Another major reason for the fact that most cancer growths finish up being more seriously damaged by radiation than most normal tissues is that normal tissues are better at repairing injuries. However normal tissues are injured — whether by cutting, burning, infection, radiation or anything else — they get to work and repair the damage. Repair processes are stimulated by chemicals produced at the site of injury. Cancer cells, having escaped the body’s normal controls over division of cells, are not stimulated to divide by these chemicals. Thus, during breaks between radiation treatments, normal tissues are busy repairing the damage while tumours are not. Repair of normal tissues is carried out partly by division of the cells within the damaged area. In addition, some types of normal cells migrate into the damaged area from other parts of the body. There is no equivalent form of help available for tumours.

While it is true that normal tissues are generally able to repair radiation damage better than tumours, there is a limit to their ability to do this. You know this from experience with other types of injuries. Let us take a simple example. A skin scratch can heal without leaving any mark. A small cut may heal without any help, leaving a small scar. A larger cut may only heal with the help of stitches. If a big chunk of skin and underlying tissues is actually removed, the defect may never heal over without grafting. The eventual appearance and function of an injured tissue depends on how severe the injury was.

*258/40/1*

Related Posts:

• COMPLICATIONS FOLLOWING BREAST CANCER OPERATIONS