Hair loss from chemotherapy, a distressing side effect of cancer treatment, could be a thing of the past if a gel under development shows promise in adults.

Cancer cells grow faster than normal tissue. Chemotherapy works by killing cells that are rapidly dividing. An unintended side effect is damage to the hair follicles, where cells also divide more quickly than cells in other organs of the body.

The Glaxo drug works by temporarily stopping the follicles from dividing, a sort of suspended animation, shielding them from the effects of chemotherapy. The effect wears off within a day and does not seem to make any difference in long-term hair growth. The compound, code-named GW8510, inhibits an enzyme called cyclin-dependent kinase 2, one of the basic stimulants of cell division.

In the experiments, scientists gave rats a chemotherapy drug called etoposide. Without treatment, 90 percent of the rats had hair loss. GW8510 prevented this totally in half of the rats. In the rest, its effectiveness ranged from 25 percent to 75 percent. The gel also appears to protect hair from some other common cancer drugs, such as Adriamycin and cyclophosphamide.

So far the clear ointment has only been tested only on lab rats, but developers said its effects are dramatic. "We noticed a marked protection of the hair," said Stephen T. Davis. He said it is not absorbed into the blood stream. As far as can be told from rat experiments, it is safe and carries no side effects.

Davis said that if further testing holds up, patients would rub the gel into their hair before getting their cancer treatment and then wash it out a few hours afterward. Davis, a scientist at Glaxo Wellcome, said the company hopes to test the ointment on people, though he could not predict when that will happen.

Dr. William N. Hait, director of the Cancer Institute of New Jersey, complimented the research. "This is part of an effort of cancer researchers around the world to make treatment a lot more tolerable."' Hait said that a treatment for hair loss is much needed. Some patients avoid getting screened for cancer because they fear hair loss and other side effects of chemotherapy.

The drug needs more research before it can be confidently put forward as an effective method of blocking hair loss due to chemotherapy. In some clinics attempts are made to stop hair loss by applying ice packs to the scalp during chemotherapy. This slows down hair follicle activity and makes the hair follicles more resistant to the effects of chemotherapy drugs. However, concern has been raised over this approach as the technique can temporarily slow down cancer cells and make these more resistant to the chemotherapy too. Some cancer cells, if they are present in the skin, may avoid destruction by the chemotherapeutic drugs.

With the new Glaxo-Wellcome drug similar concerns also come to mind. It may be possible for the drug to "hide" cancer cells in the skin and reduce the effectiveness of chemotherapy. Further research will define whether this is a problem or not. Ideally, drugs to prevent hair loss during chemotherapy would be specifically targeted to hair follicle cells and would have no affect on other skin cells. This would enable the drug to be used in chemotherapy treatment of almost all cancers except perhaps basal cell carcinomas which sometimes develop from hair follicle cells.