Study Indicates Antidepressant Use Safe for Stress in Breast Cancer

Researchers confirm antidepressants do not cause recurrence in breast cancer patients treated with tamoxifen.

An exhaustive study by Kaiser Permanente has confirmed the safety of antidepressants in breast cancer patients treated with tamoxifen. Published in the Journal of the National Cancer Institute, the study negated previous suggestions of an increased risk of recurrence with concomitant use of tamoxifen and anti-depressants in breast cancer patients.

Tamoxifen is frequently recommended as standard adjuvant treatment in women with breast cancer to reduce their risk of recurrence.

The drug has been shown to reduce cancer recurrence by 50% and breast cancer mortality by over 30% in women with early-stage estrogen-receptor positive disease. However, tamoxifen has side effects that include hot flashes, night sweats, and depression, and when women took antidepressants that included paroxetine, fluoxetine, and bupropion, research suggested they interfered with the mechanism of tamoxifen that prevents recurrence.

With the new study, this belief has been alleviated. The retrospective study evaluated electronic health records of 16,887 breast cancer survivors (stages 0 to 2) diagnosed between 1996 and 2007, who were treated with tamoxifen. With follow-up till the end of 2009, the percentage of days of overlap of tamoxifen and an antidepressant (paroxetine, fluoxetine, other selective serotonin reuptake inhibitors, tricyclics, and other classes) were considered.

“We found no increased risk of recurrence, and this finding holds up regardless of the type of antidepressant used. This includes paroxetine, which had previously been reported to interfere with tamoxifen,” confirmed lead author Reina Haque, PhD, MPH.

What the study found was while nearly 50% (8099) of the study population used antidepressants, 2946 of them develop subsequent breast cancer during the 14-year follow-up. There was no significant increase in recurrence when paroxetine was administered while patients were on tamoxifen.

The authors reported a decrease in hazard ratio with increase in overlap days between the 2 treatments, although it was not statistically significant.

For 25%, 50%, and 75% increases in percent overlap days between paroxetine and tamoxifen, hazard ratios (HR) were 1.06 (95% confidence interval (CI), 0.98 to 1.14; P = .09), 1.13 (95% CI, 0.98 to 1.30; P = .09), and 1.20 (95% CI, 0.97 to 1.49; P = .09), respectively, in the first year of tamoxifen treatment. HR decreased to 0.94 (95% CI, 0.81 to 1.10; P = .46), 0.89 (95% CI, 0.66 to 1.20; P = .46), and 0.85 (95% CI, 0.54 to 1.32; P = .46) by the fifth year.

Results followed a similar trend for the other antidepressants, the authors write.

“Given that thousands of breast-cancer survivors struggle with depression, sleep disturbance, and other side effects while on tamoxifen, our study should help alleviate any concerns physicians have about prescribing antidepressants to their breast-cancer patients to help improve their quality of life,” Haque said.