T24 - General Principles of Tumorigenesis Flashcards
Define tumor.
swelling or mass
Does a tumor imply cancer?
No. The presence of a tumor indicates the possibility of a malignancy, but does not imply cancer.
What is a neoplasm?
biological process of cellular growth in which a group of cells grows faster than its neighbors
How would a neoplasm arise?
if a group of cells acquires somatic (i.e. not inherited) mutations that confer growth advantage
What is a precancer?
microscopic neoplasm that does not yet form a tumor
What is the precursor to cervical cancer?
cervical intraepithelial neoplasia (CIN), a microscopic neoplasm
What is a cancer?
neoplasm/neoplastic process in which cells have acquired ability to spread locally (invasion) or systemically (metastasis)
What is a synonym for cancer?
malignancy
Cells in a healthy liver do not divide very much. Under what conditions would cell proliferation increase in hepatocytes?
a partial resection (partial hepatectomy) would induce remaining hepatocytes to quickly proliferate and regrow the lost part of the organ
In the context of neoplasms, what is disequilibrium?
cell growth exceeds cell death, resulting in progressive (but not necessarily indefinite) growth
Explain why most malignant neoplasms have both increased cell growth and increased cell death. (2)
deregulated cell growth triggers apoptosis, and normal apoptotic checkpoints are only partially affected in cancer
however, rate of cell growth outpaces rate of cell death
What are the two defining features of neoplasia?
disequilibrium (cell growth > cell death)
uncoordinated growth
What is contact inhibition?
a physiological stimulus that places limits on cell growth
Explain the relationship between neoplasia and contact inhibition.
neoplasms are no longer responsive to physiological stimuli such as contact inhibition that place limits on their growth
What is hyperplasia? (2)
overgrowth of tissue in response to stimulus for growth
hyperplasia ends once stimulus ends
What are key differences between hyperplasia and neoplasia?
manner of growth:
hyperplasia = coordinated growth and normal architecture
neoplasia = uncoordinated growth and abnormal architecture
mutations vs. stimuli:
neoplasia = results from genetic mutations that allow it to bypass regulatory mechanisms
hyperplasia = impetus for growth arises externally (not internally)
Describe the relationship between neoplasia and hyperplasia.
hyperplasia provides fertile ground for neoplasia
long-standing hyperplasias can become neoplasia-like (but will have more ordered growth)
some neoplasms depend on stimuli
What is the relationship between neoplasia and metaplasia? (2)
metaplasia is also a fertile ground for neoplasia because of a carcinogenic stimulus or because of associated hyperplasia
Dysplasia refers to
abnormal cytoarchitecture and disarrangement of cells seen microscopically
Most cancers arise from which tissue of the body?
most cancers arise from epithelia
How is dysplasia recognized histologically?
loss of normal, progressive maturational sequence
cellular atypia
loss of normal tissue organization
What is cellular atypia?
atypical appearance of cells in a tissue section
What is the relationship between dysplasia and precancer?
dysplasias are a form of precancer (they can either progress into cancers or not)
What is carcinoma in situ?
lesion that histologically cannot be distinguished from cancer cell, but has not transgressed normal tissue boundaries

