Epidemiology of Cancer and Risk Factors
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Questions and Answers

How is the relative risk of developing familial cancers in siblings generally characterized?

  • No increased risk
  • Between 1-2 times higher
  • Between 3-4 times higher
  • Between 2-3 times higher (correct)

What typically results from the deletion of specific regions of chromosomes?

  • Amplification of tumor suppressor genes
  • Loss of particular tumor suppressor genes (correct)
  • Conversion of proto-oncogenes to oncogenes
  • Overexpression of normal proteins

Which type of tumor is mostly associated with chronic inflammation?

  • Carcinomas (correct)
  • Sarcomas
  • Neurofibromas
  • Benign tumors

Which of the following gene amplifications is commonly associated with breast cancer?

<p>HER2 (ERBB2) gene (C)</p> Signup and view all the answers

What distinguishes familial colonic cancers from familial adenomatous polyposis syndrome?

<p>Familial colonic cancers arise without preexisting benign polyps (A)</p> Signup and view all the answers

How are gene rearrangements often produced?

<p>Through chromosomal translocations or inversions (B)</p> Signup and view all the answers

Which of the following is NOT considered a predisposing condition for familial cancers?

<p>Inherited benign tumors (C)</p> Signup and view all the answers

What is a common result of gene amplification involving proto-oncogenes?

<p>Overexpression and hyperactivity of proteins (B)</p> Signup and view all the answers

Which conditions are typically associated with tumors arising due to chronic inflammation?

<p>Carcinomas and mesothelioma (B)</p> Signup and view all the answers

Which deletion is specifically associated with the loss of the TP53 gene?

<p>Deletion of 17p (B)</p> Signup and view all the answers

What factor is NOT considered a major environmental risk for cancer?

<p>Genetic predisposition (B)</p> Signup and view all the answers

Why is breast cancer significantly higher in the U.S. compared to Japan?

<p>Differences in dietary factors (D)</p> Signup and view all the answers

Which of the following cancers is most commonly associated with infectious agents?

<p>Liver cancer (D)</p> Signup and view all the answers

What age group has the highest frequency of cancer diagnoses?

<p>Ages 55-75 (D)</p> Signup and view all the answers

Which statement about familial cancers is true?

<p>Predisposition to familial tumors may be multifactorial. (C)</p> Signup and view all the answers

Which of the following pairs contributes significantly to increased cancer risk when combined?

<p>Alcohol and smoking (D)</p> Signup and view all the answers

What percentage of cancers globally is attributed to environmental factors?

<p>15% (B)</p> Signup and view all the answers

Which of the following cancers accounts for 10% of deaths under age 15?

<p>CNS tumors (C)</p> Signup and view all the answers

What is the primary outcome of oncogenic gene rearrangements?

<p>Formation of chimeric proteins that disrupt normal cell functions (B)</p> Signup and view all the answers

Which of the following is an example of an oncogenic gene rearrangement leading to a fusion gene?

<p>Myc gene translocation in Burkitt lymphoma from chr. 8 to chr. 14 (D)</p> Signup and view all the answers

What mechanism underlies the overexpression of the BCL2 gene in follicular lymphoma?

<p>Reciprocal translocation between chromosome 14 and 18 (C)</p> Signup and view all the answers

Which chromosomes are involved in the formation of the ABL-BCR hybrid gene in chronic myeloid leukemia?

<p>9 and 22 (A)</p> Signup and view all the answers

What role does the inappropriate activity of promoters or enhancers play in oncogenesis?

<p>They lead to the activation of oncogenes under abnormal conditions (B)</p> Signup and view all the answers

What must happen to both alleles of tumor suppressor genes for cellular transformation to occur?

<p>They must both be damaged. (C)</p> Signup and view all the answers

Which type of tumor suppressor gene is responsible for sensing genomic damage?

<p>Guardians (A)</p> Signup and view all the answers

What characterizes driver mutations in cancer genetics?

<p>They alter the function of cancer genes and contribute to cancer progression. (C)</p> Signup and view all the answers

Which of the following best describes passenger mutations in cancer?

<p>They do not affect cellular behavior and occur at random. (D)</p> Signup and view all the answers

Which of the following statements about genetic lesions in cancer is correct?

<p>Specific chromosomal abnormalities have been identified in most leukemias and lymphomas. (D)</p> Signup and view all the answers

What is the primary effect of point mutations that convert proto-oncogenes into oncogenes?

