From the Guidelines
Selective Serotonin Reuptake Inhibitors (SSRIs) should be used with caution in patients with a history of breast cancer, particularly those taking tamoxifen, due to potential interactions and decreased efficacy of tamoxifen.
Considerations for Using SSRIs in Breast Cancer Patients
- Tamoxifen interaction: SSRIs, such as paroxetine and fluoxetine, can inhibit the conversion of tamoxifen to its active metabolite, endoxifen, by blocking cytochrome P450 2D6 (CYP2D6) 1.
- Alternative SSRIs: Citalopram and venlafaxine may be better alternatives for breast cancer patients taking tamoxifen, as they have less impact on endoxifen concentration 1.
- Dosing and efficacy: Low-dose SSRIs, such as paroxetine 10-20 mg daily, can be effective in reducing hot flashes in breast cancer patients, but may have variable response and potential side effects 1.
- Monitoring and discontinuation: Patients should be monitored for side effects and discontinuation symptoms, and SSRIs should be tapered gradually to minimize withdrawal symptoms 1.
- Gabapentin as an alternative: Gabapentin may be considered as an alternative or additional treatment for hot flashes in breast cancer patients, particularly those who cannot take SSRIs or have sexual dysfunction 1.
From the Research
Considerations for Using SSRIs in Patients with a History of Breast Cancer
- The use of Selective Serotonin Reuptake Inhibitors (SSRIs) in patients with a history of breast cancer requires careful consideration due to potential interactions with tamoxifen and other hormone therapies 2, 3, 4.
- Some SSRIs, such as paroxetine, may inhibit the bioactivation of tamoxifen by cytochrome P450 2D6 (CYP2D6), potentially reducing its effectiveness in preventing breast cancer recurrence 4.
- However, other SSRIs, such as citalopram, may have limited potency to inhibit CYP2D6 activity and may be safer to use in combination with tamoxifen 2.
- Studies have shown that the concomitant use of SSRIs and tamoxifen does not necessarily increase the risk of breast cancer recurrence or mortality 2, 3.
- Nevertheless, some studies have found an association between SSRI use and increased breast cancer mortality, particularly with long-term use or heavy use of SSRIs 5, 6.
- The mechanisms underlying this association are unclear, but may involve confounding by indication, such as the presence of depression or other comorbidities 5.
- Clinicians should carefully weigh the potential benefits and risks of SSRI use in patients with a history of breast cancer and consider alternative treatments or closer monitoring of patients on concurrent SSRI and tamoxifen therapy 3, 4.
Key Factors to Consider
- The specific type of SSRI being used and its potential to inhibit CYP2D6 activity 2, 4.
- The duration and intensity of SSRI use, as well as the timing of use relative to breast cancer diagnosis and treatment 5, 6.
- The presence of comorbidities, such as depression or anxiety, and the potential impact of SSRI use on overall health and well-being 3, 5.
- The potential for interactions between SSRIs and other medications, including hormone therapies and other antidepressants 2, 3.