Write a 350- to 525-word essay addressing the following points:
•In your own words, describe how cancer occurs in human cells.
•What changes take place and how does a normal cell progress to a cancerous cell?
•Given what you have learned about cancer, propose an explanation to explain why cancer can be difficult to treat.
•After all the years of research, why don't we have a viable cure for all cancers?
Cite all references in APA format.