Epidemiology of Cancer and Risk Factors

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

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

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

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

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

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

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

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.

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

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

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

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.

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.

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.

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.

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

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.

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.

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

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.

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.

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

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

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

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

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

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

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.

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

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.

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