etiology of cancer review:

Radiation	UV à increased risk cutaneous cancer ·         UVB (280-320), UVC (200-280) = mutagenic ·         UVB à pyrimidine dimmers à repaired by nucleotide excision appartatus o   Xeroderma pigmentosum: defect in ability to repair dimmers o   Excess sun exposure overwhelms pathway
	Ionizing radiation (Xray, Gamma, Particulate) ·         Hematopoietic (Leukemia) >thyroid (young) > solid ·         Skin/bone/GI relatively resistant
Microbial	HPV ·         6,11: low risk for cancer à genital warts ·         16,18 > 31,33,35,51…high risk for cancer (85% invasive sqaumous cell carcinoma of cervix/anogenital region + precursors –dysplasia + CIS) ·         HPV genome integrates into host à cellular instability ·         E6, E7: p53 inactivation (E6), Rb inactivation (E7)
	EBV: ·         Burkitt lymphoma (African) ·         B-cell lymphoma – immunosuppressed ·         Nasopharyngeal carcinoma
	HBV/HCV ·         Hepatocellular carcinoma
	HTLV-1: Human T-cell leukemia virus type 1: ·         T-cell leukemia/lymphoma
	H. pylori: GN bacteria ·         Chronic/atrophic gastritis + duodenal/gastric ulcers ·         Associated with Gastric lymphoma / adenocarcinoma ·         2-6X ↑ risk MALT lymphoma ·         Chronic inflammation + environmental/host factors à atrophic gastritis and metaplasia à dysplasia à cancer ·         May stimulate polyclonal B-cell proliferation via H.Pylori reactive T cells à may aquire mutations à monoclonal lymphoid tumors dependent on T cell stimulation o   Removal of  H.pylori à removal antigenic stimulus for T cells à tumor regression
	HIV: ·         primary CNS lymphoma
	HHV-8 ·         Kaposi sarcoma ·         Body cavity fluid B-cell lymphoma
	Schistosoma Haematobium ·         Squamous cell carcinoma of transitional epithelium **bladder (Egypt)
Chemical	·         Aflatoxins (aspergillus – grains/nuts) àliver: HCC ·         Vinyl Chloride à liver: angiosarcoma ·         CCl4 à liver: centrolobular necrosis / fatty change ·         Arsenic à Skin (squamous cell carcinoma) + Liver (angiosarcoma) ·         Nitrosamines (Smoked foods/perservative) à stomach: Gastric cancer ·         Cigarette smoke (polycyclic aromatic hydrocarbons) à Lung (Sqamous and small cell carcinoma) + Larynx (sqamous cell carcinoma) + kidney (RCC) + bladder (transitional cell carcinoma) ·         Naphthalene (amiline) dyes à bladder : transitional cell carcinoma ·         Asbestos à lung: mesothelioma and bronchogenic carcinoma ·         Alkylating agents à blood: leukemia
Disease conditions associated with cancer	·         Acanthosis nigricans à visceral malignancy ·         Actinic keratosis à squamous cell carcinoma (Skin) ·         Autoimmune disease à lymphoma ·         Barretts esophagus à esophageal adenocarcinoma ·         Chronic atrophic gastiitis/ pernicious anemia à gastric adenocarcinoma ·         Cirrhosis: HCC ·         Downs syndrome à ALL, AML ·         Dysplastic nevus à malignant melanoma ·         Pagets  (bone)à secondary osteosarcoma, fibrosarcoma ·         Plummer-vincent syndrome à squamous cell carcinoma (esophagus) ·         Tuberous sclerosis à astrocytoma, aniomyolipoma, cardiac rhabdomyoma ·         UC à colonic adenocarcinoma ·         Xeroderma pigmentoum / albinism à melanoma, basal cell carcinoma + Squamous cell carcinoma skin