DEFINITION, NOMENCLATURE AND EPIDEMIOLOGY

What is neoplasia?

A new growth; an abnormal mass of tissue whose growth exceeds and is uncoordinated with normal tissues, persisting after the stimulus is removed.

What causes neoplasia?

Genetic alterations passed to progeny of tumor cells, enabling excessive and unregulated proliferation.

What are the two broad classifications of tumors?

Benign and malignant.

Give examples of benign mesenchymal tumors.

Fibroma (fibrous tissue), Chondroma (cartilage).

How are benign tumors classified?

By cell of origin, microscopic pattern, and macroscopic architecture.

What is an adenoma?

A benign epithelial neoplasm from glands.

What is a papilloma?

A benign tumor with finger-like or warty projections.

What is a cystadenoma?

A large cystic mass, often in the ovary; if papillary protrusions are present, it is a papillary cystadenoma.

What are sarcomas?

Malignant tumors from mesenchymal tissue, e.g., fibrosarcoma, chondrosarcoma.

What are carcinomas?

Malignant neoplasms from epithelial cells arising from any germ layer.

How do benign and malignant tumors differ in differentiation?

Benign are well-differentiated; malignant are poorly differentiated (anaplastic).

How do they differ in growth rate?

Benign grow slowly; malignant have erratic growth, may be rapid.

How do they differ in local invasion?

Benign are expansile and non-invasive; malignant invade and infiltrate surrounding tissue.

How do they differ in metastasis?

Benign do not metastasize; malignant often metastasize.

What are teratomas?

Tumors from totipotent cells (e.g., ovary, testis) containing multiple tissue types.

When is a teratoma benign?

When mature (well-differentiated).

When is a teratoma malignant?

When immature or overtly malignant.

Give examples of nomenclature for mesenchymal tumors.

Fibroma → fibrosarcoma; lipoma → liposarcoma; osteoma → osteogenic sarcoma.

What is leiomyoma?

Benign smooth muscle tumor.

What is leiomyosarcoma?

Malignant smooth muscle tumor.

What is pleomorphism?

Variation in size and shape of cells in anaplastic tumors.

What is hyperchromatism?

Dark-staining, dense chromatin in nuclei.

What is the nuclear-cytoplasmic ratio in anaplastic cells?

Approximately 1:1.

What indicates high proliferative activity in tumors?

Numerous abnormal mitoses.

What is loss of polarity in cancer cells?

Disorganized cell arrangement and orientation.

What is epidemiology in cancer?

Study of causal links between etiologic agents and cancer occurrence.

Give an example of an etiologic agent and cancer.

Smoking → lung cancer.

What genetic mutations are linked to breast and ovarian cancer?

BRCA1 and BRCA2.

What mutation is associated with melanoma?

p16 tumor suppressor gene mutation.

Name childhood tumors common at ages 0–4.

Retinoblastoma, neuroblastoma, Wilms tumor, hepatoblastoma, leukemias.

What environmental exposure causes mesothelioma?

Asbestos.

What is a pre-neoplastic disorder?

A condition predisposing to tumor formation, e.g., HBV cirrhosis → hepatocellular carcinoma.

What are cancer genes?

Mutated or altered genes causing uncontrolled cell growth.

What are oncogenes?

Mutated proto-oncogenes that cause uncontrolled cell growth when activated.

What are tumor suppressor genes?

Genes that regulate cell growth; when inactivated, lead to uncontrolled growth.

Give an example of a tumor suppressor gene and its associated cancer.

RB gene → retinoblastoma, osteosarcoma.

What happens in defective DNA repair syndromes?

Genetic instability leading to cancer susceptibility.

Give examples of defective DNA repair diseases.

Xeroderma pigmentosum, ataxia telangiectasia, Bloom syndrome.

What are familial cancers?

Cancers occurring in close relatives, often at early onset and with specific markers.

Give examples of familial cancers.

Colon, breast, ovary, brain, melanoma, lymphomas.

What is carcinogenesis?

Multi-step process at phenotypic and genetic levels leading to cancer via accumulated mutations.

What is tumor progression?

Increase in malignancy through multiple mutations creating heterogeneous subclones.

What are the main stages of carcinogenesis?

Initiation, promotion, progression.

What are direct-acting carcinogens?

Compounds that do not require metabolic activation to cause DNA damage.

What are indirect-acting carcinogens?

Pro-carcinogens requiring metabolic conversion to become active.

What occurs during promotion in carcinogenesis?

Proliferation and clonal expansion of initiated cells.

What occurs during progression in carcinogenesis?

Irreversible changes leading to genetic instability and malignancy.