Download LESSON 5.4 WORKBOOK What are the consequences of cancer and cancer treatment?

LESSON 5.4 WORKBOOK
What are the consequences of
cancer and cancer treatment?
DEFINITIONS OF TERMS
Remission – the reduction of
cancer symptoms, often considered being “cancer-free”
Relapse – the return of symptoms of cancer following a period
of being disease-free.
For a complete list of defined
terms, see the Glossary.
Wo r k b o o k
Lesson 5.4
The previous lesson on cancer treatment compared the benefits and risks of three
types of cancer treatments that focus on the cancer cells themselves. However
cancer as a disease affects more than the malignant cells themselves. This lesson
will focus on the strategies that are available to treat the symptoms of cancer rather
than the cells themselves, and will also discuss strategies that can play a role in
preventing cancer developing in the first place.
Not all cancers respond to treatment
For most of history cancer was considered to be an untreatable disease, and it has only been within the
last few hundred years that the potential to treat, if not cure, has been realized. In fact the three most
successful types of cancer treatment we have available, surgery, radiation, and chemotherapy were
only developed within the last 100 years. It has become clear however that these treatments are still not
enough. Some cancers respond to them while others, particularly metastases do not. Understanding how
and why some cancers are so resistant to treatment is a major focus of cancer research.
As we saw in the last lesson we consider cancer has entered remission following treatment if detection
methods can find no evidence of the primary tumor and if disease symptoms have been eliminated or
much reduced. Cancers that are detected and treated early enough that they are not yet metastatic often
enter full remission. However even cancers that are detected early may only enter partial remission if
they are already metastatic. In this case the cells that have been spared may not be detectable but they
will continue to proliferate and the cancer will return once the number of cells or tumor burden increases.
In the meantime the disease symptoms may be reduced or even eliminated, but this is temporary until the
cancer recurs and the patient enters relapse.
MC Questions:
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1. Which of the following describes the
outcome of a cancer that is 'cured'?
aa. Reduction.
bb. Relapse.
cc. Remission.
dd. Return.
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LESSON READINGS
Notes:
Whether a cancer will remain in remission or will relapse is usually almost impossible to predict. From
what we have learned throughout this module it should be clear that the reason for this is that each
cancer evolves as a response to the selective pressures it is experiencing and this can be very variable
between individual tumors or even between cells in a single tumor. The flip side of this random evolution
however is that individual metastatic cells may very well randomly evolve traits that prevent them from
forming secondary tumors. In this case the patient will seem like they are experiencing full remission, even
though many metastatic cancer cells remain in the body. If these cells remain functionally useless they will
likely be killed by the immune system over time.
DEFINITIONS OF TERMS
Conventional treatment – any
treatment typically used by medical professionals to treat cancer
(i.e. surgery, radiation, and /or
chemotherapy).
Intervention study – a study
where one group is given a treatment to evaluate the effect of that
treatment on people.
Wo r k b o o k
Lesson 5.4
Figure 1: A model for the evolution of cancer
and how different treatments target cancer cells.
While surgery is able to remove all cancer cells
from an organ, it cannot remove metastatic cells,
much like radiation therapy (Rad.), which only
targets fast growing cells that are not metastatic.
Chemotherapy (Chemo.) can kill some metastatic
cells and some cells of the tumor, but is more
specific and limited to a subset of cells sensitive to
the drug.
Figure 1 shows transformation of a
normal cell over time, with the boxes
indicating the types of cells each type
of therapy targets. Surgery is the only
therapy that does not target how a
cancer cell functions and so it can
effectively remove all cancer cells in a
primary tumor, but not any metastatic
cells. Chemotherapy can kill metastatic
cells except those cells that resistant to
the chemotherapy (the grey metastatic
cell in the picture). If these resistant
cells are capable of entering secondary organs, they are likely to lead
to relapse. However, if they acquire
mutations that prevent them exiting
the bloodstream or entering organs,
remission will persist.
Whether a cancer will go into remission
or relapse depends most of all on
the driver mutations (red arrows in
Figure 1) that allow the cancer cells
to acquire traits that will overcome
selective pressure. Figuring out which
mutations are drivers in the hope of
developing more specific drugs is
another intense area of research.
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LESSON READINGS
DEFINITIONS OF TERMS
Alternative treatment – any
treatment that is not a mainstream treatment to cancer (i.e.
not surgery, radiation, chemotherapy) that is used instead of a
mainstream treatment.
Complementary treatment
– any treatment that is not a
mainstream treatment to cancer
(i.e. not surgery, radiation, chemotherapy) that is used along with a
mainstream treatment.
Antioxidant – a molecule that
inhibits the activity of reactive
oxygen species to damage DNA.
