neoplasm 6 Flashcards
describe radiation carcinogenesis
- Skin cancer = basal cell carcinoma, squamous cell carcinoma, MELONOMA
MECHANISM: - pyrimidine dimers –> DNA damage
- normal DNA repair - NER pathway (nucleotide excision repair)
- individuals with enzyme defects mediating DNA repair are particularly susceptible (xeroderma pigmentosum)
describe ionizing radiation
- direct effect
- indirect effect via free radicals
- increased risk with higher dose or high LET
- MECHANISMS = chromosome breakage, translocation and point mutation
define atomic bomb cancers
- normally occurs Leukemias (except CLL)
- also causes Thyroid cancer (papilary type)
- breast/lung cancer (less common)
- Skin, bone, gut are LEAST susceptible
Define X ray workers
- radiation dermatitis
- develop skin cancer
what type of cancer does painting dials of watches with lumnious radium cause
- osteosarcoma
describe teh pathogenesis of hepatitis B in causing cancer
- Chronic liver cell injury and regenerative hyperplasia
- encodes regulatory protein HBx protrein that is responsible for:
- -> activating growth promoting genes (insulin-like GF)
- -> binds to p53 (inhibition)
- causes hepatocellular carcinoma
describe the pathogenesis of hepatitis C in causing cancer
- chronic liver cell injury and regeneration
- causes hepatocellular carcinoma
describe Epstein-Barr virus as it is releated to cancer
- Associated neoplasms
- -> burkitt lymphoma
- -> hodgkin lymphoma
- -> B-cell lymphoma in immunosuppressed patients
- -> nasopharyngeal carcinoma
describe HPV as it is related to cancer
- HPV 6 and 11 = low risk episomal (non-integrated form) –> cause benign squamous papiloma (warts)
- HPV 16,18,31 = high risk; viral DNA integrated in host genome (E6 inhibits p53; E7 inhibits Rb)
describe Human T-cell leukemia virus Type 1 (HTLV-1)
- Causes T-cell leukemia/lymphomas
- Mode of transmission = intercourse, blood, breast feeding
- Pathogenesis = CD4 tropism
- Contains Tax gene:
1) stimulates transcription of viral mRNA
2) activates c-Fos, IL-2(T-cell GF) and FM-CSF = all involved in proliferation
3) inactivates p16INK4a (is an anti-proliferative molecule)
Describe HIV as it is related to cancer
- causes lymphoma
- human herpes virus 8 (HHV-8) causes kaposi sarcoma
- -> associated with HIV
describe how H. Pylori is releated to cancer
- Assocaited with gastric lymphoma (MALT lymphomas), and Gastric carcinoma
- CONTAINS CagA (cytotoxin associated gene A) which stimulates growth factor pathway
describe estrogen
- related to breast cancer, squamous cell carcinoma of cervix and leiomyoma of uterus
how to determine between benign and malignant
- benign have a capsule
describe contraceptive hromoens
- assocaited with breast cancer and benign/malignant liver tumors
describe anabolic steroids
-associated with benign/malignant liver tumors