Saturday, February 11, 2012

Pancreatic cancer: 20 years to grow into detectable tumors


Pancreatic Cancer Growth Mechanism

The human body is made up of myriads of living cells, the building blocks that make up tissues. Normal body cells grow, divide, and die in an orderly fashion. During the early years of a person's life, normal cells divide faster, giving the person opportunity to grow, while for adult person, most cells divide only per demand - to replace worn-out or dying cells or to repair injuries.

Pancreatic cancer begins when cells associated with pancreas start to grow out of control. Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells. Cancer cells can also invade (grow into) other tissues, something that normal cells cannot do. Growing out of control and invading other tissues converts a normal cell into a cancer cell.

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Cells become cancer cells because of damage to DNA, which controls each cell functions. In a normal cell, when DNA gets damaged the cell either manages to repair the damage or it dies. In cancer cells, the damaged DNA cannot be repaired, but the cell doesn't die like as it supposes to. Instead, this cell goes on making new cells that the body does not need. These new cells will all have the same damaged DNA as the first cell does.  The buildup of extra cells often forms a mass of tissue called a growth or tumor.

Cancer cells may travel to other parts of the body, where they begin to grow and form new tumors that replace normal tissue. This process is called metastasis. It happens when the cancer cells get into the bloodstream or lymph vessels of our body. 

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Two Types of Cell Changes

A recent 2010 study from Karolinska Institutet shows how two types of cell change interact in the development of cancer. The results can improve the chances of early discovery of pancreatic cancer, where the early detection is especially challenging. Cancer of the pancreas is a form of cancer that has few treatment options and a poor prognosis. It is linked to two particularly common cellular changes: mutations in a family of cancer genes called RAS and increased activity in the 'Hedgehog' signalling pathway, a molecular signal transmission mechanism that is normally only activated during embryonic growth.

Study has shown how RAS and the Hedgehog pathway interact in the development of pancreatic cancer in mice. Activation of cancer genes in the RAS family causes the tumor cells to secrete the factor (SHH) that activates Hedgehog signaling, and shuts off the tumor cell's own ability to respond to this type of stimulation.

The blocking of the Hedgehog response helps, in this phase, to secure the survival of the tumor cells while the surrounding cells are stimulated to grow. In a later phase, when the tumor has become more aggressive, the block is lifted so that tumor cell growth is also precipitated though Hedgehog signaling. The scientists have also identified the proteins that govern the tumor cells' sensitivity to SHH.

The Length of Cell Mutation

A significant breakthrough in the pancreatic cancer development mechanism has been achieved with the recent research performed at Johns Hopkins University School of Medicine and the Howard Hughes Medical Institute. The scientists found that pancreatic cancer may take up to 20 years to grow to the point where it is diagnosed by conventional medical doctors. This was determined by sequencing the DNA of cancer tumor cells from deceased patients. Because cancer mutations occur in growing tumors at a known rate, scientists were able to map the timing of the development of full-blown pancreatic cancer tumors.

Here
are the details of their findings:

• It takes 11.7 years for one mutation in a pancreas cell to grow into a "mature" pancreatic tumor (which might show up on a medical scan).

• It takes another 6.8 years for the pancreatic tumor to spread and cause tumors to appear in other organs of the body.

So, it takes about 20 years for a person to grow a cancer tumor and see it spread to the point where their doctor may diagnose them with pancreatic cancer. In other words, by the time doctors diagnose you with cancer, you've already been growing it for two decades.

This fact highlights the importance of changing your lifestyle in order to impede the possible cancer development, if you have a genetic predisposition, and the importance of the ongoing medical screening to catch the disease on early stages.

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