Development of a tumor from a benign form to a malignant from is dependent upon?

Question

A Growth of blood vessels into the tumor

B groth of the tumor

C movement of tumor cells from the original location to another part of the body

D Lack of function of the cells in the tumor

E disorganization of the tissue of the tumor

Answer 1

c - a process known as metastasis

Answer 2

Hello - The answer is C.  

The ability of a cancer cell to move to a new location in the body is what characterizes its malignancy.  

A tumor, in this question, refers to a neoplasm (a new growth of cells), which is commonly defined as a group/collection of cells in a tissue which are behaving/growing in a dissimilar manner to the cells in the rest of the tissue.  This is usually attributable to some form of somatic mutation in the genome of these atypical cells, that allows them to act in this dysregulated manner.

It is important to note that a tumor (neoplasm) can be comprised of benign or malignant cells.  Indeed, most often a cancer will begin as a primary tumor in some location of the body, and within that population of rapidly growing cells (with equally rapid cell turnover rates) a malignant cell will be formed.  This cell will be able to translocate to another region of the body, where it can form another tumor (a secondary tumor).  This is the process of metastasis.

I'll give a brief explanation as to why the other answers aren't appropriate.

A Growth of blood vessels into the tumor

This is important for sustaining the cells near the centre of the tumor.  New vessels grow into a tumor by the process of angiogenesis and supply oxygen and nutrition for the core of the tumor.  Interestingly, these new vessels are visible on the outside of a tumor, where they have a crab-like appearance. It was this observation that lead to the disease being named 'cancer.'  'Cancer' is latin for 'crab' (which explains why the crab star-sign is called 'cancer' in astrology).  

However, new blood vessels or not, the inner depths of a tumor are never well-oxygenated and cells are dying, or are starved for oxygen, in the core region all the time.  This means that the inside of a tumor is rather anoxic (without oxygen), and these are good conditions for inducing high levels of 'metabolic stress' in the benign cancer cells, and is most certainly a key factor in causing further somatic mutations that will lead to malignancy.

Therefore, the growth of new vessels is both important for keeping the benign tumor cells alive but because malignancy can, in some situations, be derived from a population of anoxic cells in the core of a tumor, new vessel formation is not key to defining the crossover from benign to malignant.

B growth of the tumor

By definition, a tumor is a group of cells that are growing in a manner that is atypical to the surrounding tissue.  It doesn't matter if the cells are malignant or benign.  Both can grow uncontrollably.  The crossover form benign to malignant requires further somatic mutation(s), and this process will be hastened if there is a high rate of cell division.  So a rapidly growing tumor might increase the probability of its becoming malignant, but the growth of the tumor itself, is not the key mechanism to forming a malignant cell.  It might be that the tumor grows too fast for new blood vessels to form at an adequate rate, so the cells in the tumor become anoxic and this leads to malignancy-causing mutations, as discussed above).

***C movement of tumor cells from the original location to another part of the body.--

This is the correct answer. Regardless of the mechanism (there are an endless number of possible mechanisms), a cancer cell becomes 'malignant' the instant it can translocate to another location in the body.  This marks an important transformation in several signalling pathways within the cell (primarily, the loss of 'contact inhibition' and 'Anoikis' - note: anoikis is a greek term for 'homeless', and a healthy cell will undergo the process of anoikis whenever it is removed from its normal place of residence/tissue.  Upon eviction from its normal surroundings, the healthy cell undergoes programmed cell death, otherwise known as 'apoptosis' and because the whole process is stimulated by the cell's removal from its normal 'home', it is called 'anoikis').

D Lack of function of the cells in the tumor

this is not specific enough.  Malignancy can be viewed as a benign cell losing the 'anoikis function', but it can also be considered a 'gain of function' to be able to translocate successfully.  Further more, despite the 'faulty' processes in cancer cells, they still require lots of normal functions to be working, just as healthy cells do.  This answer is too vague.

E disorganization of the tissue of the tumor

Generally speaking, the 'more' malignant the tumor, the more disorganized the tissue of the tumor will be.  But this is a result of the tumor, not a cause of it.  Highly cancerous cells will become increasingly amorphous as the population of cancer cells become more and more heterogeneous (the cells become increasingly dissimilar as they accumulate damage).  So E is also incorrect.  Tissue (dis)organization is a result of cancer, not a cause.

Hope this helps,

All the Best - Jim

Answer 3

A - Growth of blood vessels into the tumor - angiogenesis

http://math.lanl.gov/~yi/tumor.html

N.B A tumor is already malignant for "C" to happen.