Reference no: EM132277711 , Length: word count:1000

Assignment: The basis of cancer prevalence

This assignment is divided into two sections. The first is to write a summary of the studies done to produce Figure 1 in "Variation in cancer risk among tissues can be explained by the number of cell divisions.", Tomasetti and Vogelstein, Science 347, 78-81. The second part of the assignment is to answer questions about the analysis that produced Figure 2, and the author's interpretation of this figure. Both parts of the assignment can be on a single page that is uploaded to Canvas.

Summary - Your summary should be 1/3 to ½ page in length, single spaced. It should clearly state the objective of the researchers, explain the methods that they used to generate Figure 1 and summarize the conclusions that they arrived at based on this figure.

Questions

1) How do the authors calculate the "extra risk score", or ERS? Why did they decide to generate a number that reflects the lifetime risk and total number of stem cell divisions?

2) Examine two examples in Figure 2, pancreatic islet (adjusted ERS -17.83) and lung, smokers (adjusted ERS 7.61). Note that stem cells in these tissues undergo roughly the same number of divisions. If you were to draw a "best fit" straight line through the points in Figure 1, where would these two examples fall? What does this mean in terms of the relative importance of replicative errors in development of these two types of cancer?

3) In Figure 2 the authors group cancer types into two categories, "deterministic" and "stochastic". What do they conclude about the relative importance of replication errors, inherited mutations and environmental factors in these groups?

4) Briefly summarize why the authors believe that approaches to cancer prevention should be revised.

Attachment:- Assignment File - Vogelstein cancer risk.rar