Description
The American Cancer Society (ACS) is a nationwide, community-based, voluntary health organization dedicated to eliminating cancer as a major health problem. Together with its supporters, ACS is committed to helping people stay well and get well by finding cures and by fighting back. Please add citations and References. Your initial answer to the DQ should contain about 150 words. See attachment.
Critical Thinking Questions:
- Imagine that a family friend or colleague has just been diagnosed with cancer. Explain how the American Cancer Society might provide education and support. What ACS services would you recommend and why?
- According to statistics published by the American Cancer Society, there will be an estimated 1.5 million new cancer cases diagnosed each year over the next decade. What factors contribute to the yearly incidence and mortality rates of various cancers in Americans? What changes in policy and practice are most likely to affect these figures over time
- Select a research program from among those funded by the American Cancer Society. Describe the program and discuss what impact the research will have on the prevention or treatment of cancer.
NRS-410V Lecture 2
Genetic Alterations and Cancer
Introduction
Congenital disorders or birth defects and many common diseases such as cancer are directly
related to alterations in the genetic structure of deoxyribonucleic acid (DNA). A general
knowledge of the principles of inheritance, the cell cycle, and the impact environmental
influences have on the genetic structure are crucial to understanding the disease processes,
ongoing research, and current disease treatments.
Aberrant Chromosomal Numbers
Congenital disorders or birth defects are more common than we realize. Many spontaneous
abortions are due to chromosomal defects, whether it is the number of chromosomes or the
construction of the chromosomes. Down syndrome, or trisomy of chromosome 21 (three copies
instead of two), is the most common chromosomal disorder that occurs during meiosis (Porth,
2007).
Aberrant Chromosomal Structure
During the process of meiosis, chromosomes often exchange blocks of DNA or alleles, causing
variation in the chromosomes. When the exchange is not precise, the alterations may prove fatal
to the gamete. This exchange of chromosomal material can also occur during mitosis and the cell
may die or the mutation may continue in the cell line. This translocation of genetic material is
implicated as the cause of many cancers. One example is the Philadelphia chromosome, in which
the translocation of DNA between chromosome 9 and chromosome 22 causes chronic myeloid
leukemia (CML). The translocation results in a novel protein, tyrosine kinase that promotes
unregulated growth of myeloid cells. A drug being used to treat CML, Gleevec (Novartis),
specifically blocks this tyrosine kinase, slowing the growth of the myeloid cells (McCance &
Heuther, 2006).
Neuroblastoma is associated with duplication of the MYCN gene. This MYCN gene is an
oncogene, meaning that in its nonmutated state, it directs and controls the proliferation of certain
cells. In its mutated state, proliferation is uncontrolled, which leads to tumors.
Single Gene Mutations
During mitosis and meiosis, the chromosomes are copied exactly. If one or more of the base
pairs in the DNA sequence of a gene is altered, there is the possibility of a point mutation in that
gene. This single defective gene on one chromosome may cause serious alterations in the
functioning of the body, such as Marfan’s syndrome. This is an autosomal dominant gene and has
a 50% chance of being transmitted to offspring. The BRCA1 and BRCA2 genes are autosomal
dominant and are linked with breast cancer. The BRCA1 is found on chromosome 17, while the
BRCA2 is found on chromosome 13. The HER-2/neuis also implicated in breast cancer. With
overexpression, this gene causes excessive growth signals to the nucleus. The drug trastuzumab
(Herceptin), a monoclonal antibody, is used to treat women who have the HER-2/neu alteration
because it blocks the receptors for growth factor.
Mutations of the ras gene family prevents the breakdown of GTP, which then allows the
cytoplasmic signaling molecules to remain active and stimulate cell growth inappropriately.
Lung cancer, leukemia, colon cancer, and ovarian cancer are all linked to the ras gene (Copstead
& Banasik, 2005). The p53 gene or tumor suppressor gene is responsible for apoptosis–or
programmed cell death–and the repair of damaged DNA. This gene helps maintain the
appropriate number of cells within tissues. A mutation of this gene allows the cells with damaged
DNA to live and become more aggressive. Many breast cancers have one or all of these
mutations, plus a few more. The p53 gene mutation is also linked to colon cancer and lung
cancer.
Autosomal recessive diseases require both copies of the gene to be defective. Cystic fibrosis and
phenylketonuria (PKU) are prime examples of autosomal recessive genes. These disorders relate
to enzymes that are incorrectly made rather than run-away cell growth. Punett squares and
pedigree charts demonstrate the inheritance patterns of either recessive or dominant genes.