<p>They generally produce a gain of function. (B)</p> Signup and view all the answers

Which of the following best describes aneuploidy in the context of cancer genetics?

<p>Characterized by a chromosome number that is not a multiple of 23. (A)</p> Signup and view all the answers

Which tumor suppressor gene is most commonly affected by point mutations in cancer?

<p>TP53 (B)</p> Signup and view all the answers

How do passenger mutations differ from driver mutations in the context of cancer?

<p>Driver mutations exert positive influence on cancer progression. (B)</p> Signup and view all the answers

Which statement is true regarding the effect of aneuploidy in cancer cells?

<p>Aneuploidy increases the copy number of key oncogenes. (C)</p> Signup and view all the answers

Flashcards

Familial Cancers

Cancers that run in families and are often linked to the inheritance of mutated genes.

Familial Cancer Risk

The chance that a sibling will develop a specific cancer is increased by 2 to 3 times compared to the general population.

Familial Cancer Marker Phenotypes

Familial cancers are not associated with specific visible characteristics, such as certain physical traits.

Familial Cancer Precursor Lesions

Unlike some genetic disorders, familial cancers typically don't arise from pre-existing, non-cancerous growths.

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Immunodeficiency and Cancer

Conditions that weaken the immune system can increase the risk of cancer.

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Tumor Suppressor Genes

Genes that normally suppress cell growth and division. Loss of function in both copies of these genes is required for tumor development.

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Driver Mutations

Mutations that directly contribute to the development and progression of cancer.

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Passenger Mutations

Mutations that occur in genes that are not directly involved in cancer development. They are acquired during tumor growth but do not affect cellular behavior.

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"Governors" Tumor Suppressor Genes

Tumor suppressor genes that act as 'brakes' on cell proliferation, preventing uncontrolled cell growth.

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"Guardians" Tumor Suppressor Genes

Genes that are responsible for sensing genomic damage and initiating a repair response or apoptosis.

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Cancer Incidence

New cancer cases occurring in a population over a specific period.

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Environmental Factors and Cancer

The major risk factors for many cancers are environmental exposures. This highlights the potential to prevent cancer. Variation in cancer types across geographic locations reflect different environmental influences.

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Breast Cancer

The incidence of breast cancer is significantly higher (4-5 times) in the US and Europe compared to Japan. This suggests environmental factors play a role, possibly linked to increased estrogen exposure and other lifestyle factors.

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Stomach Cancer

Stomach cancer is 7 times more common in Japan than in the US, indicating differences in environmental risk factors. These differences could be linked to diet or other lifestyle factors.

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Liver Cancer

Liver cancer is prevalent in Africa but rare in the US. Infectious agents are a significant contributor to liver cancer worldwide. Geographical variations highlight different exposure patterns.

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Obesity and Cancer

Obesity is a key risk factor for several cancers. Excess body fat disrupts hormonal balances and cellular processes, increasing cancer susceptibility.

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Smoking and Cancer

Smoking is a major cause of lung cancer, accounting for 90% of deaths. It also increases the risk of cancers of the mouth, esophagus, pancreas, and bladder.

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Alcohol and Cancer

Alcohol consumption is an independent risk factor for various cancers, including oropharynx, liver, and esophagus cancers. The combination of alcohol and smoking further elevates the cancer risk.

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Gene Mutations

Changes in the DNA sequence of a gene. These alterations can be acquired during a person's lifetime or inherited from parents.

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Point Mutation

A type of gene mutation where there is a change in a single nucleotide (building block of DNA) within a gene. This can either activate or inactivate the protein product of the gene.

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Aneuploidy

A condition where the number of chromosomes in a cell is not a multiple of the haploid number (23). This can lead to an abnormal number of copies of certain genes, potentially promoting cancer development.

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Gene Amplification in Cancer

A section of a gene might be duplicated, leading to multiple copies. This causes overproduction of the protein the gene encodes.

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TP53 Gene Deletion in Cancer

The TP53 gene is a tumor suppressor, and its loss due to deletion of chromosome 17 can contribute to cancer development.

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Gene Rearrangement in Cancer

Chromosomes can break and rearrange, causing changes in gene expression. This can lead to the activation of proto-oncogenes, driving cancer.

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Deletion of RB Gene in Retinoblastoma

The RB gene is a tumor suppressor, and its deletion can lead to the development of retinoblastoma.

