The invaluable nutrients found in foods not
only are essential for the prevention of potential future
tumour growth, but they also show a great response in cancer
patients when administered additionally to treatments such
as chemotherapy or radiotherapy. The effectiveness of these
elements and the methods by which they act upon cell damage
is still vaguely understood, even though their positive influence
in cancer prevention has been witnessed for decades. Nonetheless,
the future in research on this interaction looks bright and
promising.
Recent studies indicate that chemotherapy and radiotherapy
often damage DNA, which subsequently causes cell death,
whether by the process of apoptosis or necrosis, differing
in various morphological and biochemical events. Since treatments
with antioxidants stimulate apoptosis, there may be a synergistic
effect in the use of these elements with the respective
therapies. It is also suggested that this combination can
prevent specific toxicity arisen from the generation of
FR due to the drugs used in treatment.
Antioxidants and cancer therapies
Chemotherapy can cause apoptotic cell death in malignant
cells by the intake of antineoplastic (tumour-fighting)
drugs although some show resistance by antiapoptotic
mutations. Certain antioxidants such as quercetin have
proven capable to overcome this antiapoptosis blockade.
In addition, chemotherapy may reduce the patient's concentration
of antioxidants during treatment, which can reflect
a failure in defence mechanisms against oxidative damage.
Radiotherapy is based on the use of ionising radiation
that causes cell death through the formation of FR by
direct means in short amount of time, or indirectly
by inducing failures in cell division and inhibiting
cellular proliferation. It can also generate an apoptotic
scheme, deceptively through lipid peroxidation.
The use of antioxidants on top of these treatments
has demonstrated an increase in survival time for terminal
cancer patients. Their properties help enhance cytotoxic
effects and reduce toxicity to normal cells induced
by the treatments. By these means they improve the patient's
tolerance to the above therapies and also hyperthermia
(heat therapy), they strengthen the immune system, and
generally make the treatments more efficient.
It should be stressed that some antioxidants and other
nutrients might be more effective in conjunction with
one specific therapy than another. Their particular
assets and respective operating systems can more efficiently
target a specific pathway or even site of tumourigenesis.
For instance, it has been shown that Vitamin C works
better in patients with lung cancer, whereas selenium
has more efficacy against breast and colon cancers.
Fish oil improves tumour kill in hyperthermia and chemotherapy.
Ultimately, the ingestion of these agents is indispensable
for cancer patients, since these show drastic weight
loss and occasionally mal nutrition (cachexia). It is
necessary to increase the patient's consumption of antioxidants
and other essential nutrients to improve his/her well
being, both physically and mentally. Cachexia is thought
to be responsible for 30% to 60% of all cancer deaths.
Future implications
A healthy diet has always been an important issue regarding
disease prevention, but recent findings have helped scientists
to understand the particular mechanisms and key elements
involved in the fight against ailments, and left them eager
for more knowledge. The investigation prospective is immense,
but there are still many questions that remain unanswered:
Many epidemiological studies have been based on population
and prospective (cohort) studies. However, the need for
more in depth examination of the matter is vital. The
European Prospective Investigation into Cancer and Nutrition
(EPIC) is a multicentre European consortium that uses
the above-mentioned methods of investigation.
The selection of a model is central for an animal study
of carcinogenesis and the relationship with nutrition.
However, there is no single ideal animal model and valuable
insights are available from a diversity of animal models.
Transgenic mouse models are a future prospect, since they'll
present specific genetic susceptibilities for tumour development,
and therefore give out more accurate results from the
studies and in relation to a human perspective.
Phytochemicals found in herbs are also of great researchable
interest. They seem to detoxify the body from oxidative
damage and also stimulate and strengthen the immune system.
Many have scavenging properties, but so far only 1% have
been investigated.
Nutrition is a very promising, low-cost, non-toxic,
and scientifically valid approach to improving the outcome
from medical treatment, and shows great potential and efficiency
in the prevention of numerous disorders, including cancer.