Genetics and Common Diseases
Heart disease, hypertension, diabetes, and many psychiatric disorders have a familial tendency
which is linked to genetics. In coronary heart disease, lipids are highly involved in the formation
of atherosclerotic plaques. Twenty or more genes have been identified that play key roles in lipid
formation, transport, coagulation, and hypertension (McCance & Heuther, 2006). An
angiotensinogen gene has been implicated as a cause for hypertension and preeclampsia. These
altered genes along with other environmental and lifestyle risk factors increase the likelihood of
developing the disease.
In type I diabetics, the HLA-DR3 and/or HLA-DR4 allele have been identified. Alterations of
genes around the insulin gene on chromosome 11 also increase the risk of developing type I
diabetes (McCance & Heuther, 2006). For type 2 diabetes, several genes have been identified
that may increase the susceptibility. One gene is involved in adipocyte differentiation and
glucose metabolism, while mutation of the glucokinase gene alters glucose conversion in the
pancreas.
Environmental and Lifestyle Risk Factors
Environmental Risk Factors
With billions and billions of cells replicating, it is amazing that the process does not incur more
errors. Environmental influences increase the risk of errors in replication. Known chemical
carcinogens include benzopyrene, which is found in foods fried in fat. Nitrosamines found in
smoked, salted, and cured foods are also powerful carcinogens. The tars and nicotines in
cigarettes are also cancer promoters. In addition, the ultraviolet (UV) rays of the sun can cause
mutation of the p53 gene, thereby causing squamous cell carcinoma and a mutation in the p16
gene related to melanoma. The UV light also activates tumor necrosis factor-α (TNF-α), which
seems to reduce the immune surveillance system (McCance & Heuther, 2006).
Lifestyle Risk Factors
Obesity has been linked to increasing the risk of cancer. The adipose tissue produces enzymes
that increase the levels of free estradiol and testosterone. The receptors react to the increased
levels by causing cellular proliferation and inhibiting apoptosis (McCance & Huether, 2006),
increasing the risk of tumor development.
Viruses such as human papillomavirus (HPV), hepatitis B virus, and the Epstein-Barr virus have
been associated with cancer. The DNA of HPV becomes integrated into the nucleus of cervical
cells and directs the proliferation of the virus.
Cell Cycle
Now that the chromosomal and gene mutations have been discussed, the process of cell division
and growth as it relates to cancer needs to be understood. Cells that replicate have a five-phase
cell cycle. During the S phase of the cell cycle, chromosomes are replicated. It is during this
phase that environmental factors can affect the exact replication and cause mutations. The end of
the G2 phase allows for a quality control check of the replication. Alterations of the kinases that
control this checkpoint allow mutations to continue rather than be corrected, increasing the
chances of cancer.
Chemotherapy agents have been developed that act on different phases of the cell cycle with the
intent of blocking the replication of the cancerous cell along with normal cells. Methotrexate, an
antimetabolite, enters the cell and inhibits DNA synthesis. Cyclophosphamide, an alkylating
agent, causes the DNA strands to cross-link, preventing normal use of the DNA, as well as its
replication. Tamoxifen blocks the estrogen receptor cells–preventing DNA synthesis–and the
cells remain in the G0 or G1 phase rather than replicating.
Tumor Cell Transformation
Promotion Stage
Once a cell has survived one gene alteration, it must be able to continue to replicate and survive.
Promotion is the stage in which the altered cells proliferate. In the progression stage, cancer cells
often lose their ability to function and are not like the original tissue cells. These cells are
considered anaplastic. Contact inhibition is lost and the cancer cells overwhelm the area in which
they began. These malignant cells secrete proteases that destroy healthy cells and allow space for
the cancerous cells to grow.
Cancer Cell Growth
Continued growth of the cancer cells depends on an adequate blood supply. Tumor cells can
secrete vascular endothelial growth factor (VEGF) along with other growth factors that promote
angiogenesis. As the blood supply increases to the tumor, the metastatic potential increases.
Research is directed toward developing agents that can block the enzymes that support
angiogenesis. Without a good blood supply, cancer cells die.
Cancer Expansion
Cancer cells do not adhere to each other as do the cells in normal tissue. Given a good blood
supply or a lymphatic channel, the cancer cells can break away from the primary site and
metastasize to other areas in the body. It may take years for the cancer cells to overcome the
normal cells in the new site, so they can go undetected.
Cancer Signs and Symptoms
Early Stages
In the early stages of cancer, there are usually not noticeable symptoms. Fatigue-like pain is very
subjective and the reason for the fatigue is being researched. Pain is due to inflammation,
stretching of visceral surfaces, compression of nerve endings, and bone metastasis. In addition,
pain control is an ongoing problem in treating patients with cancer.
