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Cancer: Should Patients Take Dietary Supplements?
Updated: 06/30/2004
There continues to be controversy as to whether cancer patients should
take certain vitamin and mineral supplements. Some in mainstream medicine
have attacked the use of vitamin supplements as being potentially harmful,
despite published scientific evidence indicating that cancer patients
who supplement benefit. The criticism about cancer patients taking supplements
is not limited to conventional oncologists. There have also been debates
among Life Extension advisors as to what supplements are best for cancer
patients to take.
Unlike heart disease, cancer is a very complicated disorder. No one has
definitively shown what supplements a cancer patient should take nor at
what stage in the disease process the supplements should be initiated.
It could be that some dietary supplements are of benefit at some phases
of cancer treatment (such as enhancing immune function), but detrimental
in others (such as protecting cancer cells against the effects of certain
chemotherapy drugs).
Most people familiar with published scientific literature are surprised
that there is any argument over the value of dietary supplements and cancer
treatment. The problem is the complexity of cancer compared to other diseases.
For instance, there is a scientific consensus that folic acid is beneficial
in cardiovascular disease patients because it lowers homocysteine and
protects the arterial system via other mechanisms; no one argues against
this. There is also substantial evidence that folic acid dramatically
lowers the risk of many forms of cancer; few scientists disagree with
this premise either. However, the role of high-dose folic acid in the
treatment of cancer is not as clear-cut. Every human and animal cancer
study indicates that folic acid improves survival, yet those familiar
with the molecular actions of folic acid are concerned that very high
amounts could potentially facilitate cancer cell propagation.
In the following section, we review all studies involving the use of
dietary supplements by human cancer patients. We also discuss reasons
why some scientists believe that cancer patients should approach supplementation
with a degree of caution.
The reader should know that no organization has ever methodically analyzed
the scientific literature to address the complex issue of using dietary
supplements in the treatment of cancer. Although articles have been written
about isolated effects of certain nutrients, there has not been an attempt
to consolidate this knowledge in a way that provides practical guidance
for the cancer patient.
Human Research on Cancer and Dietary Supplements
Although there are hundreds of published studies showing that the ingestion
of certain nutrients may reduce cancer risk, relatively few investigate
the effects of dietary supplement intake by those already stricken with
cancer. This paucity of data has enabled mainstream oncologists to speculate
that certain dietary supplements might protect cancer cells from apoptosis
(programmed cell death). The assertion made by some oncologists is that
there may be a risk when cancer patients take certain dietary supplements.
To get the bottom-line facts on what happens to cancer patients who take
dietary supplements, a MEDLINE search was conducted using key words to
access all peer-reviewed published studies relating to groups of cancer
patients who used various dietary supplements. The criteria for the studies
selected was that the dietary supplement had to show an effect on the
clinical outcome of the patient--preferably relating to long-term survival--as
opposed to therapies that offer a short-term benefit, such as mitigating
chemotherapy toxicity. Oncologists generally acknowledge that supplements
can mitigate chemotherapy and radiation therapy side effects. The question
is whether cancer patients taking supplements are actually surviving longer.
Below is a synopsis of the MEDLINE findings:
- A study was conducted on non-small cell lung cancer patients over
age 60 that had already had the primary tumor(s) surgically removed.
The prognosis for this type of cancer is grim. The doctors compared
vitamin users to nonusers and measured blood folate as an indicator
of folic acid intake. The median survival for the nonusers was only
11 months compared to an astounding 41 months for the vitamin users.
Supplement users, in other words, survived almost four times longer
than nonusers. In those patients with higher blood levels of folate,
there was a 68% improvement in survival. Because the doctors adjusted
for other mortality factors, the findings of this study suggest that
cancer patients should take vitamin supplements (Jatoi et al. 1998).
