The basic of Chemotherapy

Chemotherapy is a form of treatment usually for cancer. To understand how the Chemotherapy works, we need a little understanding of tumor cells. The tumor consists of a cell that reproduces an exceptionally high speed. Normal cells know to stop reproducing (or dividing) when in contact with other cells. When a tumor, this stop mechanism is missing, causing cells to continue dividing over and over again. RNA or DNA in a cell is like saying to reproduce, and chemotherapy works by destroying the RNA or DNA. The faster the cancer cells are replicating, chemotherapy is more able to kill cells.

Cell replication occurs in a series of steps, called the cell cycle. The cell cycle phases are: resting (G0, nothing happens), G1 (or gap 1, a phase of growth), S (synthesis, DNA replication occurs), G2 (gap 2, another growth) and M (mitosis, effectively from 1 division of cells in 2).

Some chemotherapeutic agents are able to kill a cell during each phase of the cycle (These are called cell-cycle non-specific), others are just dead for a certain phase and cannot operate in a dormant phase (the so-called cell-cycle specific). Give the cell cycle specific agents for different times, may reach the maximum number of cells that are particularly affecting.

These are more effective when given in divided doses (over several days or times, for example, once daily for 5 days or every three hours for 4 doses) or by continuous infusion. Cell-cycle nonspecific drugs act against cancer cells at any stage of the cell cycle, including the stage of rest. Cell-cycle nonspecific drugs are most effective when given in bolus doses (e.g., more than 20 minutes once).

This article writes by Joel W. Goldwein, MD & Carolyn Vachani, RN, MSN, AOCN
The Abramson Cancer Center of the University of Pennsylvania



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