Later Stages
Cachexia or severe malnutrition is found in the later stages of cancer and is often the cause of
death. TNF-α produced by macrophages has been implicated as a cause for the depression of
protein synthesis and the increase in protein degradation. Anemia is also a common finding, as
are leucopenia and thrombocytopenia due to suppression of the bone marrow.
Cancer Therapy Research
Throughout the lecture, different treatment therapies have been mentioned. Surgery,
chemotherapy, and radiation continue as mainstay treatments. Immunomodulation therapy uses
interferons, interleukins, monoclonal antibodies, and hematopoietic growth factors to destroy
cancer cells. The interferons inhibit cancer cell proliferation and stimulate NK cells, T cells, and
macrophages. Interleukin 2 stimulates the proliferation of T cells, NK cells, and macrophages,
increasing the number available to destroy cancer cells. Monoclonal antibodies are specific to
certain tumor cell receptors blocking growth factors as well as identifying the cell to the NK cells
as foreign. The hematopoietic growth factors are used to stimulate production of neutrophils,
macrophages, erythrocytes, and platelets in order to support the tissues during the tumor
destruction.
Research into gene therapy involves attempting to alter the genetic structure of the tumor cells,
making them more susceptible to the immune system, or replacing the missing p53 gene by
transporting it into the tumor cell using an inactivated virus. Stem cell transplant involves
harvesting stem cells from the bone marrow of a closely matched donor and transplanting the
stem cells. The therapy serves to restore the function of the once cancerous bone marrow. In
addition, research is being done on vaccines for specific cancers. The HPV vaccine, Gardisil, is a
beginning, whereas another area of research is being studied to inhibit the protelytic enzymes
that allow the cancer cells to expand and metastasize.
Conclusion
Understanding genetics is important for the clinician who works with families who are or wish to
become pregnant in order to explain the risks of birth defects and other genetically linked
diseases. Every nurse needs to be able to educate patients on the environmental and lifestyle risks
associated with cancer along with the genetic link. For those patients who are already being
treated for cancer, the nurse should be able to explain how the medications and radiation help
treat the disease.
References
Copstead, L. E., & Banasik, J. L. (2005). Pathophysiology (3rd ed.). St. Louis, MO: Saunders
Elsevier.
McCance, K. L., & Huether, S. E. (2006). Pathophysiology: The biological basis fordisease in
adults and children (5th ed.). St. Louis, MO: Mosby Elsevier.
Porth, C. M. (2007). Essentials of pathophysiology: Concepts of altered health states (2nd ed.).
Philadelphia, PA: Lippincott Williams & Wilkins.
© 2013. Grand Canyon University. All Rights Reserved.
Purchase answer to see full
attachment
Genetic Alterations and Cancer
Introduction
Congenital disorders or birth defects and many common diseases such as cancer are directly
related to alterations in the genetic structure of deoxyribonucleic acid (DNA). A general
knowledge of the principles of inheritance, the cell cycle, and the impact environmental
influences have on the genetic structure are crucial to understanding the disease processes,
ongoing research, and current disease treatments.
Aberrant Chromosomal Numbers
Congenital disorders or birth defects are more common than we realize. Many spontaneous
abortions are due to chromosomal defects, whether it is the number of chromosomes or the
construction of the chromosomes. Down syndrome, or trisomy of chromosome 21 (three copies
instead of two), is the most common chromosomal disorder that occurs during meiosis (Porth,
2007).
Aberrant Chromosomal Structure
During the process of meiosis, chromosomes often exchange blocks of DNA or alleles, causing
variation in the chromosomes. When the exchange is not precise, the alterations may prove fatal
to the gamete. This exchange of chromosomal material can also occur during mitosis and the cell
may die or the mutation may continue in the cell line. This translocation of genetic material is
implicated as the cause of many cancers. One example is the Philadelphia chromosome, in which
the translocation of DNA between chromosome 9 and chromosome 22 causes chronic myeloid
leukemia (CML). The translocation results in a novel protein, tyrosine kinase that promotes
unregulated growth of myeloid cells. A drug being used to treat CML, Gleevec (Novartis),
specifically blocks this tyrosine kinase, slowing the growth of the myeloid cells (McCance &
Heuther, 2006).
Neuroblastoma is associated with duplication of the MYCN gene. This MYCN gene is an
oncogene, meaning that in its nonmutated state, it directs and controls the proliferation of certain
cells. In its mutated state, proliferation is uncontrolled, which leads to tumors.