- A more specific study looked at a group of transitional cell bladder
cancer patients. One group was given BCG (tuberculosis vaccine) immune-augmentation
therapy plus the recommended daily allowance (RDA) of vitamins. The
second BCG-treated group received the RDA plus 40,000 IU of vitamin
A, 2000 mg of vitamin C, 400 IU of vitamin E, 100 mg of vitamin B6,
and 90 mg of zinc. After 5 years, the tumor recurrence rates were 91%
in the group receiving the low-potency RDA vitamins, but only 41% in
the mega dose vitamin group. In this study, large doses of vitamins
resulted in a 55% reduction in tumor recurrence (Lamm et al. 1994).
- Malignant melanoma is virtually impossible to stop once it has spread
beyond the primary lesion. A rare form of melanoma occurs in the iris
of the eye, and it is considered high risk because it is often found
too late. Nine random high-risk patients with T3 melanoma of the eye
first underwent standard conventional therapy to eradicate the primary
tumor. These patients were then put on a supplement regimen consisting
of folic acid, trace minerals, amino acids, and fatty acids. After 80
months of follow-up, none of these nine patients experienced recurrent
disease, which was significantly better than a similar group of high-risk
melanoma patients who did not receive these supplements. (The control
patients consisted of similar adjusted T3 cases selected from the Swedish
official registries and T2 patients from Germany.) Because 100% of these
high-risk patients were free of disease after almost 7 years, this provides
further piece of evidence of the potential value of dietary supplementation
in the cancer patient (Tallberg et al. 2000).
- Breast cancer patients commonly undergo chemotherapy to reduce the
risk of future metastasis. Despite the severe toxicity of chemotherapy,
many women experience aggressive metastatic disease and die. Once metastatic
disease manifests, the 5-year survival rate is only 15%. A review was
conducted of various chemotherapy regimens in order to ascertain the
percentages of objective remissions in metastatic breast cancer patients.
Of the drugs tested, 5-fl o u o rouracil (5-FU) came in last, but when
folic acid was added, objective remissions increased significantly (Kreienberg
1998).
- The drug 5-fluorouracil (5-FU) is commonly used in visceral cancers
(such as colon, liver, pancreatic), but has not shown a high degree
of efficacy. A randomized trial of patients with metastatic colorectal
carcinoma compared the effects of 5-FU administered alone and in combination
with folic acid. Both groups were comparable in respect to age, sex,
and numbers of metastases. Compared to the group receiving 5-FU by itself,
the patient group receiving the 5-FU plus folic acid experienced a 40%
arrest of tumor growth and a 76% overall reduction in tumor progression
indicating a 47% difference between the 5-FU and folate group and the
5-FU group. Survival time in the group receiving the 5-FU plus folic
acid was 47% greater than the group receiving the 5-FU by itself. The
addition of folic acid to this chemotherapy drug regimen resulted in
an improvement in the therapeutic profile and a significant prolongation
of the survival time (Loffler et al. 1992).
|
|
5-FU |
Folic acid and 5-FU
|
Difference |
| Complete or partial
remission |
9% |
versus 16% |
7% |
| Arrest of tumor growth
|
20% |
versus 60% |
40% |
| Progression |
71% |
versus 24% |
47% |
| Total |
100% of patients in group
|
100% of patients in group
|
|
- Advanced cancer patients exhibit multifaceted defects in their immune
capacity that are likely to contribute to an increased susceptibility
to infections and disease progression. This immune impairment also constitutes
a barrier to effective immunotherapeutic interventions. A chronic inflammatory
condition associated with increased oxidative stress has been suggested
as one of the responsible mechanisms behind the tumor-induced immune
suppression. A study was conducted on 12 advanced colorectal cancer
patients to ascertain if supplementation with the antioxidant vitamin
E could enhance immune functions. These colorectal cancer (Dukes's C
and D) patients received a daily dose of 750 mg of vitamin E beginning
2 weeks prior to intervention with chemotherapy or radiation treatment.
