Lecture 1 The Nature of Cancer Flashcards
What is the major risk factor in acquiring cancer
Age – on average the older you are the higher your risk of cancer
The likelihood of developing cancer increases in with age for every cancer T or F
F – the age/incidence prolife varies with different cancer – for example testicular cancer reaches its peak incidence during puberty and adolescence
The incidence of cancer is increasing T or F
T – 80% of patients that die of other causes will be found to have a tumour too
Cancer is a disease where form and function becomes aberrant T or F
T
Explain how the risk factors of various cancers change depending on environment
Melanoma risk is highest and 155x more likely in Australia than its lowest incidence in Japan. Prostate cancer has the highest incidence in the US being 70x more likely that its lowest incidence in China. Finally China has the highest risk of liver cancer with patients 42x more likely to contract it that in Canada where the risk is lowest
Explain the results of the Japanese/Hawaii migrant studies in explaining the environmental influence in cancer influence
Amongst Japanese nationals living in Japan stomach and liver cancer levels were high whilst prostate colon and breast cancer incidences were low. However Caucasian people living in Hawaii had a high incidence of prostate and breast cancer but low levels of stomach cancer. After moving to Hawaii though the rates of both stomach and liver cancer decreased amongst Japanese migrants. However the levels of colon breast and prostate cancer in these migrants did see an increase towards the higher levels seen in Caucasian Hawaiians. This shows that migrants acquire a cancer spectrum depending on their environment not just their genetic heritage
Japanese migrants acquired the cancer profile of Caucasian people upon migration to Hawaii T or F
T
Why were stomach cancer incidence rates particularly high in Japan
The diet consists of large amounts of sea fish and sulphides which have been found to be carcinogenic
Cancer risk is affected by environmental influences T or F
T
Explain Richard Doll’s contribution to cancer research
Doll linked the carcinomas of the lung to smoking. He was deemed the father of epidemiology for correlating of the number of cigarettes smoked to the incidence of lung cancers. He also identified the lag phase after taking up smoking due to the time taken for the induction of genetic instability
How long is the lag phase after taking up smoking before lung carcinomas usually begin to present
20 years in men
Give examples of cancers that have a genetic or familiar basis of inheritance
Colon cancer – FAP/APC Retinoblastoma Kidney Cancer – Wilms’ Tumour Breast Cancer – Hereditary (BRCA1/2)
A single mutation is enough to cause cancer T or F
F
The probability of a change associated with cancer is proportional to age T or F
T
What is the equation that links the probability of tumorigenesis with the number of mutations and age
Log(P)T = nLogA + k where P(T) is the probability of a tumour forming n is the slope or the number of mutations required A is age and k represents a constant
What is the gradient of the cancer incidence against age graph and what does this tell us
The gradient of a log graph of cancer incidence against age gives the number of genetic changes required to cause the disease. This value is around 6 implying that 6 is the number of driver mutations to get cancer
What was the contribution of Katsusaburo Yamagiwa to our understanding of cancer
Yamagiwa applied the extract of coal tar to the ears of rabbits. He noticed that this lead to a dose-dependent induction of carcinoma. This identified a mechanism by which chemicals can cause cancer
What are the 3 conceptual ways in which cancer emerges give an example of each
Chemical (benzo[a]pyrene) physical (radiation) and viral (RSV HPV EBV)
What is the common element in the way in which cancer emerges
Mutagenesis
What are the two mice models of cancer
The Oncomouse is a genetically engineered mouse that will develop tumours. In contrast the Xenograft mouse is a model whereby a nude/immunocompromised mouse is injected with patient-derived tumours. These will induce human cancers in these mice
What is the main benefit of the xenograft mouse cancer model
These cancer in these mice are of human cells so will perhaps more accurately model what is seen in patients
What are some of the issues of animal models in cancer
Issues with the time of onset of the cancers and the nature and behaviours of both the primary and metastatic tumours
List some of the hallmarks of cancer
Sustaining proliferative signalling evading growth suppressors resisting cell death genome instability and mutation avoiding immune destruction enabling replicative immortality and activation of invasion and metastasis
