Cancer Biology

Comprehensive vocabulary flashcards covering the etiology, cellular mechanics, terminology, staging, spread, and clinical manifestations of cancer biology.

Autonomy

A defining heritable property of cancer cells characterized by excessive, unregulated cellular proliferation and reproduction independent of physiologic controls and signaling from neighboring cells.

Anaplasia

The loss of cellular differentiation in cancerous cells, causing them to lose their specialized functions and fail to die when expected.

Cell Proliferation

The programmed generation of new daughter cells divided from progenitor (parent) cells under genetic control, occurring via mitosis in somatic cells and meiosis in germ cells.

Cell Differentiation

The orderly process of cellular maturation from an adaptable, flexible pluripotent stem cell into an unadaptable unipotent cell with a designated, specialized function.

Neoplasm

A new, uncontrolled growth of cells (tumour) that is not under physiologic control, characterized pathologically by autonomy and anaplasia.

Benign Tumour

A non-cancerous neoplasm that typically grows slowly, exhibits a low mitotic index, is well-differentiated, encapsulated, non-invasive, does not metastasize, and usually does not cause death.

Malignant Tumour

A cancerous neoplasm characterized by rapid growth, a high mitotic index, poor differentiation, an absence of a capsule, local tissue invasion, and the capacity to metastasize and cause death.

Mitotic Index

A clinical measure of cellular proliferation status defined as the ratio between the number of cells undergoing mitosis and the total number of cells in the population.

Meningioma

A benign neoplasm arising from the meninges surrounding the central nervous system that, despite non-malignant histology, can be fatal by physically compressing underlying brain tissue.

Carcinogen

Any substance, radionuclide, or radiation directly involved as an agent in causing genetic mutations that lead to cancer.

Monoclonal Origin Theory

The pathogenic principle stating that cancer originates from the progressive accumulation of multiple mutations within a single transformed cell.

Mutator Genes

Genes encoding proteins that function as cellular "spellcheckers" by identifying and repairing errors and mutations in DNA sequences.

Proto-oncogenes

Normal cellular genes that code for proteins promoting cell growth and division, which become oncogenes driving uncontrolled proliferation when mutated.

Tumour Suppressor Genes

Genes encoding proteins that restrain cell growth, inhibit excessive cell division, and regulate apoptosis, acting as molecular "stop" switches.

p53 Gene

A critical tumour suppressor and mutator gene whose protein initiates DNA repair or stimulates apoptosis when DNA damage is too severe; it is defective or mutated in about half of all human cancers.

Initiation (Carcinogenesis)

The first step of carcinogenesis involving an irreversible genetic alteration or mutation in a cancer-related gene, often caused by exposure to a carcinogen.

Promotion (Carcinogenesis)

The second stage of carcinogenesis requiring continuous exposure to a promoter (mitogen) to stimulate cell division and growth of initiated, mutated cells.

Progression (Carcinogenesis)

The terminal stage of carcinogenesis characterized by autonomous, uninhibited cell proliferation that no longer requires promoter exposure, culminating in a malignant tumour.

Growth Fraction

The percentage of cells within a tumour that are actively dividing at any given time, serving as the main determinant of tumor growth rate and chemotherapy sensitivity.

Pleomorphism

Morphological variability in cellular and nuclear size and shape, often featuring unusually large, bizarrely contoured nuclei with coarse, clumped chromatin.

Aneuploidy

The condition of possessing an abnormal number of chromosomes (too many or too few) resulting from failures at mitotic checkpoints during division.

Carcinoma

A malignant neoplasm arising from epithelial or endothelial tissues.

Sarcoma

A malignant neoplasm arising from mesenchymal (connective) tissues such as bone, cartilage, fat, fibrous tissue, or muscle.

Adenocarcinoma

A malignant epithelial tumour originating specifically from glandular or ductal epithelium.

Angiogenesis

The formation of new blood vessels from pre-existing vasculature, mediated by factors such as VEGF, allowing tumours to grow beyond $1\text{--}2\,mm^3$.

Vascular Endothelial Growth Factor (VEGF)

An angiogenic growth factor upregulated by cancer cells that stimulates endothelial cells to release basement-membrane-degrading proteases and sprout new blood vessels toward the tumour.

Direct Extension

The local infiltration and spread of a malignant neoplasm into adjacent tissues across anatomical boundaries, aided by secreted tissue-degrading enzymes.

Metastasis

The discontinuous spread of tumour cells from a primary anatomical site to a distant, non-adjacent secondary site, serving as the most reliable hallmark of malignancy.

Hematogenous Spread

A mode of metastasis where tumour cells invade blood vessels (principally veins due to thinner walls) and travel to distant capillary beds, typical of sarcomas and renal cell carcinomas.

Seeding (Transcoelomic Spread)

Metastatic dissemination occurring when neoplastic cells detach from an affected organ and implant across body cavities, such as peritoneal, pleural, pericardial, or meningeal spaces.

Seeding the Soil Theory

The hypothesis proposing that metastasizing cancer cells preferentially home to and survive in distant tissues sharing microenvironmental or embryological characteristics with their tissue of origin.

TNM Classification System

An anatomical staging framework that evaluates primary tumour size and extent ($T$), regional lymph node involvement ($N$), and distant metastasis ($M$).

Carcinoma in Situ

An early, localized epithelial neoplasm designated as $T_{is}N_0M_0$ that exhibits neoplastic cellular characteristics without penetrating the basement membrane.

Gleason Grading System

A prostate cancer histological grading system ranging from Grade 1 to Grade 5 that classifies tumours based on architectural cellular differentiation and packing density.

Tumour Markers

Antigens, enzymes, or hormones produced by cancer cells and detected in blood or urine that signal neoplastic presence and help evaluate therapy response.

Cancer Antigen 125 (CA-125)

A transmembrane and secreted mucin protein (MUC16) that mediates peritoneal cell adhesion and functions as a clinical tumour marker for ovarian, lung, breast, and pancreatic cancers.

Prostate Specific Antigen (PSA)

A protein (gamma-seminoprotein) normally restricted to seminal fluid that serves as a blood-based tumour marker for anaplastic prostate cancer.

Carcinoembryonic Antigen (CEA)

An oncofetal protein normally manufactured during fetal gastrointestinal development whose presence in postnatal circulation signals anaplastic carcinomas of the colon, lung, stomach, pancreas, or breast.

Cachexia

A multifactorial wasting syndrome characterized by progressive weight loss and depletion of muscle and adipose tissue, mediated in part by tumour-induced cytokines like TNF and interleukin-1.

Deep Vein Thrombosis (DVT)

Thrombus formation within deep veins (commonly in the lower extremity), elevated in cancer patients due to tumour release of thromboplastin, HIF-1, EGR-1, and inflammatory cytokines.

Paraneoplastic Syndromes

Systemic symptom complexes caused by ectopic hormone/cytokine secretion by tumor cells or aberrant immune cross-reactivity, rather than by direct local invasion or metastasis.

Trousseau Syndrome

A paraneoplastic hypercoagulable state manifesting as recurrent, unexplained venous thrombotic events, often serving as an early indicator of occult gastric or pancreatic adenocarcinoma.

Carcinoid Syndrome

A paraneoplastic syndrome caused by hypersecretion of serotonin and 5-hydroxy-indoleacetic acid ($5\text{-}\text{HIAA}$) from metastatic carcinoid tumours, causing flushing, diarrhea, and bronchoconstriction.