Neoplasia III: Tumour Development

Genetic alterations or mutations in the DNA code are responsible for the development of tumors or cancer.

Factors that originate outside the body, like carcinogens, chemicals, radiation, and certain viruses, can cause cancer.

Factors that originate within the body, such as inheritance and host factors like age, immune system, and hormones, can contribute to cancer development.

Genetic conditions that make individuals more susceptible to developing tumors due to impaired DNA repair mechanisms.

Conditions like Xeroderma pigmentosum and Ataxia telangiectasia are examples of inherited conditions.

Genes that regulate cell growth and division, and when they mutate, they can contribute to tumor development. They are often involved in signaling pathways that control cell proliferation.

Genes that normally suppress tumor formation. When inactivated or mutated, they lose their ability to control cell growth and division, leading to tumor development.

Cancer development involves a series of steps, including the initiation of mutations and the promotion of cell growth and division.

A disorder characterized by extreme sensitivity to sunlight, leading to skin cancer and other health problems.

A rare genetic disorder causing a deficiency in DNA repair mechanisms, especially in response to radiation damage. This can lead to developmental and immune problems.

A genetic disorder that affects the ability to repair DNA damage caused by cross-linking agents. This can lead to bone marrow failure, developmental problems, and an increased risk of cancer.

Radiation, chemicals, and viruses can all directly damage DNA, leading to mutations and cancer.

Exposure to low doses of radiation can lead to genomic instability, while high doses can cause double-strand breaks, translocations, and sometimes point mutations. Defective DNA repair mechanisms can further increase the risk of mutations.

Chemicals can cause various types of DNA damage, including base damage, single-stranded breaks, and imperfect repair leading to mutations. This can be a direct effect or require metabolic activation.

A chemical initiating agent causes permanent DNA damage and increased cancer risk. However, it may not be enough to induce a tumor on its own. A promoting agent, when applied after initiation, can contribute to tumor formation in initiated cells.

Directly acting chemicals, like alkylating agents, readily interact with DNA without metabolic conversion. Indirectly acting agents, like polycyclic hydrocarbons, require metabolic conversion to become ultimate carcinogens.

A gene that normally suppresses cell growth and division. When inactivated or mutated, it loses its ability to control cell growth, contributing to tumor formation.

A gene that encodes a protein involved in the repair of DNA damage. Mutations in these genes can increase the risk of cancer by allowing mutations to accumulate.

A common oncogene that is frequently mutated in colon and lung cancer. It's involved in intracellular signaling pathways that regulate cell growth and division.

A growth factor receptor oncogene frequently amplified in breast cancer. It's involved in cell signaling pathways that promote growth and division.

A tumor suppressor gene associated with childhood eye cancer. Inherited mutations can increase the risk of developing retinoblastoma and other cancers.

A key tumor suppressor gene known as the 'guardian of the genome'. Mutations in p53 are found in more than half of all cancers.

A gene involved in DNA repair by homologous recombination. Mutations can increase the risk of breast and other cancers.

Polycyclic aromatic hydrocarbons (PAHs) are a group of chemicals found in coal tar and cigarette smoke. One particularly important member is 3,4-benzopyrene, which is converted into its active form by the enzyme aryl carbonate hydroxylase.

Aromatic amines are chemicals used in rubber and aniline dye production. When metabolized, they can be converted into a form that can cause bladder cancer.

Nitrosamines are compounds formed from nitrates and nitrites found in food. They are linked to an increased risk of gastrointestinal cancer.

Hepatitis B virus is a major risk factor for the development of hepatocellular carcinoma, a type of liver cancer.

The Epstein-Barr virus (EBV) is associated with several cancers, including Burkitt’s lymphoma and nasopharyngeal carcinoma.

Human papillomavirus (HPV) is a common sexually transmitted infection linked to cervical cancer.

Asbestos fibers, when inhaled, can cause mesothelioma, a rare and aggressive cancer of the lining of the lungs and chest cavity.

Aflatoxins, produced by certain molds, can cause liver cancer.