Chemotherapy May Paradoxically Trigger Future Cancer

Research has revealed that some drugs used in chemotherapy may actually cause conditions that can lead to the future growth of a cancerous tumor.

Chemotherapy drugs work by interfering with the ability of cancer cells to divide and reproduce themselves. The affected cells become damaged and eventually die. As the drugs are carried in the blood, they can reach cancer cells all over the body. Chemotherapy has to be carefully planned so that it progressively destroys the cancer during the course of treatment but not the normal cells and tissues.

Prof. Batsheva Kerem of the Hebrew University of Jerusalem (Jerusalem, Israel) and colleagues have been studying the chromosomes in cancer cells. They found that cancer cell chromosomes break recurrently at specific regions known as "fragile sites,” sites where the mechanism responsible for DNA replication is disturbed. This could lead to breakage resulting in multiple rearrangements of the chromosomes, a striking characteristic of cancer cells.

Now the researchers report that normal cells also develop fragile regions when they are exposed to certain conditions. Some of the drugs used in chemotherapy may cause these conditions and thus plant the seeds of a future cancerous growth at the same time they are killing the current one. There are some 100 fragile sites in the human genome and five of these sites are now being studied. These findings were reported in the inaugural edition of Cancer Cell, published February 26, 2002.

The researchers say this work creates a better understanding of how chemotherapy drugs work, which will help guide the development of a new generation of drugs designed to halt the growth of cancer cells without inducing fragile sites in normal cells.




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