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NMYC Amplification in Neuroblastoma

The NMYC gene is often amplified in neuroblastoma, contributing to increased cell growth and tumor development.

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Oncogenic Gene Rearrangements

Oncogenic gene rearrangements involve the creation of fusion genes, which are hybrid genes produced by the joining of two different genes.

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How Fusion Genes Activate Oncogenes

Fusion genes can activate oncogenes in two ways: by removing them from normal regulatory elements to place them under the control of a highly active promoter or enhancer, or by encoding novel chimeric proteins.

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Philadelphia (Ph) Chromosome

The Philadelphia (Ph) chromosome, found in chronic myeloid leukemia, is a classic example of an oncogenic gene rearrangement.

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Mechanism of Ph Chromosome Formation

The Ph chromosome is created by a balanced, reciprocal translocation between chromosomes 9 and 22, leading to the fusion of the ABL oncogene on chromosome 9 with the BCR locus on chromosome 22.

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Consequences of ABL-BCR Fusion

The resultant ABL-BCR fusion gene leads to the activation of growth factor signaling pathways, contributing to the development of chronic myeloid leukemia.

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Study Notes

Epidemiology of Cancer

  • Cancer incidence is increasing globally.
  • WHO data (2012): 14.1 million new cases worldwide.
  • Prediction for 2035: 24 million new cases.
  • Environmental exposures are significant risk factors for many cancers.

Geographic Variations in Cancer Types

  • Geographic variations in cancer types exist.
  • Death rates for breast cancer are 4-5 times higher in the U.S. and Europe than in Japan.
  • Stomach cancer is 7 times higher in Japan than in the U.S.
  • Liver cancer is common in Africa but rare in the U.S.

Major Environmental Factors

  • Diet: High death rates for breast cancer are observed in the U.S. and Europe compared to Japan.
  • Obesity: Linked to an increased risk of cancer.
  • Smoking: Responsible for 90% of lung cancer deaths and associated with other cancers (mouth, esophagus, pancreas, bladder).
  • Alcohol: Combined with smoking, increases the risk of cancer in upper airways and digestive tract.
  • Reproductive History: Prolonged estrogen exposure increases the risk of breast and endometrial cancer.
  • Infectious Agents: Responsible for 15% of cancers globally.

Age and Cancer

  • Cancer frequency increases with age (55-75 years).
  • Causes include accumulation of mutations and declining immune competence.

Childhood Cancer

  • Accounts for 10% of deaths under age 15.
  • Common lethal types include leukemias, CNS tumors, lymphomas, and soft tissue.

Familial Cancers

  • Common cancers (breast, ovarian, pancreatic, colon) have familial forms.
  • Transmission pattern is unclear, but predisposition is often dominant, meaning one affected gene can lead to a higher cancer risk.
  • Segregation analysis suggests multifactorial inheritance.
  • Genetic factors have been linked to some familial cancers.

Features of Familial Cancers

  • Early onset of tumors in close relatives.
  • Multiple tumors or bilateral tumors.
  • Familial cancers are not associated with specific phenotypes.
  • Some examples involving polyps and colon cancers, siblings having a relative risk between 2-3X.

Acquired Cancer Predisposing Conditions

  • Chronic inflammation.
  • Immunodeficiency states.
  • Precursor lesions.

Environmental and Genetic Interactions

  • Interactions between environmental and genetic factors.
  • Inherited traits vs acquired factors.

Genetic Lesions in Cancer

  • Genetic changes (single nucleotide mutations or chromosomal abnormalities).
  • Characteristic patterns in specific cancers.
  • Non-random abnormalities in leukemias and lymphomas.
  • Point mutations, gene amplifications, deletions and rearrangements.

Cancer Genes

  • Genes affected by genetic aberrations in cancers.
  • Causative mutations can be acquired (from environmental agents) or spontaneous.
  • Functional classes of cancer genes include oncogenes, genes regulating apoptosis, and tumor suppressor genes.

Gene Mutations in Cancer

  • Types of gene mutations, including point mutations, aneuploidy (chromosome number abnormalities), deletions, gene amplifications, and gene rearrangements.
  • These changes can alter the function of cancer genes, increasing the cancer risk.

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Epidemiology of Cancer PDF

Description

Explore the global incidence of cancer and the various environmental factors influencing its rise. This quiz delves into geographic variations in cancer types, significant risk factors such as diet, obesity, smoking, and alcohol, as well as the predictions for cancer cases in the future.

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