| · Medical regulation
· PSNC
· Drug interactions
· Nutraceuticals
· Community pharmacy
Letters to the Editor
|
Nutraceuticals
Use of nutraceuticals in cancer
From Dr M. de Lemos, MRPharmS
Hill et al have provided an extensive review of nutraceuticals that may
have some anti-cancer
activities (PJ, 2 September, pp277–84). From
my experience of advising cancer patients on natural health products, there
are several points I would like to emphasise.
First, prevention and treatment of cancer are two different things. A substance
that may help to prevent cancer is not necessarily useful for the treatment
of the disease, and vice versa. For example, oestrogen alone can promote
the continuing growth of oestrogen-receptor positive breast cancer. Hence
anti-oestrogen therapy like tamoxifen may arrest the progress of this disease.
However, oestrogen alone is not sufficient to cause de novo development
of breast cancer, otherwise many more women would have developed breast
cancer.
Second, a randomised, controlled trial has shown that 25g of flaxseed in
muffins may reduce the proliferation of breast tumour cell growth in women
with breast cancer.1 Another issue with flaxseed is that, like other phytoestrogens,
one needs to consider the implication of its oestrogenic effect on women
with breast cancer, particularly if it is oestrogen-receptor positive.
For example, can it interfere with the efficacy of antioestrogen therapy
like tamoxifen? Animal studies do not seem to suggest that.2,3 However,
given that the oestrogenic lignans need to be converted by the gut bacteria,
one needs to be careful in extrapolating rodent studies to humans, each
with their own microflora. Interestingly, flaxseed oil has been shown to
increase breast tumour growth in transgenic mice at certain doses.4
Finally, Lissoni et al produced nearly all the randomised studies on melatonin
versus observation in cancer patients5–12 and few have duplicated
their findings.13 There are several limitations to their studies. It is
unclear if assessment was blinded, which may be important when the endpoints
included reduction in toxicity. It is unclear if some patients were included
in more than one report,5,6,10 as few details on the patients and cross-references
with previous studies were provided. Also missing were details on the methods
of randomisation, prognostic factors, chemotherapy regimens, etc.7,10 In
some cases, the survival data presented were unclear. For the advanced
disease study, less than 50 per cent of the events had occurred at one
year. Hence, the apparent increase in survival may be premature.7 In contrast,
the survival curves for the lung cancer study were presented as five-year
ones, although most patients already died within the first year.10
Mário de Lemos
Vancouver, Canada
References
1. Thompson LU, Chen JM, Li T, et al. Dietary flaxseed alters tumor biological
markers in postmenopausal breast cancer. Clinical Cancer Research 2005;11:3828–35.
2. Chen J, Hui E, Ip T, et al. Dietary flaxseed enhances the inhibitory
effect of tamoxifen on the growth of estrogen-dependent human breast cancer
(mcf-7) in nude mice. Clinical Cancer Research 2004;10:7703–11.
3. Chen JM, Mann J, Thompson LU. Dietary flaxseed dose dependently enhances
the inhibitory effect of tamoxifen on the growth of human breast cancer
(MCF-7) xenografts in nude mice. FASEB Journal 2005;19(Part 2 Suppl S):A993
(abstract 583.6).
4. Rao GN, Ney E, Herbert RA. Effect of melatonin and linolenic acid on
mammary cancer in transgenic mice with c-neu breast cancer oncogene. Breast
Cancer Research and Treatment 2000;64:287–96.
5. Lissoni P, Paolorossi F, Ardizzoia A, et al. A randomized study of chemotherapy
with cisplatin plus etoposide versus chemoendocrine therapy with cisplatin,
etoposide and the pineal hormone melatonin as a first-line treatment of
advanced non-small cell lung cancer patients in a poor clinical state.
Journal of Pineal Research 1997;23:15–19.
6. Lissoni P, Barni S, Ardizzoia A, et al. Randomized study with the pineal
hormone melatonin versus supportive care alone in advanced nonsmall cell
lung cancer resistant to a first-line chemotherapy containing cisplatin.
Oncology 1992;49:336–9.
7. Lissoni P. Is there a role for melatonin in supportive care? Support
Care Cancer 2002;10:110–16.
8. Lissoni P, Barni S, Mandala M, et al. Decreased toxicity and increased
efficacy of cancer chemotherapy using the pineal hormone melatonin in metastatic
solid tumour patients with poor clinical status. European Journal of Cancer
1999;35:1688–92.
9. Lissoni P, Tancini G, Barni S, et al. Treatment of cancer chemotherapy-induced
toxicity with the pineal hormone melatonin. Support Care Cancer 1997;5:126–9.
10.Lissoni P, Chilelli M, Villa S, et al. Five years survival in metastatic
non-small cell lung cancer patients treated with chemotherapy alone or
chemotherapy and melatonin: a randomized trial. Journal of Pineal Research
2003;35:12–15.
11.Lissoni P, Meregalli S, Nosetto L, et al. Increased survival time in
brain glioblastomas by a radioneuroendocrine strategy with radiotherapy
plus melatonin compared to radiotherapy alone. Oncology 1996;53:43–6.
12.Lissoni P, Barni S, Ardizzoia A, et al. A randomized study with the
pineal hormone melatonin versus supportive care alone in patients with
brain metastases due to solid neoplasms. Cancer 1994;73:699–701.
13.Cerea G, Vaghi M, Ardizzoia A, et al. Biomodulation of cancer chemotherapy
for metastatic colorectal cancer: a randomized study of weekly low-dose
irinotecan alone versus irinotecan plus the oncostatic pineal hormone melatonin
in metastatic colorectal cancer patients progressing on 5-fluorouracil-containing
combinations. Anticancer Research 2003;23(2C):1951–4. |
The
Pharmaceutical Journal