Anti-angiogenic compound
– any chemical that inhibits the
growth of blood vessels.
Wo r k b o o k
Lesson 5.4
Treating cancer as a disease
MC Questions:
Surgery, chemotherapy and radiation therapy are considered conventional treatments for cancer because their
effects have been rigorously examined through numerous
interventional studies. As we learned in the Metabolic
Disorders module, intervention studies are the gold standard
for determining whether a treatment is effective. In these
studies a population with a disease is provided with a treatment and the outcome is compared with a well-matched
control group who also have the disease but who don’t
receive the treatment, or receive a different treatment whose
outcomes are well known. Without this kind of intervenFigure 2: Yoga is one type of
tion study it is impossible to know whether any positive
alternative treatment that boosts
outcome is caused by the treatment or just correlated with
energy and helps the immune
it. Few of the many cancer ‘cures’ reported an advertised
system in cancer treatment.
on the internet and in the non-scientific media have been
subjected to this level of scrutiny and so it is impossible to
know what the enthusiastic endorsements these alternative
treatments often receive really mean. Some alternative treatments that have been studied — such as
the active ingredient in apricot pits – have not stood up to rigorous scrutiny, others — such as the Gerson
treatment, a strict organic diet with frequent coffee enemas, have never been examined. Patients who
rely exclusively on these kinds of alternative treatments are therefore taking a risk. In most cases it makes
no difference whether patients receiving conventional treatments also pursue alternative treatments, but
in some cases they may interfere with the conventional therapy. It is for this reason that physicians ask
patients to inform them of all the therapies they are using.
2. What would you need to show an
alternative treatment is a useful
strategy to treat cancer? (Circle all
correct.)
aa. Evidence of efficacy in
intervention study.
bb. Number of people using
treatment.
cc. Number of articles written about
treatment.
dd. A mechanism to explain how
treatment works.
However, there are intervention studies that show some alternative treatments do work. These include
yoga, exercise, acupuncture, acupressure, hypnosis, massage, and musical therapy. It is unlikely that
these alternative approaches will lead to full cancer remission without the assistance of surgery, radiation, and chemotherapy, which is why these therapies are called complementary treatments. These
approaches may make the painful and traumatic process of mainstream cancer treatment more tolerable.
These complementary treatments have also been shown to improve the efficacy of the immune system,
which may help conventional treatments achieve cancer remission.
Finally, regulation of diet has been shown to be useful in improving cancer treatment outcomes.
Chemotherapy and radiation therapy have very toxic effects on the body, and consuming appropriate
nutrients is essential to recovering from their side effects.
3. True or false: Yoga, exercise, and
massage will improve the efficacy of
conventional treatments if performed
with these treatments.
aa. True.
bb. False.
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LESSON READINGS
DEFINITIONS OF TERMS
Curative treatment – any type
of medical care given where a
cure to disease is considered an
achievable goal.
Diet also plays an important role in cancer prevention. For instance, a high fiber diet correlates with
protection against bowel cancer, but how this protection occurs is unclear. Also, consumption of foods
rich in antioxidants such as fish, tomatoes, legumes (peas, beans and soy), and dark chocolate, along
with drinking green tea and red wine has been shown to decrease cancer risk. Antioxidants are useful to
prevent cancer because they help prevent damage to DNA by carcinogens. Foods rich in antioxidants
are also known to contain natural anti-angiogenic compounds. So, consumption of foods that prevent
DNA damage and decrease angiogenesis is likely to decrease the development and spread of cancer.
4. True or False: Controlling what we
eat can prevent the development
AND progression of cancer.
aa. True.
bb. False.
Lastly, chronic infection by pathogens have been linked to certain types of cancer. For instance, Hepatitis
B is a known cause of liver cancer, and human papilloma virus (HPV) causes cervical cancer and
some oral cancers. These cancers can be easily avoided by vaccination against the virus. Furthermore,
Helicobacter pylori infection is responsible for an estimated 70-90% of all stomach cancers. Antibiotic
treatment of H. pylori before it becomes chronic is a good way to decrease the chance of developing
stomach cancer. Simple approaches to prevent infection are a good way of reducing cancer risk
significantly.
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Palliative treatment – treatment
for a disease that is considered
uncurable where the goal is to
reduce symptoms and decrease
pain and stress associated with
disease.
In conclusion, there are many steps that we can make to limit the development of early-onset cancer that
appears due to environmental causes and pathogens. Among these are:
Hospice – a program /shelter
that provides care to decrease
pain and symptoms for patients
as well as addressing emotional
and spiritual needs of the patient.
■■ Not smoking;
■■ Consuming less refined or fatty foods;
■■ Increasing exercise;
■■ Limiting exposure to UV radiation;
■■ Drinking less alcohol; and
■■ Getting vaccinated.