The results showed that short-term supplementation with vitamin E led
to increased CD4:CD8 ratios and enhanced capacity of their T-cells to
produce the T helper 1 cytokines, interleukin 2, and IFN-gamma (Malmberg
et al. 2002).
There are other human studies showing a benefit when cancer patients
take dietary supplements. We could find no studies on MEDLINE indicating
a detrimental effect. The findings from animal studies (reported on next)
support the positive human findings that show that dietary supplements
appear to enhance survival.
Animal Research on Cancer and Dietary Supplements
To obtain additional information about what happens when an organism
afflicted with cancer is administered dietary supplements, we extended
our MEDLINE search to in vivo animal studies. As was done with
the human study search, keywords were aimed at accessing all peer-reviewed
published studies relating to the effects of dietary supplements on animals
with different forms of cancer. The criteria for studies selected were
that the dietary supplements had to show an effect on survival. Below
is a synopsis of the MEDLINE findings:
- A debate among medical oncologists relates to the combined use of
certain dietary supplements and chemotherapy. A study on rat mammary
tumors provided some interesting data but also revealed part of the
controversy. In this study, rats were administered one of three chemotherapy
drugs (5-FU, doxorubicin, or cyclophosphamide) and then provided with
a wide dosage range of folic acid. In the folic acid-deficient group,
tumor growth was impeded. However, when higher amounts of folic acid
were administered, even greater tumor growth-inhibiting effects were
observed. When looking at the data, low folate inhibited tumor growth
by an average of 41%, moderate folic acid supplementation inhibited
tumor growth by an average of 67%, and very high folic acid administration
resulted in an average of 75% in tumor inhibition. Folic acid supplementation
doubled the efficacy of one of the drugs (cyclophosphamide) and improved
survival in the 5-FU treated animals (Branda et al. 1998).
- In a group of mice with ascites sarcoma, a four- to six-fold surplus
of folic acid in oral application reduced the toxicity of the chemotherapy
drug methotrexate. Moreover, adding these high amounts of folic acid
into their drinking water prolonged the survival of these mice (Motycka
et al. 1975).
- In a group of mice bearing leukemias and solid tumors, a combination
of oxidized vitamin C and vitamin B12 inhibited division of the cancer
cells. The mice were injected with the vitamins and after 19 days, all
of the controls had died, whereas more than 50% of the mice were alive
after 60 days in the vitamin-treated group. This study demonstrated
that when B12 is combined with vitamin C, the cobalt nucleus of B12
attaches to vitamin C, forming cobalt ascorbate. Additional tests proved
that cobalt ascorbate plus vitamin C inhibited tumor cells (Poydock
1991).
- The effects of methylcobalamin (vitamin B12) were examined in mice
with liver, lung, and Ehrlich ascites tumor cells. The growths of tumors
in some groups of the mice were suppressed by the 7-day administration
and their survival was longer than that of untreated mice (Shimizu et
al. 1987). In a contradictory animal study, the effect of methylcobalamin
and vitamin B12 reduced the survival of rats with liver cancer. This
is the only study where vitamins actually inhibited survival (Kal'nev
et al. 1977).
- Cancer spreading (metastasizing) throughout the body often culminates
in death. Immune suppression is one mechanism that cancer cells use
to establish colonies (metastatic lesions). Scientists investigated
the effects of an antioxidant called astaxanthin in stress-induced,
immune suppressed in mice. When exposed to stress, the number of natural
killer cells (NK) and other immune cells was reduced and an increase
in liver lipid peroxidation was observed. After 4 days of astaxanthin
administration, immune dysfunction induced by stress improved. In this
same study, cancer cells were injected into mice and the effects of
tumor development and metastatic lesions were evaluated in response
to induced stress. Daily administration of astaxanthin for 14 days markedly
attenuated the promotion of hepatic metastasis induced by stress. The
results of this study suggest that the antioxidant, astaxanthin, improves
antitumor immune response by inhibiting lipid peroxidation induced by
stress (Kurihara et al. 2002).
