Carcinogenesis Flashcards
What is carcinogenesis?
-the transformation of normal cells to neoplastic cells through permanent genetic alterations or mutations
-applies to malignant neoplasms
-multistep process
Neoplasm
-abnormal mass of tissue that forms when cells grow & divide excessively or do not die when they should
Oncogenesis
-the transformation of normal cells into cancer cells
-benign & malignant tumours
Carcinogens
-agents known/suspected to cause tumours
-act on DNA (mutagenic)
Carcinogen
Cancer causing - malignant tumour
Oncogenic
Tumour causing
Examples of occupational/behavioural risk factors for cancers - lung, bladder, scrotal
Lung cancer - strong association with cigarette smoking, asbestos
Bladder cancer - increased incidence in aniline dye & rubber industries
Scrotal cancer - increased incidence in chimney sweeps
Name five classes of carcinogens
-chemical
-viral
-ionising & non-ionising radiation
-hormones, parasites, mycotoxins
-miscellaneous
Chemical carcinogens
-no common structural features
-some act directly
-most require metabolic conversion from pro-carcinogens -> ultimate carcinogens (enzyme required may be ubiquitous or confined to certain organs
Ionising & non-ionising radiation
-exposure to UVA/UVB
-ionising radiation
-long term effect (latent interval)
Examples of ionising & non-ionising radiation in cancer
Skin cancer - radiographers
Lung cancer - uranium miners
Thyroid cancer - Ukrainian children
Examples of ionising & non-ionising radiation in cancer
Skin cancer - radiographers
Lung cancer - uranium miners
Thyroid cancer - Ukrainian children
What percentage of cancers are inherited?
15%
Examples of race and cancer incidence
-black people -> more melanin -> decreased skin cancer
-India/SE Asia -> reverse smoking -> increased oral cancer
Ratio of breast cancer in females:males
200:1
What are pre-malignant conditions?
-identifiable local abnormality associated with increased risk of malignancy at that site
Examples of pre-malignant conditions
Colonic polyps
Undescended testis
Cervical dysplasia
What are host factors which can affect cancer risk?
-race
-diet
-constitutional factors - age, gender
-premalignant conditions
-transplacental exposure
Name two inherited predispositions for cancers
FAP
HNPCC
What is FAP?
-familial adenomatous polyposis
-inherited disorder involving the development of benign polyps/adenomas in the colon
-these may develop into cancerous growths
What is HNPCC
-hereditary non-polyposis colon cancer
-condition affecting DNA mismatch repair genes
-increases risk of developing colon cancer
