• E-mail
• Print
• Comment
• Font Size
• Digg
• del.icio.us
• Discuss article

Transplants' Cancer Threat; Experts Say Patients Should Receive Drugs That Reduce Their Risks

Posted on: Tuesday, 6 December 2005, 06:00 CST

By A.J. Hostetler

Transplant patients at risk for cancer should be treated with drugs that may decrease that risk as well as prevent organ rejection, researchers say in a new study.

Following a transplant, recipients take powerful drugs to suppress their immune systems and prevent organ rejection. Transplantation took off in the 1980s with the development of cyclosporine, an immunosuppressive drug that drastically improved patients' chances of recovery.

"It allowed for transplantation of organs other than kidneys," said Dr. Anne King, the medical director of Virginia Commonwealth University's kidney and pancreas transplant program.

But in recent years doctors, including King, have noticed that patients on cyclosporine and related drugs seemed more likely to develop some cancers.

"The immune system surveys the body for cells that are damaged or abnormal cells," King said. "It also acts to prevent cancer growth." But drugs that allow transplants "also tip the scales in favor of malignance potential."

Transplant recipients have a higher risk of developing cancer following their surgery, particularly skin cancer. The risks of cervical, breast and colorectal cancer are also increased.

A 1993 study concluded that cancer kills a quarter of kidney recipients, the largest group of transplant patients. In a 2000 study, cancer also killed about a quarter of liver recipients who survived a year, and in a 1997 study, a fifth of heart transplants after two years.

Now, a team led by researchers from the Richmond-based United Network for Organ Sharing (UNOS) suggests not only that cyclosporine and related drugs raise the risk of solid-organ tumors but that newer drugs may lower that risk.

The study, published in the journal Transplantation, examined the patient history of 33,249 kidney recipients from 1996 to 2001. The analysis examined the incidence of cancer among patients who took cyclosporine, tacrolimus or similar drugs versus those treated with newer drugs called mTOR inhibitors, such as Rapamune or Rapamycin. Those who took a combination of drugs were also studied.

Only three of 504 patients taking the inhibitors alone developed malignancies, all of them skin cancers.

However, there were 552 cancers among patients taking cyclosporine or tacrolimus alone, including 252 skin cancers and 300 solid tumors, such as prostate, lung, breast and colorectal. Among the 2,321 taking a combination, there were three skin cancers and 11 solid tumors.

The mTOR inhibitors reduced the relative risk of new cancers by 59 percent.

"Our study clearly shows that the mTOR inhibitors offer a significant benefit in reducing short-term malignancy rates in transplant recipients," said Dr. H. Myron Kauffman, a senior research scientist at UNOS.

The problem appears to stem from the ability of cyclosporine- like drugs to promote certain growth factors associated with cancer in animals. In other animal studies, however, the mTOR drugs were shown to inhibit specific growth factors.

UNOS manages the national Organ Procurement and Transplantation Network.

Source: Richmond Times - Dispatch

More News in this Category