Despite these studies indicating that supplements confer a significant
anticancer benefit, there are certain supplements that cancer patients
might consider avoiding, at least during active treatment. These issues
are addressed in the next section and in the protocols entitled Cancer
Chemotherapy and Cancer Radiation Therapy that appear
in this book.
Do Antioxidants (Concurrent with Conventional Therapy)
Bolster or Diminish Survival Odds?
Abram Hoffer, M.D., Ph.D., contends that the concept of antioxidants
decreasing the efficacy of chemotherapy is conveyed more and more by orthodox
oncologists. It is, in fact, speculated that the number of oncologists
opposed to patients taking antioxidants while receiving chemotherapy may
be as high as 75%.
Although antioxidant therapy is a hotly debated issue, the benefits derived
from chemotherapy are equally so. Even within the field of standard oncology,
there is debate as to the merit of chemotherapy except for in a small
number of cancers (Moss 1995).
Before one can claim that antioxidants should be withheld, credible evidence
should be presented showing that chemotherapy has merit. At the Comprehensive
Cancer Care 2001 Conference, it was reported that 31% of cancer patients
abandon chemotherapy before completion due to intolerable psychological
and physical stresses.
Amifostine, a synthetic variant of the amino acid cysteine, is prescribed
to reduce radiation toxicity. Amifostine reduces toxicity of treatment
without depreciating the anti-cancer effects (Mehta 1998). There is no
evidence of defusing the effects of radiotherapy with Amifostine (Perez
et al. 1998). Cardiozane (ICRF187), an antioxidant with 500 papers showing
its relative safety, is prescribed to counter Adriamycin toxicity (Alderton
et al. 1992). Mesna, another synthetic antioxidant, makes possible the
use of the anticancer drug Ifosfamide, which (otherwise) damages the urinary
system (Brock et al. 1979). Synthetic antioxidants, though somewhat toxic
in nature, do not generate controversy because they are physician-prescribed
and not patient-managed. It appears only orthomolecular or natural antioxidants
are potentially dangerous, according to mainstream oncologists.
Most natural antioxidants, including vitamin C, are under ongoing scrutiny
and often attack. The charges that vitamin C impairs the effects of chemotherapy
appear to have kindled from an interview conducted with Larry Norton,
a chemotherapist with a focus on breast disease at Memorial Sloan Kettering.
An account of the interview that ran on the front page of newspapers (in
1997) charged that Sloan Kettering researchers had found that vitamin
C blunted the effects of chemotherapy in breast cancer cells.
Dr. Charles Simone, a respected voice in natural medicine, clarified
the media hype by saying that researchers had simply determined that tumor
cells (injected with vitamin C) take up larger amounts of the nutrient
than noncancerous cells (Agus et al. 1999). The story that was ultimately
reported had a different slant, that is, because tumor cells are vitamin
C responsive, ascorbic acid stymies the effects of chemotherapy by neutralizing
free radicals , molecules produced by various chemotherapeutic drugs to
kill the cancer. Dr. Simone cautions that jumping from a fact (cancerous
cells take up more vitamin C) to a factoid (vitamin C interferes with
chemotherapy/radiation therapy) is an unfortunate leap that may have impeded
progress for many cancer patients.
Dr. Simone cited more than 350 studies, involving 2000 cancer patients
that showed that antioxidants extended the life span of cancer patients
and improved quality of life. One such study involved 50 early stage breast
cancer patients, some of whom were relegated to radiation therapy and
others to a combination of radiation and chemotherapy. All participants
(in union with conventional therapies) took large doses of nutrients.
More than 90% of both groups noted improvement in their physical symptoms,
cognitive ability, sexual function, general well-being, and life satisfaction.
Not one subject in either group reported a worsening of symptoms (Simone
et al. 2000).
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