Mrsb / Shelagh:
The two factors central to the issue of potentially adverse effects of concurrent CAM interventions and oncotherapy are:
- Adverse interaction across the hepatic p450 Cytochrome enzyme system;
- Adverse exertion of anti-oxidant activity with concurrent chemotherapy.
As to the first, there is no issue: although letrozole (Femara) strongly inhibits CYP2D6, moderately inhibits CYP2C19, and has a low affinity for CYP3A4, the low affinity for CYP3A4 suggests minimal potential for adverse interactions across this enzyme, and in any case no component of the edge-CAM regimen exhibits a potentially adverse hepatic enzyme interaction, a rigorous inclusion criterion for any agent in the regimen, as I extensively document in my Drug Interactions in Oncology review (now 33+ pages).
And as to the second, it is irrelevant as it pertains to antioxidant-mediated chemotherapy (not all oncotherapy), and letrozole (Femara) exerts no significant antioxidant activity as part of its anti-estrogen endocrine capabilities.
Against a Blind Prohibition
And as I have already demonstrated there are numerous antioxidants widely deployed in oncology such as amifostine (Ethyol), used as a radio-protective and cytoprotective, mesna (Mesnex) a bladder-cytoprotective, dexrazoxane (Zinecard) a cardioprotective against oncotherapy cardiotoxicity, and pentoxifylline (Trental), a radioprotective used to treat RIF, radiation-induced fibrosis, all antioxidants, all without evidence of adverse interaction and FDA-approved as such, but they happen to be traditional medicine antioxidants as opposed to natural / CAM antioxidants, but if an injunction applies or not against one class then out of consistency it must apply to the other (see my Pleas for Consistency in my review).
However, despite there being no significant potential for adverse interaction as the above indicates, scheduling of administration, before, after or concurrent with oncotherapy is not stipulated by the regimen or my guidance associated with it: the decision is the patient's in consultation with her/his oncologist. As to my own perspective, I have discussed it here and at length in my above-cited oncology interactions review, and a blanket prohibition against concurrent CAM-oncotherapy is to date against the evidence, with numerous systematic reviews and meta-analyses failing to discover significant adverse potential despite widespread concerns expressed and disjunctions issued, against the data.
Not So Fast: The Need for Context-Dependent Assessment
But - and this is critical - although there is no plausible case for a broad disjunction against CAM-oncotherapy concurrency in general, this does not mean that each individual agent, whether CAM or traditional, does not in specific cases harbor a potentially adverse interaction. I cite and document the cases of interference with SJW (St. John's Wort) among many other CAM against (none of which however are part of the Edge-CAM regimen), as well as traditional medicine agents like statins among many others which can lead to problems of compromised efficacy or increased toxicity or both.
My approach is a context-dependent protocol. So for example I was recently consulted on a case of bupropion (Wellbutrin) being coadministered with tamoxifen, and I strongly caution against concurrent use. The oncologist saw no problem, thinking incorrectly the interactions problems with tamoxifen stemmed only from SSRI-type antidepressants, and furthermore the manufacturer itself denied any adverse potential. They were both mistaken, and demonstrably so, and were unaware of decisive evidence, which I presented to the contrary, and most disturbing Wellbutrin bears a clear FDA-required warning to the same effect which even the manufacturer seemed ignorant to, and the oncologist failed to uncover. But I would have no objection to tamoxifen and venlafaxine (Effexor) based on robust evidence. Thus my approach of context-dependent protocol views the broad claims of (1) that concurrent CAM-oncotherapy supplementation is to be avoided as problematic, and (2) that such supplementation is not problematic, as both invalid: instead, interaction safety is according to context, on a case by case basis depending on the agents used (this was how the component of my regimen were scrupiously vetted).
Breast Cancer Watch