breast cancer patients to help improve their quality of life," they added.

Details of these findings are published in The Journal of the National Cancer Institute.