intro to cancer 2 Flashcards
how does cancer kills?
Interferes with normal organ function
- blockage / obstruction
- deprivation of nutrients
- pressure
Interferes with metabolic processes
- malnutrition
- calcium changes
- liver enzyme function
- production of blood cells
- hormone production
Muscle wasting
what causes cancer?
A single mutation leading to a single acquired property such as increased proliferation is not enough to lead to cancer.
A single cell has to be able to acquire (usually after multiple mutations) most or all of the hallmarks in order to progress to cancer.
This takes time!
DNA in a typical cell is damaged around 10,000 times per day.
Most of this DNA damage is repaired, but the DNA repair mechanisms are not perfect and some damage is occasionally missed leading to a mutation.
Mutations occur randomly throughout the genome.
In many cases these mutations are in non-coding regions or in regions of genes where they have no effect.
Where these mutations occur in key genes such as proto-oncogenes or tumour suppressor genes, they can lead to cancer.
what are the types of mutation?
In gene coding regions; point mutations or small insertions/deletions
Alterations in transcription/splicing
Amplifications/deletions of chromosomal regions
Chromosomal translocations
Gains and losses of whole chromosomes
Changes in DNA modification, eg., DNA methylation
what causes mutations?
UV and other types of radiation
Free radicals produced during metabolic processes
Viruses
Chemicals (smoking, asbestos, food etc)
Copying / repair errors (often inherited)
In cancer, accumulated mutations can lead to genome instability and an increased likelihood of further mutations.
what is the stages of cancer development?
There are a number of stages in the development of cancer.
The first stage is called initiation in which the first mutations promoting increased proliferation occurs.
The next stage is promotion, in which additional mutations promote further proliferation. These two stages are known as carcinogenesis.
This is followed by tumour progression which sees growth and invasion of the tumour.
what is the stages of cancer and survival
Identifying how far a tumour has progressed (stage) is important for determining the treatment and for prognosis.
In many cases tumours are staged from 1-4 (or I-IV) e.g. breast cancer, colorectal cancer.
Another grading scheme is the TNM scheme. This stands for Tumour (how far the tumour has grown locally; score 1-4),
Nodes (is there any invasion to lymph nodes, score 0-2), Metastasis (has the tumour spread to distant sites; score 0 or 1).
why are survival rates improving?
Earlier diagnosis
screening scanning biomarkers
Better treatments
surgery radiotherapy chemotherapy
what is cancer screening programmes?
Early detection, diagnosis and treatment is key to improving patient prognosis
Self-checks
Skin cancer
Breast cancer
Testicular cancer
NHS screening programmes
Bowel cancer - Men and women (60-75 years)
Cervical cancer - Women (25-65 years)
Breast cancer - Women (50-70 years)
what is the risk factors of cancer?
Risk factors associated with an increased incidence of cancer include age, genetics and exposure to risk factors
Smoking
Inactivity/lack of physical activity
Obesity
Alcohol
Diet - lack of fruit and vegetables, salt, processed foods, red meats)
Infections - Infections cause 18% cancers globally
what viruses causes cancer ?
papovavirus - warts
heapatitis B and C - liver cancer
herpesvirus - burkitts lymphoma
RNA -
Retrovirus - leukomemia
