Lecture Outline - Chapter 21

21.1 Causes and Prevention of Cancer (p. 438)
	1.	A mutagen is an agent that enhances the chance of a DNA mutation. A carcinogen is an environmental agent that can trigger cancer. Carcinogens are frequently mutagenic.
	2.	Carcinogens (p. 438)
		a.	Radiation (p. 438)
			i.	Ultraviolet radiation in sunlight and tanning lamps triggers the development of skin cancers. Melanoma is the spreading form of skin cancer.
			ii.	Radon gas can lead to lung cancer.
			iii.	X rays and nuclear radiation can lead to cancer.
		b.	Organic Chemicals (p. 438, Table 21.1, Fig. 21.2)
			i.	Tobacco smoke contains numerous carcinogens that can lead to cancers of the lung, mouth, larynx, bladder, kidney, and pancreas. 
			ii.	Foods rich in saturated fats and low in fiber are correlated with increased cancer rates for the colon, rectum, and prostate. Certain food additives may be carcinogenic.
			iii.	Pollutants, industrial chemicals, pesticides, and herbicides are mutagenic and can lead to cancer.
			iv.	Viruses have been linked to liver cancer, cervical cancer, a form of lymphoma, and nasopharyngeal cancer.
 				HEALTH FOCUS: Prevention of Cancer (p. 439)
				i.	Protective behaviors include not smoking or sunbathing, avoiding alcohol and radiation, being tested for cancer, and being aware of environmental hazards and hormone therapy.
				ii.	Dietary guidelines for preventing cancer include eating the right diet, which is low in fat, high in fiber and vitamins A and C, low in salt- or nitrate-cured foods, high in cabbage family vegetables, and low in alcohol. Obesity should be avoided.
	3.	Heredity (p. 440)
		Certain cancers, such as breast, lung, and colon cancers, run in families. Some childhood 	 cancers are inherited as a dominant gene.
	4.	Immunodeficiencies (p. 440, Fig. 21.3)
		a.	Certain cancers (Kaposi's sarcoma) are more prevalent in immune-compromised people, such as those with AIDS or on immunosuppressive drugs.
		b.	Cancer development is a multistep process involving initiation, promotion, and progression.
21.2 Cancer Cells (p. 442)
	1.	Characteristics of Cancer Cells (p. 442, Table 21.2)
		a.	Cancer Cells Lack Differentiation (p. 442, Fig. 21.4)
			Cancer cells are not specialized and lack differentiation. Unlike normal cells, they can undergo a limitless number of cell divisions.
		b.	Cancer Cells Have Abnormal Nuclei (p. 442)
			Nuclei of cancer cells are enlarged and can have abnormal numbers of chromosomes. Gene amplification is more common in cancer cells.
		c.	Cancer Cells Form Tumors (p. 442)
			Normal cells exhibit contact inhibition, but cancer cells do not have this restraint. Instead, they produce an abnormal mass, or tumor. Benign tumors do not spread.
		d.	Cancer Cells Undergo Angiogenesis and Metastasis (p. 442, Table 21.2)
			i.	Angiogenesis is needed to help cancerous tumors continue to grow. Cancer cells release growth factors that promote this.
			ii.	Cancer cells tend to be motile and produce enzymes that allow them to dissolve basement membranes and invade surrounding tissues.
			iii.	Prognosis depends on whether the tumor has spread to surrounding tissues, whether there is lymph node involvement, and whether distant tumors have begun (Fig. 21.5).
	2.	Classification of Cancers (p. 443)
		a.	Cancers are classified according to the type of tissue from which they arise.
		b.	Carcinomas arise in epithelial tissues.
		c.	Sarcomas arise in connective tissues, like muscle and bone.
		d.	Leukemias are cancers of the blood.
		e.	Lymphomas are tumors of lymphoid tissues.
		f.	The TNM system is useful in determining the nature of cancer therapy.
21.3 Oncogenes and Tumor-Suppressor Genes (p. 444, Fig. 21.6)
	1.	A series of factors in the growth control network regulate cell growth and reproduction.
	2.	Proto-oncogenes and Oncogenes (p. 444)
		a.	Proto-oncogenes are genes that code for normal growth proteins. Some code for growth factors, others for growth factor receptors, and still others for stimulatory proteins.
		b.	When a proto-oncogene mutates, it becomes an oncogene that brings about uncontrolled cell division.
		c.	The ras family of oncogenes has been implicated in lung, colon, and pancreatic cancers, and in leukemias and lymphomas.
	3.	Tumor-Suppressor Genes (p. 445)
		a.	Tumor-suppressor genes code for growth proteins that stop stimulatory reactions so cell division does not occur. These genes can turn off oncogenes unless they, themselves, mutate.
		b.	Tumor-suppressor gene malfunction (mutation) has been implicated in breast, prostate, and bladder cancers.
21.4 Diagnosis and Treatment (p. 446)
	1.	Diagnosis of Cancer (p. 446)
		a.	The seven warning signs of cancer spell the word CAUTION (see p. 446). 
		b.	Routine Screening Tests (p. 446, Fig. 21.7)
			i.	Pap smears for cervical cancer are an example of a routine screening test. For breast cancer, routine self-exam, exam by a doctor, and mammography are recommended. Colon cancer screening involves a digital rectal exam, sigmoidoscopy, a fecal occult blood test, and colonoscopy. 
			ii.	Blood tests and urinalysis can detect leukemia and bladder cancer.
		c.	Tumor Marker Tests (p. 446)
			Blood tests for tumor antigens/antibodies produced against tumors are called tumor marker tests. They can be used to detect first-time cancer and cancer relapses.
		d.	Tests for Cancer Genes (p. 447)
			When individuals test positive for the presence of marker genes, such as the ras gene for colon cancer and the BRCA1 breast cancer oncogene, they should be vigilant for signs of cancer.
			HEALTH FOCUS: Shower Check for Cancer (p. 447, Figs. 21A-C)
			This Health Focus details how to easily perform a the shower check for breast cancer and testicular cancer. 
		e.	Confirming the Diagnosis (p. 448, Fig. 21.8)
			i.	Surgical or needle biopsies, can confirm the presence of cancer.
			ii.	A number of imaging techniques (CAT scan, MRI, radioactive scans, ultrasound) can confirm a tumor.
	2.	Treatment of Cancer (p. 448)
		a.	Surgery is sufficient for cancer in situ.
		b.	Surgery followed by radiation is recommended when cancer cells may have been left behind.
		c.	Some cancers (cervix, early prostate, larynx, and Hodgkin's disease) can be treated successfully with radiation alone.
		d.	Chemotherapy is used for metastatic cancers that may have spread throughout the body. Chemotherapeutic drugs kill cells during cell division. 
		e.	Other Current Forms of Therapy (p. 449, Fig. 21.9)
			i.	Antihormone therapy is used for cancers that are enhanced by hormones the body produces.
			ii.	Bone marrow transplants are used after the patient has received high doses of chemotherapy and radiation in combination. Bone marrow is needed to replace the blood-forming tissues destroyed by the treatment.
		f.	Future Forms of Therapy (p. 450)
			i.	Immunotherapy (turning on the body's immune system to attack cancer cells) has promise but has yet to be highly effective. The use of monoclonal antibodies designed to combine with receptors on cancer cells is under investigation.
			ii.	Turning off angiogenesis using antiangiogenic drugs confines tumors. These drugs are currently being tested.