Much as we saw in Unit 1, these approaches will not guarantee that you won’t get cancer. They just
reduce the risk. And, since cancer treatment is still in its infancy, it makes more sense to take the easy
steps that prevent the development of cancer than rely on traumatic cancer treatment options.
Wo r k b o o k
Lesson 5.4
MC Questions:
What do I do if my cancer is incurable?
Surgery, radiation, and chemotherapy are performed with the intention of producing cancer remission,
and because of this, they are commonly called curative treatment. If cancer is not identified until it is
5. Which of the following is a significant
way to prevent the development of
cancer? (Circle all correct.)
aa. Smoking low-tar cigarettes.
bb. Vaccination against H. pylori.
cc. Avoiding tanning beds.
dd. Regular exercise.
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LESSON READINGS
late stage, it is very difficult to fully treat the disease, and at this point curing the cancer is unlikely. In
these instances, doctors recommend a shift in treatment strategy from curative treatment to palliative
treatment, or treatment that emphasizes a reduction of symptoms rather than focusing on curing disease.
DEFINITIONS OF TERMS
Bereavement care – the type of
care that provides psychological
support for friends, family and
loved ones who have lost someone to disease.
Figure 3: As individuals live with cancer progressing in severity, the
focus of treatment shifts from curative care to palliative care. Once the
disease has become so severe that full time medical care is necessary to
relieve symptoms, hospice care is recommended. After death, bereavement
care is recommended for friends and families of the patient to help deal
with psychological stress of losing a loved one.
Palliative treatment is not dissimilar from curative treatment, as surgery, radiation, and chemotherapy
are still offered, but not so aggressively as to cure the disease. In the case of palliative treatment, just
enough treatment is offered to relieve the symptoms of the patient. If the cancer continues to worsen in
disease severity and full-time medical care is necessary, it is recommended that patients enter hospice
care. Hospices are homes for individuals with significant medical needs where medical support is
readily available, but is intended for people with late stage disease. Hospice care has been shown to
be much cheaper than hospitalization, but also has been shown to extend life by 3 months more than
hospitalization.
Wo r k b o o k
Lesson 5.4
Once a patient passes away from cancer, it is important to provide support to the family and friends of
the patient. This is called bereavement care, which provides psychological support for those who lost a
loved one. The view of cancer treatment focusing on palliative, hospice, and bereavement care treats a
patient more as a person rather than just focusing on treating the cancer. One of the hardest aspects to
consider is the death of a loved one, and this holistic approach has been shown to not only increase the
life-span of individuals with cancer, but allows patients to make their own choices on how they should die.
MC Questions:
6. Which of the following is an outcome
of palliative treatment? (Circle all
correct.)
aa. Improvement in mental health.
bb. Reduction of tumor size.
cc. Remission of cancer.
dd. Reduction of pain.
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7. Which of the following treatments
are considered most useful for
patients with late-stage cancer?
(Circle all correct.)
aa. Bereavement care.
bb. Curative care.
cc. Hospice care.
dd. Palliative care.
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STUDENT RESPONSES
What is one advantage and one disadvantage of trying to treat cancer using a holistic approach including palliative and
alternative treatments?
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Remember to identify your
sources
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Wo r k b o o k
Lesson 5.4
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TERMS
TERM
For a complete list of defined
terms, see the Glossary.
Wo r k b o o k
Lesson 5.4
DEFINITION
Alternative treatment
Any treatment that is not a mainstream treatment to cancer (i.e. not surgery, radiation, chemotherapy) that is
used instead of a mainstream treatment.
Anti-angiogenic
compound
Any chemical that inhibits the growth of blood vessels.
Antioxidant
A molecule that inhibits the activity of reactive oxygen species to damage DNA.
Bereavement care
The type of care that provides psychological support for friends, family and loved ones who have lost
someone to disease.
Complementary
treatment
Any treatment that is not a mainstream treatment to cancer (i.e. not surgery, radiation, chemotherapy) that is
used along with a mainstream treatment.
Conventional treatment
Any treatment typically used by medical professionals to treat cancer (i.e. surgery, radiation, and /or
chemotherapy).
Curative treatment
Any type of medical care given where a cure to disease is considered an achievable goal.
Hospice
A program /shelter that provides care to decrease pain and symptoms for patients as well as addressing
emotional and spiritual needs of the patient.
Intervention study
A study where one group is given a treatment to evaluate the effect of that treatment on people.
Palliative treatment
Treatment for a disease that is considered uncurable where the goal is to reduce symptoms and decrease
pain and stress associated with disease.
Relapse
The return of symptoms of cancer following a period of being disease-free.
Remission
The reduction of cancer symptoms, often considered being “cancer-free”.
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