Serotonin signaling plays a role in regulation of autophagy in breast cancer cells

[Hopeful]

http://www.abstractsonline.com/Plan/ViewAbstract.aspx?sKey=54cb8dbf-f166-416b-907b-7b54ee7ddb68&cKey=11b45d22-3166-4934-a2a3-6adb82c3a58b&mKey=%7b507D311A-B6EC-436A-BD67-6D14ED39622C%7d

Hopeful

[norkdo]

so should I stop the anti-depressants?

[Jackie07]

Here's a newer article on the subject:

Prescrire Int. (http://www.ncbi.nlm.nih.gov/pubmed/21751753#) 2011 Jul-Aug;20(118):182-4.
Tamoxifen and CYP 2D6 inhibitors: caution.

[No authors listed]
Abstract

Tamoxifen, an oestrogen antagonist, is the standard hormone treatment for breast cancer. It is extensively transformed into its active metabolites by the cytochrome P450 enzyme system, especially into endoxifen by isoenzyme CYP 2D6. Co-administration of tamoxifen with isoenzyme CYP 2D6 inhibitors reduces this metabolism.

Selective serotonin reuptake inhibitor (SSRI) antidepressants inhibit isoenzyme CYP 2D6. Paroxetine and fluoxetine reduce the plasma concentration of endoxifen by about 50%. Two epidemiological studies involving about 3700 women have shown a link between the use of SSRI antidepressants and an increased frequency of breast cancer recurrence.

Other studies, with a lower level of evidence, were less convincing. Studies of other isoenzyme CYP 2D6 inhibitors showed no increase in the risk of breast cancer recurrence, but they lacked statistical power. It is better to avoid prescribing isoenzyme CYP 2D6 inhibitors to women treated with tamoxifen for breast cancer, especially SSRI antidepressants such as paroxetine and fluoxetine.

Depression does not always require antidepressant drug therapy, and antidepressants have no proven preventive impact on hot flushes linked to the menopause. If in certain cases, an antidepressant is considered necessary, it may be advisable to replace tamoxifen with anastrozole.

[Rich66]

The abstract Hopeful posted discusses serotonin and BC. It says "We found that serotonin slightly induced cell proliferation in estrogen receptor positive MCF-7 breast cancer cells. Because autophagy is implicated as a survival pathway in some cancers we also examined if serotonin induces autophagy in MCF7 ER+ breast cancer cells. We found that serotonin induces autophagy"

So..the suggestion seems to be that supplementation of serotonin (action of some antidepressant meds) levels might encourage ER+ breast cancer cell growth and survival.

The issue of whether drugs that are CYP 2D6 inhibitors (again, some anti depressants) interfere with Tamoxifen treatment is a separate issue...one that seems to ebb and flow based on pubmed searches.

So..seems like might be wise to only use antidepressants judiciously at this point.

On the other hand, there was some early research suggesting that Prozac might increase effects of chemo:
http://her2support.org/vbulletin/showthread.php?t=41742

The main researcher involved with that seems to have been pulled into different research.