1. Etiology of cancer Flashcards
What is the result of malignant tumors?
- imbalances in the controlled process of normal cell division and cell death
- DNA mutations that are not repaired in a normal manner and are passed on to daughter cells without undergoing apoptosis
Etiological factors of cancer
- Environmental effects: 80-90%
- Infections: 5-10%
- Hereditary factors: 5%
What is the premature death rate due to smoking?
- 6 million per year
- 2.1 million due to malignancy
What cancers are related to smoking?
lung, larynx, lip, oral cavity, pharynx, esophagus
Examples of natural carcinogens
- Alfatoxin B1 leads to liver cancer
- Asbestos leads to mesothelioma and lung cancer
Examples of hormonal carcinogens
- Estradiol and Tamoxifen, leading to breast cancer
- Estrogen leading to breast, endometrial and ovarian cancer
IARC classification of carcinogens
- Category 1: proven carcinogens
- Category 2/A: probable carcinogens
- Category 2/B: possible carcinogens
- Category 3: not classifiable as to carcinogenicity
- Category 4: probably not carcinogenic
What are category 1 carcinogens?
- proven carcinogens
- tobacco smoke, asbestos, alcohol, UV, ionizing radiation, air pollution, contraceptives, processed meat
What are Category 2/A carcinogens?
- probable carcinogens
- bitumen, DDT, anabolic steroids, red meat
What are category 2/B carcinogens?
- possible carcinogens
- phobarbital, cloroform, fiberglass, gasoling, diesel oil, carbon black, lead, chrome, nickel
What are category 3 carcinogens?
- not classifiable as to carcinogenicity
- caffeine, tea, PVC, printing inks, magnetic and electric fields, paracetamol, diazepem
What are category 4 carcinogens?
- probably not carcinogenic
- caprolactam
Examples of carcinogenic microorganisms
- Human papillomavirus (6, 11, 16, 18, 31, 33)
- Hepatitis B virus
- Hepatitis C virus
- Human polyomavirus (BK, JC)
- Human herpesvirus (EBV, CMV, KS)
- human immunodeficiency virus (HIV-1)
- Helicobacter pylori
- Schistosoma haematobium and japonicum
Examples of hereditary cancer syndromes
- hereditary breast cancer: BRCA1, BRCA2
- hereditary retinoblastoma: RB1
- Wilms tumor: WT1
- familial adenomatous polyposis: APC
- Lynch syndrom: MLH1, MSH2, MSH6 PMS1, PMS2
- Peutz-Jeghers syndrome: STK11/LKB1
- Ataxia telangiectasia: ATM
- Li-Fraumeni syndrome: TP53
- Multiple endocrine neoplasia: MEN1
- Xeroderma pigmentosum: XPA, XPB, XPC, XPD, XPE
- Von Hippel-Lindau syndrome: VHL
Characteristic tumors of HPV
cervical, anal, bladder, head and neck
Characteristic tumors of HBV
hapatocellular carcinoma
Characteristic tumors of HCV
lymphoma, aplastic anemia, hepatocellular carcinoma
Characteristic tumors of human polyomavirus
childhood neuroblastoma
Characteristic tumors of human herpesvirus
nasopharynx, Burkitt’s lymphoma, lethal midline granuloma, Kaposi sarcoma
Characteristic tumors of HIV
Increased risk of any tumor development as a result of the primary immunosuppression
Characteristic tumors of helicobacter pylori
stomach
Characteristic tumors of Schistosoma haematobium/japonicum
bladder, liver, clorectal, stomach
Characteristic tumors of breast and ovarian cancer syndrome
breast, ovary, prostate, pancreas
Characteristic tumors of hereditary retinoblastoma
retinoblastoma, osteosarcoma
Characteristic tumors of familial adenomatous polyposis
GI, brain, thyroid, retina
Characteristic tumors of Lynch syndrome
nonpolyposis colorectal cancer
Characteristic tumors of Peutz-Jeghers syndrome
GI, breast, ovary, uterine corpus, testicle, pancreas
Characteristic tumors of Ataxia telangiectasia
lymphoma, leukemia, breast, adrenal gland
Characteristic tumors of Li-Fraumeni syndrome
sarcoma, breast, brain, leukemia
Characteristic tumors of multiple endocrine neoplasia
insulinoma, gastrinoma, hypophysis, parathyroid gland
Characteristic tumors of Xeroderma pigmentosum
melanoma, basal cell carcinoma
Characteristic tumors of Von Hippel-Lindau syndrome
clear cell renal cell carcinoma, pheochromocytoma, retinal angioma
Prevalence of sporadic/acquired tumors
> 95%
Prevalence of hereditary tumors
<5%