Single Gene Mutations
During mitosis and meiosis, the chromosomes are copied exactly. If one or more of the base
pairs in the DNA sequence of a gene is altered, there is the possibility of a point mutation in that
gene. This single defective gene on one chromosome may cause serious alterations in the
functioning of the body, such as Marfan’s syndrome. This is an autosomal dominant gene and has
a 50% chance of being transmitted to offspring. The BRCA1 and BRCA2 genes are autosomal
dominant and are linked with breast cancer. The BRCA1 is found on chromosome 17, while the
BRCA2 is found on chromosome 13. The HER-2/neuis also implicated in breast cancer. With
overexpression, this gene causes excessive growth signals to the nucleus. The drug trastuzumab
(Herceptin), a monoclonal antibody, is used to treat women who have the HER-2/neu alteration
because it blocks the receptors for growth factor.
Mutations of the ras gene family prevents the breakdown of GTP, which then allows the
cytoplasmic signaling molecules to remain active and stimulate cell growth inappropriately.
Lung cancer, leukemia, colon cancer, and ovarian cancer are all linked to the ras gene (Copstead
& Banasik, 2005). The p53 gene or tumor suppressor gene is responsible for apoptosis–or
programmed cell death–and the repair of damaged DNA. This gene helps maintain the
appropriate number of cells within tissues. A mutation of this gene allows the cells with damaged
DNA to live and become more aggressive. Many breast cancers have one or all of these
mutations, plus a few more. The p53 gene mutation is also linked to colon cancer and lung
cancer.
Autosomal recessive diseases require both copies of the gene to be defective. Cystic fibrosis and
phenylketonuria (PKU) are prime examples of autosomal recessive genes. These disorders relate
to enzymes that are incorrectly made rather than run-away cell growth. Punett squares and
pedigree charts demonstrate the inheritance patterns of either recessive or dominant genes.
Genetics and Common Diseases
Heart disease, hypertension, diabetes, and many psychiatric disorders have a familial tendency
which is linked to genetics. In coronary heart disease, lipids are highly involved in the formation
of atherosclerotic plaques. Twenty or more genes have been identified that play key roles in lipid
formation, transport, coagulation, and hypertension (McCance & Heuther, 2006). An
angiotensinogen gene has been implicated as a cause for hypertension and preeclampsia. These
altered genes along with other environmental and lifestyle risk factors increase the likelihood of
developing the disease.
In type I diabetics, the HLA-DR3 and/or HLA-DR4 allele have been identified. Alterations of
genes around the insulin gene on chromosome 11 also increase the risk of developing type I
diabetes (McCance & Heuther, 2006). For type 2 diabetes, several genes have been identified
that may increase the susceptibility. One gene is involved in adipocyte differentiation and
glucose metabolism, while mutation of the glucokinase gene alters glucose conversion in the
pancreas.
Environmental and Lifestyle Risk Factors
Environmental Risk Factors
With billions and billions of cells replicating, it is amazing that the process does not incur more
errors. Environmental influences increase the risk of errors in replication. Known chemical
carcinogens include benzopyrene, which is found in foods fried in fat. Nitrosamines found in
smoked, salted, and cured foods are also powerful carcinogens. The tars and nicotines in
cigarettes are also cancer promoters. In addition, the ultraviolet (UV) rays of the sun can cause
mutation of the p53 gene, thereby causing squamous cell carcinoma and a mutation in the p16
gene related to melanoma. The UV light also activates tumor necrosis factor-α (TNF-α), which
seems to reduce the immune surveillance system (McCance & Heuther, 2006).
Lifestyle Risk Factors
Obesity has been linked to increasing the risk of cancer. The adipose tissue produces enzymes
that increase the levels of free estradiol and testosterone. The receptors react to the increased
levels by causing cellular proliferation and inhibiting apoptosis (McCance & Huether, 2006),
increasing the risk of tumor development.
Viruses such as human papillomavirus (HPV), hepatitis B virus, and the Epstein-Barr virus have
been associated with cancer. The DNA of HPV becomes integrated into the nucleus of cervical
cells and directs the proliferation of the virus.
Cell Cycle
Now that the chromosomal and gene mutations have been discussed, the process of cell division
and growth as it relates to cancer needs to be understood. Cells that replicate have a five-phase
cell cycle. During the S phase of the cell cycle, chromosomes are replicated. It is during this
phase that environmental factors can affect the exact replication and cause mutations. The end of
the G2 phase allows for a quality control check of the replication. Alterations of the kinases that
control this checkpoint allow mutations to continue rather than be corrected, increasing the
chances of cancer.
