Cancer Overview and Statistics

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.

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.