Question

71

Once a neoplasm has been established, all of the following are required for progression to metastatic disease EXCEPT:

Select one:

A. Apoptosis.

B. Angiogenesis.

C. Detachment and invasion.

D. Spread via lymphatic and blood vessels.

Answer 1

Ans. Once a neoplasm has been established, apoptosis is not required for progression to metastatic disease.

Explanation ---

Apoptosis is also known as programmed cell death. Apoptosis is an important function of the body and it eliminates unwanted cells during early development. It also plays an important role in preventing cancer by maintaining the balance of cells in the human body. So it doesn't play any role in the progression of metastatic disease and in the contrary it is against the formation of neoplasm.

B. Angiogenesis ---

Angiogenesis is the development of new blood vessels to support the growth of tissues. It is a normal part of growth and healing in the body. But it also plays a role in several diseases, including metastatic disease. It is required for progression to metastatic disease because a tumor needs nutrients and oxygen to grow and spread, and it is being fulfilled by angiogenesis.

C. Detachment and invasion ---

Detachment means separation, and invasion means the movement of cells.

Both are required in progression to metastatic disease because, in metastasis, detachment of cancer cells from their parent tumor is an initial early event in metastasis and by invasion, the cancer cells directly penetrate into surrounding or neighboring tissue leading to an acceleration in the progression.

D. Spread via lymphatic and blood vessels ---

This is an important step for the progression of tumor cells to lymphatic and blood vessels. The spread of tumor cells into lymphatic and blood vessels occurs as, tumor cells secrets enzyme MMP( matrix metallopeptidase) which degrades the collagenous extracellular matrix, breaking through the basement membrane that surrounds the tumor cells to migrate towards the blood or lymph vessels. When the MMPs reach the vessels they breakdown the basement membrane surrounding the vessels through enzymatic action, opening access to epithelial cells lining the vessel. Tumor cells can then migrate into the blood and lymph by entering through the tight junction of epithelial cells. The tumor cells are then transported through the blood and lymph to other tissues.

And now the tumour cells will spread via lymphatic and blood vessels to target some organs and cause further progression.

All of the above 3 discussed options contribute towards progression to metastatic disease except option A. So the answer is option A.