Cancer Overview and Statistics

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary characteristic that differentiates oncogenes from proto-oncogenes?

Oncogenes have been mutated or overexpressed, leading to a gain of function. (correct)

Oncogenes result from the inactivation of tumor suppressor genes.

Oncogenes are involved in apoptosis while proto-oncogenes are not.

Oncogenes are always present in all cells while proto-oncogenes are not.

Which mechanism can NOT convert proto-oncogenes into oncogenes?

Gene Amplification

Gene Suppression (correct)

Point Mutations

Chromosomal Rearrangement

What results from gene amplification in the context of proto-oncogenes?

Hyperactive protein is made in normal amounts.

Normal protein production is greatly increased. (correct)

A loss of function mutation occurs.

Normal protein production decreases.

Which type of mutation is associated with a dominant gain of function phenotype in oncogenes?

Point mutation or amplification Signup and view all the answers

What type of alteration can cause overproduction of a fusion protein related to a proto-oncogene?

Chromosomal Rearrangement Signup and view all the answers

What triggers cell proliferation as an example of a growth factor?

PDGF Signup and view all the answers

What is the primary role of tumour suppressor genes?

To prevent inappropriate cell proliferation Signup and view all the answers

How many mutations are generally required in tumour suppressor genes to promote cancer development, according to the two-hit hypothesis?

Two mutations Signup and view all the answers

In sporadic retinoblastoma cases, what percentage occurs without any family history?

60% Signup and view all the answers

Which of the following best describes the nature of mutations in familial cancers compared to sporadic cancers?

Familial cancers are less frequent and hereditary. Signup and view all the answers

What is a characteristic of the Ras protein in the context of cancer?

It transduces signals for cell proliferation. Signup and view all the answers

Which of the following statements is false regarding the function of a tumour suppressor gene?

It promotes the expression of genes related to apoptosis. Signup and view all the answers

What is true about germline mutations in relation to cancer?

They are present in the egg or sperm. Signup and view all the answers

In retinoblastoma, what does a mutation in the retinoblastoma (Rb) gene signify?

It is a key step but not sufficient for tumor development. Signup and view all the answers

Which statement best describes the role of proto-oncogenes in cancer?

They stimulate cell proliferation. Signup and view all the answers

How does age impact cancer incidence according to cancer statistics?

Incidence rates are highest in older adults. Signup and view all the answers

What types of mutations are primarily associated with tumor suppressor genes?

Loss-of-function, recessive mutations. Signup and view all the answers

What is the general requirement for the development of most cancers?

At least 5-6 independent mutations. Signup and view all the answers

Which of the following best categorizes mutations as carcinogens?

Mutagens that directly cause cancer. Signup and view all the answers

In the context of cancer, what effect do tumor suppressor genes typically have?

They promote DNA repair. Signup and view all the answers

Which of the following statements about cancer is accurate?

Cancer involves a variety of diseases with diverse causes. Signup and view all the answers

Study Notes

Cancer Overview

Cancer is a genetic disease, mainly affecting the elderly population.
Cancer is characterized by uncontrolled cell division and the potential to invade surrounding tissues.
Cancer incidence increases with age.
Cancer development is a multi-stage process, with some cancers, like retinoblastoma, occurring in children.
Cancer is caused by mutations in cellular genes—both oncogenes and tumor suppressor genes.

Cancer Statistics

Approximately 385,477 new cancer cases occur annually in the UK (2017-2019 average)
More than half of new cancer cases are breast, prostate, lung, or bowel cancer (2017-2019 average).
The highest occurrence of cancer cases in the UK ranges from age 85 to 89 (2017-2019 average).

Cancer Types and Incidence

Many different cancer types exist.
The occurrence of cancer varies between different types and sexes.

Cancer and Age

Cancer incidence increases with age, as more mutations accumulate in cells.

Proto-oncogenes

Proto-oncogenes are normal cellular genes involved in cell growth and division.
Mutations or overexpression of proto-oncogenes can transform them into oncogenes.
Oncogenes drive uncontrolled cell proliferation.

Tumor Suppressor Genes

Tumor suppressor genes prevent uncontrolled cell proliferation.
These genes normally act as brakes on cell division.
Mutations in tumor suppressor genes can cause them to lose their function, allowing cells to divide uncontrollably.
An example of a tumor suppressor gene is p53. p53 regulates cell cycle, DNA repair, and apoptosis.
Mutations in p53 are implicated in ~50% of human cancers (e.g., breast, lung, colorectal, stomach).

Two-Hit Hypothesis (Retinoblastoma)

Retinoblastoma is a tumor of the retina that can occur both sporadically and hereditarily.
The two-hit hypothesis explains how a tumor suppressor gene mutation (Rb gene) can lead to retinoblastoma.
Sporadic retinoblastoma requires two somatic mutations in the Rb gene.
Familial retinoblastoma occurs when one Rb mutation is inherited. The second mutation is somatic.

BRCA1 and BRCA2

BRCA1 and BRCA2 are tumor suppressor genes crucial for normal DNA repair in cells.
Mutations in BRCA1/2 increase significantly the risk of early-onset breast cancer. Mutations tend to reduce the ability of the proteins to repair DNA damage.
Sporadic breast cancer occurs in older women, primarily with a single tumor appearing in a single breast.
Familial breast cancer occurs in younger women and often has multiple tumors in both breasts.
The proportion of hereditary breast cancer cases from BRCA1 mutations is 7%-10%.

Cell Cycle and Rb

Rb is a tumor suppressor that acts as a "brake" during the G1/S checkpoint of the cell cycle. It prevents cells from dividing when conditions aren't suitable.
Phosphorylation of Rb releases the brake.
Non-phosphorylated Rb binds to and disables E2F transcription factors. Phosphorylation releases it, allowing cells to proceed through the cell cycle.
Mutations can disrupt the cell cycle regulation and lead to tumor development.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz provides an overview of cancer, highlighting its genetic nature and the association with age. It includes statistics on incidence and prevalence across different types of cancer in the UK. Test your knowledge on the impact of age and genetic mutations on cancer development.