Cancer #2 cause of death in the United States
MC CA in women – breast CA
MC cause of CA-related death in women – lung CA
MC CA in men – prostate CA
MC cause of CA-related death in men – lung CA
PET (positron emission tomography) – used to identify metastases; detects fluorodeoxyglucose molecules
Cytotoxic T cells need MHC complex to attack tumor
Natural killer cells can independently attack tumor cells
Tumor antigens are random unless viral-induced tumor
Hyperplasia – increased number of cells
Metaplasia – replacement of one tissue with another (GERD squamous epithelium in esophagus changed to columnar gastric tissue; eg Barrett’s esophagus)
Dysplasia – altered size, shape, and organization (eg Barrett’s dysplasia)
TUMOR MARKERS
CEA – colon CA
AFP – liver CA
CA 19-9 – pancreatic CA
CA 125 – ovarian CA
Beta-HCG – testicular CA, choriocarcinoma
PSA – prostate CA (thought to be the tumor marker with the highest sensitivity, although specificity is low)
NSE – small cell lung CA, neuroblastoma
BRCA I and II – breast CA
Chromogranin A – carcinoid tumor
Ret oncogene – thyroid medullary CA
Half-lives – CEA: 18 days; PSA: 18 days; AFP: 5 days
ONCOGENESIS
Cancer transformation:
1) Heritable alteration in genome and;
2) Loss of growth regulation
Latency period – time between exposure and formation of clinically detectable tumor
• Initiation – carcinogen acts with DNA
• Promotion of cancer cells then occurs
• Progression of cancer cells to clinically detectable tumor
Neoplasms can arise from carcinogenesis (eg smoking), viruses (eg EBV), or immunodeficiency (eg HIV)
Retroviruses contain oncogenes
• Epstein-Barr virus – associated with Burkitt’s lymphoma (8:14 translocation) and nasopharyngeal CA (c-myc)
Proto-oncogenes are human genes with malignant potential
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RADIATION THERAPY (XRT)
M phase – most vulnerable stage of cell cycle for XRT
Most damage done by formation of oxygen radicals → maximal effect with high oxygen levels
Main target is DNA – oxygen radicals and XRT itself damage DNA and other molecules
Higher-energy radiation has skin-preserving effect (maximal ionizing potential not reached until deeper structures)
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