Herb-Drug Interactions in Oncology: Focus on Mechanisms of Induction

[heblaj01]

http://theoncologist.alphamedpress.org/cgi/reprint/11/7/742
Herb-Drug Interactions in Oncology: Focus on Mechanisms of Induction
(This information is current as of December 2, 2006)

This a detailed & highly technical description of the interactions (often negative) between some supplements or foods (such as grapefruit) & chemo drugs.
It deals with the roles of nuclear receptors, such as the pregnane X receptor(XPR), the constitutive androstane receptor,and the vitamin D-binding receptor as well as with that of the metabolizing enzyme CYP3A4 (part of the P450 family).

Two tables are of particular interest:
Table 1:
Metabolizing enzymes involved in the metabolism of chemotherapeutic drugs [15, 85–87]

Table 3:
Potential of complementary and alternative medicines (CAM) to activate nuclear receptors and to induce metabolizing enzymes
(List of selected supplements & foods & whether or not they may interact with chemo)

[Lolly]

Yes, pretty technical, but I grasped enough to reaffirm my belief that while on chemo, it's best to discuss any supplements with one's onc. I was first made aware of the possible negative interactions of CAM's with anti-cancer therapy when starting radiation back in 2000. My rad onc told me that "although no hard data was available" there was enough anecdotal evidence emerging that he was advising his patients to forgo CAM's while in radiation treatment. I was somewhat shocked, as I had taken various CAM's throughout my chemotherapy for primary disease, and had no idea they might have been inhibiting the effects of the chemo. I thought they would have an additive effect! Since then, I've taken care to inform my onc of anything I'm taking in between treatments, and while on chemo I generally stop taking anything else, unless I've discusse such use with my onc and gotten the ok.

<3 Lolly

[heblaj01]

Lolly,
I think you got the right attitude of caution when deciding to use CAM concurrently with conventional treatments.
The complex data in the article I posted is mostly from laboratory experiments on cells. It may even be more complicated or different in humans if I understand correctly, for instance, the activity of supplements such as the various forms of vitamin E depending on if one looks at what happens in the guts or in the liver: see
http://dmd.aspetjournals.org/cgi/reprint/32/10/1075.pdf
This is reference #62 in the article & it deals in great detail with Vitamin E

[smhowell]

You've got to be kidding...CAM, nutritional suppliments, prayer and Herceptin are the only things that have kept me alive and still active past my expiration date. Unfortunately, here in Oklahoma, no oncologist (I'm still searching) knows anything about alternative medicine; it just upsets them and appears to make them more anxious to kill you off with toxic traditional therapies if you try to discuss it with them. You guys above must come from more progressive areas of the country, or maybe your cancer isn't as aggressive as mine.

[heblaj01]

smhowell,
My comment on CAM was not to imply an across the board attitude of discarding its use. But based on the complexe chemical nature of some supplements (especially those not refined to a single compound) & the lack of thorough scientific data on possible interactions , it is prudent to be careful & seek as much info as possible before starting on a specific CAM treatment.
This prudence is even more of the order if CAM is applied concurrently with conventional cancer treatment.

[Lolly]

smhowell, keep searching for that open-minded oncologist; they're worth their weight in gold. I'm fortunate that mine is, as you say, progressive. BUT, he's very cautious about the use of CAM's DURING chemotherapy. I think they're strong medicine and I wouldn't start "mixing and matching" my conventional medications without checking with my doc, and feel the same way about most of my CAM's now. When I'm in between chemo's and just receiving maintenance Herceptin, I feel free to take all manner of supplements and have my doc's blessing.
Good luck in your search for an oncologist who listens to your concerns and beliefs. I was just lucky to get one on the first go round.

<3 Lolly

[tousled1]

Smhowell,

I truly am sorry that you did not/can not find an oncologist who you feel is progressive. I'm like Lolly, very happy with my oncologist who is also very progressive. I too agree that mixing CAMs with traditional chemotherapy should not be done without consulting with your oncologist first. As for not having a breast cancer that is as agressive as yours, I can only say that all HER2+ breast cancer is extremely agressive. You didn't mention when you were diagnosed or what your hormone or HER2 status was.