Neoplasia Flashcards
What is a neoplasm
an abnormal mass of tissue usually referred to as a tumor
How to neoplasms develop?
When cells fail to regulate their cell division resulting in growth that exceeds the normal rate of growth of the tissue
Tumors can be divided into
Malignant and Benign
Malignant tumor’s (cancerous)
can invade other tissues and metastasize (spread to remote areas)
have irregular borders
grow rapidly
cells are morphologically and functionally different from normal cells, cells less organized than in parent tissue
have abnormal nuclei
show necrosis
Primary tumor vs secondary tumor
Primary tumor- original tumor
Secondary tumor- grow from metastatic deposits in distant organs
Benign tumor (non-cancerous)
spread to other sites but they become large and put pressure on sensitive regions of the body causing problems
Do not invade beyond the tissue of origin
smooth boundaries
grow relatively slow
cells resemble normal cells of tissue of origin
bland nuclear features
Malignant tumors can either be
carcinomas or sarcoma
Tumorigenesis
process by which a tumor forms
Oncogenesis
development of malignant tumor
Genetic changes within cells can be due to a variety of causes including:
ionizing radiation free radicals chemicals some viruses inherited mutations tobacco smoke alcohol chemotherapy drugs
Four main stages in the development of malignant tumors
Transformation
Growth of transformed cells
Local invasion or infiltration
Metastasis
Proto-oncogenes
essential genes that control normal cellular growth, differentiation and apoptosis
when it becomes an oncogene we say it is activated
Oncogenes
mutated versions of proto-oncogenes resulting in the cell dividing when it should not
an oncogene is a dominant gene where only one mutated allele will produce the effect
These mutations are called gain of function mutations
Activation on proto-oncogenes through
point mutation
translocation (gene product controlled by the wrong promoter)
amplification ( multiple copies of the gene)
Examples of oncogenes
growth factors
growth factor receptors
proteins that promote cell division
anti-apoptotic proteins
Tumor suppressor genes
normal genes that keep cells from overgrowing even when oncogenes are activated. Often called anti-oncogenes
Examples of tumor suppressor genes are
genes that detect or repair damaged DNA
genes involved in promoting apoptosis
How to tumour suppresor genes differ from oncogenes
for there to be an effect both alleles that code for a particular protein need to be mutated.
P53
most frequently altered gene in human cancers. It is also one of the best studied TSDs. It regulates cell cycle and prevents excessive cell growth and therefore functions as a tumor suppressor
Functions of P53
activates DNA repair proteins when DNA is damaged
stops cell cycle while the DNA is being repaired and allows it to continue if the DNA is fixed
initiates apoptosis if the DNA is impossible to repair , killing the cell
Carcinomas
most common type of cancer occurring in humans.
They are malignant tumors of the epithelium and invade the underlying tissues
They have some features of the original tissue but the cells are disorganized and less well formed
Three most common types of carcinomas
adenocarcinoma
squamous cell carcinoma
small cell carcinoma
Numerous factors determine recovery from cancer
- stage
-grade
-tumor subtype
-suitability of the organ for surgical removal of the tumor
presence of receptor molecules for drug treatment
immunosuppression
cachexia (progressive weight loss)
Difference between grade and stage
stage-describes how far the tumor has spread from the tissue of origin
grade- describe how much the tumor has changed from the tissue of origin (morphologically)
