cancer

• cancer is uncontrolled cell division
• Uncontrolled growth of abnormal cells produces a mass, or tumour
• Malignant means tumour cells are able to spread to other parts of the body, this is known as metastasis. this way, secondary tumours may develop away from the original tumour 
• Benign means tumour cells are not able to invade normal tissues, blood or lymph vessels so do not spread. they can be dangerous if they exert pressure on vital organs (e.g. brain), but are surrounded by capsule and so are easy to remove
• genetics can affect likelihood of developing cancer
• Certain environmental factors called carcinogens can trigger malignant tumours. cancer usually develop after long exposure to carcinogens and can develop years after exposure has ended
• carcinogens :

  • UV radiation
  • X-rays
  • Ionising radiation
  • Viruses
  • Chemical carcinogens
• UV radiation is a part of sunlight and produces cancer of the skin, especially in light-coloured skin. sunburn and overexposure to UV radiation are main causes of skin cancer
• In Australia, x-rays is limited and controlled. radiation produced by modern machines poses little risk to patients 
• Ionising radiation is produced by radium and ores of uranium. a single high does may result in leukaemia. radiation from atomic bombs causes significant increase in cancers 
• Human papilloma virus (HPV) causes cervical cancer. Gardasil vaccine was introduced in Australia in 2007 
• Chemical carcinogens are widespread in modern society. they include, alcohol (excessive consumption), asbestos, soot and tar, organic solvents in glue and paint, tobacco tar. however, simple precautions can be taken to avoid excessive exposure 
• Incidence of cancer has been reduced through education and legislation
• Public has been made aware through advertising and other educational programs of the need to limit exposure to carcinogens. for example Slip! Slop! Slap! Seek! Slide!
• Government has passed laws to control exposure to carcinogens

  • smoking is banned in most public place
  • advertising of tobacco is not permitted
  • cigarettes must be sold in plain packaging with graphic health warnings
  • Standards for manufacture and operation of X-ray machines
  • Products containing asbestos are banned
• Reducing risk of cancer : 

  • Avoid smoking
  • Uses sunscreen, sunglasses etc. to limit exposure to UV 
  • Stay out of direct sunlight 10am - 3pm
  • Ensure diet has adequate fibre
  • Avoid being overweight or obese
  • Limit alcohol intake 
  • Use protective clothing and face mask when handling chemicals like organic solvents or vinyl chlorides
• Cervical cancer is caused by human papillon virus (HPV) which is transmitted through genital skin contact. most infections clear up naturally in about 8-14 months 
• Changes in cells occur before they become cancerous, the Papanicolaou / pap test can be done to detect cells. cells from cervix are collected and smeared on microscope slide. they are then examined for abnormalities. this does not diagnose cancer, but detects early changes in cells that may develop into cancer 
• Cervical Screening Test ever 3-5 years prevents up to 90% of the most common cervical cancers, it is now one of the most preventable and curable of all cancers.
• Breast cancer is the most common type in Australian women, second more common cancer-related death
• there are free breast cancer screening for women 50-74 years old, however women aged 40-49 and 75+ can also take part. Screening is done my mammography, an X-ray of the breasts which produces a mammogram, an X-ray picture. tumours as small as 1cm in diameter can be detected
• bowl cancer is a malignant tumour that develops in the large intestine. it can be treated if diagnosed early, but there are often no symptoms
• anyone aged 50 - 74 years old are invited to take part in screening for bowel cancer. a Faecal occult blood test (FOBT) tests for blood in faeces. it is done at home and mailed to laboratory. the test can detects small amounts of blood not visible to naked eye. Blood could come from polyps or from bowel cancer. Polyps are small growths inside colon or rectum, most bowel cancer develop from polyps. not all polyps become cancerous, but removal of polyps reduce risk of bowel cancer. if FOBT is positive, patients are referred for a colonoscopy, a visual examination of inside large intestine
• there are no screening program in Australia for prostate cancer
• Many prostate cancers grow very slowly and do not require treatment, other forms grow and spread rapidly and are life-threatening. aggressive forms can be cured if diagnosed while still confined to prostate gland. however there are no test to distinguish between them 
• there are three diagnostic methods for prostate cancer

  • Digital rectal examination (DRE)
  • Prostate-specific antigen blood test (PSA)
  • Biopsy

  all have limitations and side effects
• during a DRE, a doctor inserts gloved finger into anus, where it is possible to feel part of the surface of prostate gland. if there is swelling, hardening, irregularities may indicate cancer. however, only part of the prostate can be felt, some irregularities may be beyond reach
• PSA checks blood for particular protein produced by prostate gland, if PSA is rising, it may indicate tumour 
• If DRE or PSA indicate cancer, a biopsy can be performed. a small sample of tissue can be checked for cancer cells. a spring-loaded needle is used and several samples are taken. the procedure is done under general anaesthetic.