Oncology Flashcards
Oncology
The study and treatment of cancer (malignant tumours)
Onco = tumour, -ology = study of
Oncologist
A physician who practises oncology
Neoplasm
A mass of tissue that grows faster than normal in an uncoordinated manner
Neo = new, -plasia = growth
Tumour
Latin for ‘swelling’– used to describe a mass / growth of tissue. Can be either malignant or benign.
A tumour no longer responds to normal growth factors, growing faster than normal and in an uncoordinated manner
Tumour = swelling
Cancer statistics
The leading cause of death globally (nearly 10 million deaths per year).
Most common causes of cancer death in the world are; lung, colorectal, liver, stomach, breast
By 2040 – global burden is expected to grow to 27.5 million new cases and 16.3 deaths
More developed countries have higher cancer rates – links to environment, lifestyle, diet, medications and drugs
Cells and division; Mitosis and meiosis
Mitosis and meiosis are the processes of cellular growth and reproduction. Mitosis is the growth and repair of somatic cells
Meiosis is the process that produces sex cells (gametes)
Cells and division in cancer
All cells are differentiated and specialised. Cells are organised in a tissue and fulfil the tissue’s function
If cells become disorganised and grown in an uncontrolled manner, their function is lost. Cell architecture is key to observe in suspected neoplastic growth.
Cancer Biology; Genetics – Genetic mutations
Cancer occurs as a result of genetic mutations.
It is the result of an underlying cause.
The causes of cancer promote the mutations of multiple genes – it is essential to explore the interaction of the patient’s genes with the environment.
Cancer Biology; Genetics – Tumour suppression genes and oncogenes and angiotenesis
Tumour suppression genes (‘off switch’) become inactivated.
New genes called oncogenes (‘on switch’) are formed that cause over production of growth factors and increase cell division (divide at an uncontrolled & rapid pace)
Malignant cells can only grow 1-2mm3 without a blood supply, so undergo angiotenesis
Cancer Biology; Pro cancer environment
It is paramount to recognise the environment that cancer cells thrive in. The prime environment is:
1; Acidic
2; Anaerobic
3. Glucose rich
It is essential to consider the environment that we bathe our genes in. Genes load the gun, the environment is the trigger
Cancer Biology; Acidic Environment
Acidic environment; Red meats (sulphur = sulphuric acid), processed foods, dairy, sugar, salt and smoked foods add to the acidity of the body
Can assess pH – markers in saliva / urine
Cancer Biology; Anaerobic environment
Anaerobic environment; ‘Lacking Oxygen’. Consider stress (contracting muscles – O2), breathing (lack of 02), diet, exercise (sedentary – lactic acid)
Cancer Biology; Glucose rich environment
Glucose rich environment; Malignant cells are dependent on glucose for their own metabolism. These cells have many more glucose receptors on their membrane. Refined sugars are especially harmful – feed tumours.
Cell Cycle - contact inhibition
Proteins are normally produced by cells, which give it contact inhibition. Contact inhibition prevents cells dividing beyond the space available.
Cancerous cells lose contact inhibition.
Together with contact inhibition, cells have a programmed number of reproductive cycles.
Mutation
The change in the genetic information (change in DNA/ sequence / number)
Mutagen
An agent that changes the genetic information. Mutagens can be:
* Environmental hazards
* Chemicals (environmental, household, drugs, vaccines)
* Radiation (x-rays, microwaves, mobile phones)
* Viruses
* Inflammation
* Defective immunity
* Stress / emotional trauma
Cancer Causes: Carcinogen
A carcinogen is any cancer causing agent;
E.g. Nitrosamines, heavy metals, asbestos, x-rays, UV-rays
Cancer Causes; Carcinogenesis
Carcinogenesis is the process by which normal cells are transformed into cancer cells.
Only 5-10% of cancers are attributed to inherited genetic defects
90-95% of cancers are attributed to the environment and lifestyle
Generally causative factors can be difficult to establish because many cancers take many years to develop. Some tumours take 20-40 years.
Risk factors
Include:
* Genetic factors (e.g. BRCA) / family history
* Chronic inflammation, e.g. inflammatory bowel diseases, gastro-oesophageal reflux disease, gastritis, etc. Chronic inflammation promotes proliferation of cancer cells
* Radiation, e.g. environmental, medical, microwaves, phones
* Smoking, e.g. causes one mutation every 15 cigarettes
* Drugs and cosmetics, e.g. parabens
* GIT dysfunction, e.g. liver (detoxifies substances), intestines (excrete body wastes, absorb nutrients and immune function)
* Vitamin D deficiency and thyroid disease
* Chronic stress – suppresses the immune system
* Sexual behaviour (e.g. cervical cancer, HIV, etc.)
* Compromised immunity
* Excess alcohol (e.g. for mouth, oesophageal, breast and colorectal)
* Obesity, e.g. breast cancer in post-menopausal women (excess body fat changes hormone metabolism = higher oestrogen = drives oestrogen-positive tumours)
* Excessive exposure to sunlight
* Metal toxins (i.e. aluminium, mercury)
* Medications e.g. immunosuppressant’s, HRT, antibiotics (altering flora and immunity)
* Vaccine ingredients e.g. aluminium, formaldehyde, mercury, human/animal DNA, etc
Dietary Risk factors
- Red meats (esp. for colorectal, prostate, bladder, breast, gastric and pancreatic cancers). Higher risk if charcoal cooked / smoked and at high temperatures
- Burnt food (produces ‘acrylamides’)
- Low fibre – high in photochemicals and clears toxins and hormones such as oestrogen through the bowel
- N-nitroso compounds (e.g. cured meats)
- Refined sugars – feed cancer cells and promote growth (and increase acidity)
- Dairy – pro inflammatory and contains IGFs (insulin-like growth factors) that promote tumour growth
- Table salt, pesticides and aspartame
Cancer and Host Immunity
Chronic immunodeficiency can increase the risk of for cancer
* Cytotoxic T-lymphocytes, natural killer cells and macrophages are needed to destroy abnormal cells
* HIV targets CD4 cells (T-helper cells and macrophages), which, therefore, compromises the host immune system
* Even chronic stress, which would elevate cortisol levels, would suppress the immune system
* A healthy, functioning immune system is essential to providing support against malignant cell development
Benign Tumours
Benign tumours usually consist of differentiated cells which appear similar to normal cells so may be functional.
* Reproduce at a higher rate than normal
* A benign tumour is very often encapsulated = no metastasis
* It grows very slowly and does not spread; systemic effects rarely seen
* Not life-threatening but damage can result from compression of tissues (e.g. brain = raised intracranial pressure)
Malignant Tumours
Usually made of undifferentiated, non-functional cells with varied shapes and sizes and large nuclei
* The cells reproduce much faster than normal
* Not encapsulated = infiltrate other tissues (metastasise)
* Often systemic – can spread very quickly to other organs
* Life-threatening due to tissue destruction and spread of tumour
* Oncology is the study of malignant tumours
Grades
The measure of the degree of cell differentiation / abnormality
* Grade 1; Tumour cells still similar to original. Cells are differentiated and specialized (i.e. benign tumour)
* Grade 4; Tumour cells undifferentiated / many abnormal cells varying in size and shape
Staging
The classification of malignant tumours according to the extent of the disease at the time of diagnosis.
Staging helps to identify treatment approaches, disease progression and prognosis
Basic staging:
* Stage 0: Pre-cancerous cells
* Stage I: Cancer limited to tissue of origin
* Stage II: Limited local spread of cancerous cells
* Stage III: Extensive local and regional spread
* Stage IV: Distant metastasis