Chemotherapy agents have been developed that act on different phases of the cell cycle with the
intent of blocking the replication of the cancerous cell along with normal cells. Methotrexate, an
antimetabolite, enters the cell and inhibits DNA synthesis. Cyclophosphamide, an alkylating
agent, causes the DNA strands to cross-link, preventing normal use of the DNA, as well as its
replication. Tamoxifen blocks the estrogen receptor cells–preventing DNA synthesis–and the
cells remain in the G0 or G1 phase rather than replicating.
Tumor Cell Transformation
Promotion Stage
Once a cell has survived one gene alteration, it must be able to continue to replicate and survive.
Promotion is the stage in which the altered cells proliferate. In the progression stage, cancer cells
often lose their ability to function and are not like the original tissue cells. These cells are
considered anaplastic. Contact inhibition is lost and the cancer cells overwhelm the area in which
they began. These malignant cells secrete proteases that destroy healthy cells and allow space for
the cancerous cells to grow.
Cancer Cell Growth
Continued growth of the cancer cells depends on an adequate blood supply. Tumor cells can
secrete vascular endothelial growth factor (VEGF) along with other growth factors that promote
angiogenesis. As the blood supply increases to the tumor, the metastatic potential increases.
Research is directed toward developing agents that can block the enzymes that support
angiogenesis. Without a good blood supply, cancer cells die.
Cancer Expansion
Cancer cells do not adhere to each other as do the cells in normal tissue. Given a good blood
supply or a lymphatic channel, the cancer cells can break away from the primary site and
metastasize to other areas in the body. It may take years for the cancer cells to overcome the
normal cells in the new site, so they can go undetected.
Cancer Signs and Symptoms
Early Stages
In the early stages of cancer, there are usually not noticeable symptoms. Fatigue-like pain is very
subjective and the reason for the fatigue is being researched. Pain is due to inflammation,
stretching of visceral surfaces, compression of nerve endings, and bone metastasis. In addition,
pain control is an ongoing problem in treating patients with cancer.
Later Stages
Cachexia or severe malnutrition is found in the later stages of cancer and is often the cause of
death. TNF-α produced by macrophages has been implicated as a cause for the depression of
protein synthesis and the increase in protein degradation. Anemia is also a common finding, as
are leucopenia and thrombocytopenia due to suppression of the bone marrow.
Cancer Therapy Research
Throughout the lecture, different treatment therapies have been mentioned. Surgery,
chemotherapy, and radiation continue as mainstay treatments. Immunomodulation therapy uses
interferons, interleukins, monoclonal antibodies, and hematopoietic growth factors to destroy
cancer cells. The interferons inhibit cancer cell proliferation and stimulate NK cells, T cells, and
macrophages. Interleukin 2 stimulates the proliferation of T cells, NK cells, and macrophages,
increasing the number available to destroy cancer cells. Monoclonal antibodies are specific to
certain tumor cell receptors blocking growth factors as well as identifying the cell to the NK cells
as foreign. The hematopoietic growth factors are used to stimulate production of neutrophils,
macrophages, erythrocytes, and platelets in order to support the tissues during the tumor
destruction.
Research into gene therapy involves attempting to alter the genetic structure of the tumor cells,
making them more susceptible to the immune system, or replacing the missing p53 gene by
transporting it into the tumor cell using an inactivated virus. Stem cell transplant involves
harvesting stem cells from the bone marrow of a closely matched donor and transplanting the
stem cells. The therapy serves to restore the function of the once cancerous bone marrow. In
addition, research is being done on vaccines for specific cancers. The HPV vaccine, Gardisil, is a
beginning, whereas another area of research is being studied to inhibit the protelytic enzymes
that allow the cancer cells to expand and metastasize.
Conclusion
Understanding genetics is important for the clinician who works with families who are or wish to
become pregnant in order to explain the risks of birth defects and other genetically linked
diseases. Every nurse needs to be able to educate patients on the environmental and lifestyle risks
associated with cancer along with the genetic link. For those patients who are already being
treated for cancer, the nurse should be able to explain how the medications and radiation help
treat the disease.
References
Copstead, L. E., & Banasik, J. L. (2005). Pathophysiology (3rd ed.). St. Louis, MO: Saunders
Elsevier.
McCance, K. L., & Huether, S. E. (2006). Pathophysiology: The biological basis fordisease in
adults and children (5th ed.). St. Louis, MO: Mosby Elsevier.
Porth, C. M. (2007). Essentials of pathophysiology: Concepts of altered health states (2nd ed.).
Philadelphia, PA: Lippincott Williams & Wilkins.
© 2013. Grand Canyon University. All Rights Reserved.
Purchase answer to see full
attachment
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