BIOL 207 Biology of Cancer August 29, 2007 Lecture 1: What is cancer? Reading: Chap. 1 Kleinsmith pp. 1-12 Outline: 1. Defining cancer 2. Many diseases 3. Normal vs. abnormal cells 4. Benign vs. malignant tumors 5. How cancers vary 6. Cancer diagnosis/staging In your lifetimes, between 1 in 2 and 1 in 3 persons will be diagnosed with cancer. Cancer—“crab”—family of diseases in which tissues grow and spread throughout the body. Disease has been around for thousands of years, but prevalence steadily increasing as humans live longer. Fig. 1-1 Relative frequencies of cancer cases. What does pie chart say? Most common cancer: skin cancer Also common: prostate, breast, lung, colorectal cancers Relative frequency of cancer deaths: Deadliest cancer is lung cancer, followed by colorectal cancer and breast cancer. Skin cancer makes up a small fraction of cancer deaths. Pancreatic cancer makes up a small fraction of cancer cases, but is one of the deadliest cancers. Different regions of the world have different cancer incidences. To make comparisons between death rates, these are adjusted per 100,000/year Different cancers have different death rates; death rate trends may change over time. Fig. 1-2 Describe the trends. Death rate due to lung cancer increased between 1930 and 1990, now declining slightly. Scientists look for factors affecting trends Lung cancer increases with increased smoking and passage of time. Describe the trend in breast cancer death rates. Describe the trend in stomach cancer death rates. 1 Biology of Cancer text The author, Dr. Lewis Kleinsmith, is a professor in cell and molecular biology at the University of Michigan. His focus is on the underlying science behind cancer and what is going on in the cells. Cancer cells have two properties Cell proliferate out of control Cancer cells spread throughout the body (metastasis) Cells are the basic units of life. Levels of organization: Cells tissues organs organ systems individual Initial stages of cancer deal with cells and tissues Later stages deal with spread of cells via organ systems (circulatory, lymphatic) Normal growth vs. abnormal growth of tissues Hypertrophy—increase in cell size i.e. weight trainingmuscles Hyperplasia—increase in cell number i.e. calluseswriting Dysplasia—disorganized growth Neoplasia—disorganized growth, increase in # of dividing cells Fig. 1-4 Normal and neoplastic growth of skin Normal skin: only basal cells divide; other cells migrate and differentiate Skin tumor: cell division occurs among more cell types in several layers; lacks needed specialized cells Benign tumors—grow in a confined area Malignant tumors—can invade surrounding tissues, enter bloodstream, spread to different parts of the body by metastasis A cancer is any malignant tumor. Cancers vary in their site of origin. Lung vs. liver cancer Cancers vary in the cell type of origin Carcinoma vs. sarcoma vs. leukemia epithelia muscle blood 90% 1% 9% of all human cancers 2 Leukemia—cancer of circulating blood Lymphoma—solid tumor containing many blood cells Table 1-2 Naming tumors Cancers vary in their survival rates. Table 1-3; Fig. 1-6 ~99% of patients survive 5 yrs with skin cancer ~20% of patients survive 5 yrs with lung cancer Cancer diagnosis Remove tissue—biopsy Pathologist examines for tumor under microscope Looks for evidence of malignancy Table 1-4 Microscopic difference benign vs. malignant tumors Pathologist “grades” the tumor based on differences in size, microscopic appearance and evidence of metastasis Grade 1: benign tumors grade 4 metastatic tumors Tumors can also be categorized based on their clinical stage. In staging, the estimated progression of a person’s cancer is correlated with prospects for successful treatment. TNM system T = tumor size N =lymph node M = metastasis (1) How large is the tumor and how far has it invaded into surrounding tissues? (2) Are lymph nodes positive for cancer cells (have cancer cells spread to regional lymph nodes? (3) To what extent have cancer cells metastasized to other organs? Lower combined TNM# --cancer detected early and hasn’t spread Higher combined TNM#--more difficult to treat successfully Example: Staging of colon and rectum cancer Classification Tis T1 T2 T3 Description Carcinoma in situ Invasion into submucosa layer of colon wall Invasion into submucosa into underlying muscular layer Invasion through muscular layer 3 T4 N0 N1 N2 N3 M0 M1 Invasion into peritoneal cavity and adjacent organs Regional lymph nodes free of tumor 1-3 positive nodes 4 or more positive nodes Positive nodes on named vascular trunk No distant metastases Distant metastases present Proper staging is critical to proper diagnosis and treatment TNM stage T1N0M0 T4N0M0 T4N1M0 Five year survival rate >90% 60-70% 40% 4 Treatment surgery surgery surgery and chemo or radiation