Gene Therapy Can Improve Some Cancer Treatments

It's not a cure for cancer, but there is new evidence that a type of gene therapy really helps to shrink tumors and prolong life in seriously ill patients--people that were thought to be untreatable.

The study, in today's issue of the journal Nature Medicine, looked at gene therapy combined with traditional chemotherapy for people with advanced cancer of the head and neck. The treatment shrank tumors in almost 85% of patients, and completely got rid of the tumors in some of these patients.

CBSHealthWatch medical correspondent Dr. Emily Senay reports that even in cases where the tumor only shrank a little bit, it was enough to make it possible to perform surgery to remove the rest where previously it was inoperable.

The gene therapy also helped to keep the tumors away. While tumors that affect the head and neck often come back after treatment, when treated with gene therapy only 17 percent recurred. This latest study is important, Senay says, because it shows that gene therapy and chemotherapy used together are more effective than either used alone, and this kind of combination therapy is likely to become a common prescription for cancer patients.

Experts believe that as many as 75% of all cancers occur partly because a gene known as p-53 becomes damaged. In a healthy person, the p-53 gene causes potentially cancerous cells to self-destruct. But when p-53 itself is damaged, cell growth is left unchecked, cells become cancerous and a tumor grows.

Gene therapy in these cases involves injecting a normal copy of the p-53 gene into the tumor, replacing the defective gene and causing the cancerous cells to self-destruct.

Senay says that since this research is only a phase II clinical trial, there is still some more work to be done. It is most likely that for some types of cancer it could be approved and on the market in two to three years.

Gene therapy is safe, Senay says, even after the death early this year of a young man who was being treated for a rare liver disorder in early trials. There are many very different kinds of gene therapy, she adds.

With any new therapy there is always a certain amount of risk given that it's a totally new and untested approach, Senay says, but the clinical trial process is designed to test safety first, and this cancer therapy has been used on hundreds of patients with good results.

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