Cancer Bio I Flashcards
What are benign tumors?
Grow locally without invasion
Slow growth
good differentiation
No metastasis
What are malignant tumors?
Invade
Grow fast
Atypical, poor differentiation
Metastasizes
What is an adenoma?
Benign epithelial neoplasm
What is a Lipoma?
Benign mesenchymal neoplasm
What are types of Malignant tumors?
Carcinoma - malignant epithelial neoplasm
Sarcoma - malignant mesenchymal neoplasm
Lymphoma/Leukemia - malignant neoplasm of lymphoid cells
How are tumors classified?
According to biologic behavior and histogenesis or cellular features.
What is hyperplasia?
General term referring to the proliferation of cells within an organ or tissue
Results in enlargement of an organ or in a benign tumor
What is Metaplasia?
An adaptive substitution of one type of adult tissue to another type of adult tissue
Under stress, a more vulnerable type of tissue will be replaced by another more capable of withstanding the stress
What is dysplasia?
An abnormality in cell size, appearance, with or without a disorganized growth pattern
What is neoplasia?
A disease of cells characterized by alteration of normal growth regulatory mechanisms
What is desmoplasia?
The formation and proliferation of connective tissue in response to neoplastic growth
What type of tumors do cells that serve protective function give rise to?
Basal cell carcinoma
Squamous cell carcinoma
What type of tumors do cells that secrete substances give rise to?
Adenocarcinomas
Where do the majority of human tumors arise?
Epithelial tissues
Accounts for 80% of cancer deaths
What causes cancer?
Changes in gene expression due to insults to the genome of a cell usually over an extended period of time
What factors influence individual susceptibility to carcinogenesis?
Age
Hereditary variation in enzymes that either activate or inactivate potential carcinogens
Variations in the efficiency of DNA repair
Gender
Nutrition
What types of tumors are caused by viruses?
Liver cancer - Hepatitis B and C
Cervical carcinoma - Papillomaviruses
Brain tumors
Mesothelioma
What are Simian virus 40 (SV40) and polyomavirus?
Cancer causing viruses that are used as models
How does SV40 cause cancer?
In nonpermissive cells, the early region of the SV40 genome contains proteins that stimulate host cell gene expression and DNA synthesis
What are papillomaviruses?
Small DNA viruses that can cause benign tumors while others cause malignant carcinomas, particularly cervical and anogenital cancers
What genes does cell transformation result from from human DNA viruses?
Expression of two early-region genes, E6 and E7.
What are adenoviruses and by what mechanism do they cause transformation?
Large family of DNA viruses no associated with cancer
Can induce transformation in nonpermissive cells
E1A binds Rb protein, E1B binds p53
What are Kaposi’s sarcoma-associated herpesvirus and Epstein-Barr virus?
Viruses that can cause human cancers
What is Human T-cell lymnphotropic virus (HTLV-1)?
Causative agent of adult T-cell leukemia
What is primary prevention?
Aimed at reducing cancer incidence by avoiding the exposure of individuals to known carcinogens
What is secondary prevention?
Aimed at the early diagnosis of preneoplastic, preinvasive lesions, or early stage cancer in general
What is tertiary prevention?
Aimed at reducing the incidence of recurrence or metastasis
E.g. chemotherapy
What are some symptoms of cancer?
Ulceration and sores that don’t heal
Unexplained weight loss
Unusual bleeding
Presence of a lump in the absence of a primary tumor
What is tumor initiation?
Genetic alterations leading to abnormal proliferation
What are tumor promoters?
Chemicals that are not carcinogenic on their own but enhance oncogenesis through stimulation of cell proliferation
What are the six properties of cancer cells?
Uncontrolled proliferation
Limitless replicateive potential
Insensitivity to antigrowth signals
Evasion of apoptosis
Angiogenesis
Tissue invasion and metastasis
How does cancer cell immortalization occur?
Overexpression of telomerase
Why do cancer cells promote angiogenesis?
Angiogenesis is required as tumor size increases beyond 2mm because they need a supply of nutrients
