Play the Odds: Supplements and Chemo

http://www.abreastinthewest.ca/medical2.cfm?Num=43
Summer 2003 Vol.4 No.3

Play the Odds: Supplements and Chemo
Robin O?Brien BSc, BScPharm, PharmD, BCOP
Drug Information Specialist, BC Cancer Agency
Last December, a woman called to say thank you for suggesting she avoid
using supplements during her chemo. News that taking supplements could
counteract the benefit of breast cancer treatments was all over the front
page of the Vancouver Sun that morning. A few months before, she was
shopping for opinions after being urged to take a tote bag full of various
supplement pills along with her chemo. Now, she was finished treatment.
Supplement free.

I had to ask myself what made me so cautious about combining supplements
with chemo before there was a study to say one way or the other. What did
I know about chemo that gave me so much respect for the power of herbs and
supplements?

Chemo is like walking a tightrope. It?s a fine balance where too high a
dose is too toxic and too low a dose doesn?t work properly, so cancer
cells can escape. As well, while some cancers are exquisitely sensitive to
the effects of chemo and some are completely resistant, most are probably
in between and could be pushed in one direction or the other. Who knows
what herbs and supplements could do to this balance.

Most herbs haven?t even been tested with the notable exception of St.
John?s Wort. This popular herb is clinically proven to be helpful, and as
good as some prescription drugs, for mild to moderate depression, a common
problem for cancer patients. A cancer care team in Europe noticed that
people taking St. John?s Wort had fewer side effects than usual while
having chemo with a drug called irinotecan. No wonder - there was a drug
interaction. Chemo blood levels had dropped by half and it didn?t work
properly anymore. But that?s not all that St. John?s Wort can do.

St. John?s Wort can cause cells to sprout little drug pumps called PGP.
This is a worry because PGP can cause multi-drug resistance to chemo. As
fast as the chemo is transported into the cancer cell, PGP pumps it out
again. This is all part of the body?s natural protection against poisons,
which is especially important for plant-eating creatures like us. But the
net result can be resistance to chemo.

There is a lot of uncertainty about what happens when herbs and
supplements are combined with chemo. This makes the decision difficult.
Some women prefer to avoid herbs and supplements because they feel that
they have too much to lose or, if they are going to have chemo, they want
to be sure that they are getting the full benefit. Others, like those
who?ve already had a recurrence, may feel that they have little to lose.
They want to know how to integrate products with their chemo with minimal
risk.

Researching products carefully can improve the odds for success, as can
consulting with a cancer centre pharmacist and avoiding the following
types of products:

* products with a high risk of a negative interaction, for example,
antioxidants like vitamin C, vitamin E, beta-carotene, zinc, selenium,
coenzyme Q10 and melatonin.
* products that may act like fertilizers for breast cancer, for
example, products with hormonal activity like milk thistle and red clover
(found in Flor*Essence?).
* products that are supposed to slow tumour growth (chemo targets
rapidly dividing cells).
* herbal products since they may induce PGP.
* products with anticoagulant (blood thinning) activity since they may
increase bleeding risk when platelets are low, for example, the 4 G?s:
garlic, ginger, ginseng and ginkgo.
* products promoted to reduce treatment side effects since odds are
that the chemo won't work properly either.


Most importantly, it makes sense to hold hands with your cancer care team
when you are planning to use herbs and supplements during chemo. (The same
applies to surgery and radiation therapy.) Wait until at least the second
cycle of treatment so that you can see whether or not adding the products
makes any difference. And this way, your doctor can see how well you are
doing for at least the first cycle or two without anything else muddying
the picture. After all, it will be the chemo that is delayed or changed if
there is a problem, not the herbs and supplements.


The BC Cancer Agency handout "Natural Health Products and Cancer Therapy"
is available in the Unconventional Cancer Therapies Manual on the BC
Cancer Agency website (www.bccancer.bc.ca) or call the Canadian Cancer
Society Cancer Information Service 1.888.939.3333.

Natural Health Products and Cancer Therapy - New Recommendations

The BCCA Departments of Medical Oncology, Radiation Oncology, Surgical
Oncology, Pharmacy, Nursing and Nutrition are making a joint
recommendation for cancer patients to not use natural health products like
herbs and megadose vitamin and mineral supplements during surgery,
radiation and chemotherapy treatments. This recommendation comes after a
retrospective case-control study that found a trend for earlier recurrence
and shorter survival for breast cancer patients who were taking megadoses
of supplements during adjuvant therapy.

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