1) Horace Jones had a colonoscopy shortly after his 50th birthday, and the gastroenterologist noticed an unusual mass of tissue in the region of the sigmoid colon. Subsequent tests and surgery revealed that the mass was malignant, having invaded the submucosal and muscularis layers of the colon. Biopsy of regional lymph nodes was positive, with 2 nodes showing tumor cells.
a. What kind of cancer does Mr. Jones have, and what Stage is his cancer?
b. If you looked at a tissue slide, what are the likely differences in appearance between tumor cells from his cancer and normal cells from other parts of the colon?

2) In general, a change in a single allele of an oncogene can result in tumor growth or cancer, while it takes two changes in both alleles of tumor suppressor genes.
a. How do you explain this difference?
b.What do these genes code for normally? That is, in a healthy person, what role are the oncogenes and tumor suppressor genes playing, and how do they do it? 

3) Hepatitis B, Human Papilloma Virus, Epstein-Barr Virus, and Kaposi sarcoma-associated herpesvirus are all associated with cancer, and are all DNA viruses.
a. Are these two facts incidental, or does one help explain the other?
b. Another virus associated with cancer is HTLV (Human T cell leukemia-lymphoma virus), which is a retrovirus. How does this relate to the DNA viruses in the list?
c.Why do only a small fraction of those infected with one of these viruses develop cancer?