Introduction to tumour biology Flashcards
What is cell proliferation?
Cell proliferation is basically the same thing as cell division. It is the multiplication of identical cells.
What is cell differentiation?
Cell differentiation is the process whereby an undifferentiated cells eg a stem cell, obtains the properties of a specialized cell.
This requires the inactivation of proliferation genes and the activation of specific function genes.
What is de-differentiation?
De-differentiation involves the regression of a specialised cell to an unspecialized form (eg back to a stem cell).
This is more commonly seen in simpler life forms such as worms and amphibians rather than humans.
Some disorders of growth are irreversible whereas some are irreversible, give examples of both? HINT: calluses at gym
Reversible - normally due to environment/hormones
eg: doing weights at gym and you get growth of cells on your hands to form calluses. If you stop doing the exercises then your skin will revert back to normal.
Irreversible - these disorders of growth are due to changes in the DNA (mutations) which are inherited in the daughter cells when dividing.
eg: dysplasia, neoplasia).
In terms of the reduction in size of a tissues mass, what do the following concepts mean?
Agenesis
Hypoplasia
Atrophy
Agenesis = total abscence of a tissue to form
(think Asexual - there is a complete lack of a gene giving sexual attraction)
Hypoplasia = an incomplete formation of a structure or organ resulting in it being smaller than normal. This is congenital as apposed to atrophy which is aquired.
Atrophy = basically when cells “waste away” - an aquired reduction in size. eg: when a leg is in a cast there is muscle atrophy and when an organ is starved of blood supply there is shrinkage of the organ
What is hypertrophy?
The enlargement of an organ or tissue as a result of enlargement of its cells.
What is hyperplasia?
The enlargement of an organ or tissue as a result in the number of cells (increase in the reproduction rate of cells).
Note: In some cases this is pre-malignant. There is hyperplasia with atypia (cells that are abnormal) and this is precancerous, but hyperplasia without atypia (proliferaiton of normal cells) is not precancerous
What is metaplasia?
Metaplasia is where there is a reversible replacement of one differentiated cell type with another mature differentiated cell type. This may be part of a normal maturation process or an abnormal response to a stimulus/environment eg epithelium of the esophagus in response to chronic acid reflux.
Note: In some cases this is pre-malignant.
Eg chronic acid reflex disease - metaplasia of stratified squamous esophagus cells to simple columnar gastric cells is abnormal and pre-malignant.
Eg Squmaous metaplasia in the cervix is normal and not pre-malignant
What is dysplasia?
Dysplasia is the enlargement of an organ or tissue by the proliferation of cells of an abnormal type, as a developmental disorder or an early stage in the development of cancer
Note: this is ALWAYS pre malignant. This dosent mean all cases will transform into cancer but its means all tissues that undergo dysplasia have an INCREASED chance of cancer
An example is the formation of keratosis after excesive UV exposure. If not removed this will develop into squamous cell carcinoma of the skin.
An actinic keratosis, also known as a solar keratosis, is a scaly or crusty growth (lesion). It most often appears on the bald scalp, face, ears, lips, backs of the hands and forearms, shoulders, neck or any other areas of the body frequently exposed to the sun.
What are the three grades of dysplasia?
Mild
Moderate
Severe (carcinoma in situ)
Carcinoma in situ also called neoplasm in situ is where the “cancer” has stayed in the place where it began and has not spread to neighboring tissues. There is controversy over whether this should actually be called cancer.
What is neoplasm/ neoplasia?
The term neoplasm refers to an abnormal growth of tissue caused by the rapid division of cells that have undergone some form of mutation.
Neoplasia describes when these cells proliferate in an abnormal manner that is not coordinated with the surrounding tissue. These rogue cells (neoplastic cells) cannot be controlled in the way that normal cells can because they do not die when they should and they divide more quickly. As this excessive growth persists, a lump or tumor that has no purpose or function in the body is eventually formed. This is referred to as a neoplasm and it may be non-cancerous (benign), pre-cancerous (pre-malignant) or cancerous (malignant).
What does it mean by all dysplastic cells are clonal?
This means they have originated from the same original cell.
What is reactive atypia?
This is the presence of immature cells formed in the process of healing or regrowth of the squamous epithelium) eg repair of ulceration.
Note: This is normal and not pre malignant.
What are the main differences between benign and malignant neoplams (tumours)?
Benign =
easily removed, do not spread to other areas (dont metastasize), the cells are differentiated and they have exspansile growth
Malignant =
Cancerous growths that are fatal if left untreated. The cells grow rapidly and have infiltrative growth (invade nearby tissue and spread into other areas of the body). Hence most malignant neoplams will metastasize (spread into other organs) to form secondary cancer.
Note: secondary cancer is still given the name of the primary cancer. Eg pancreatic cancer that has spread to the liver is still called pancreatic cancer.
Note: neoplasm or neoplastic growth of cells forms a mass - a tumour.
Just cos
