Dry mouth drug may help prevent lung cancer in former smokers

  Article date: 2002/04/10,A drug that is used in Canada and Europe to treat dry mouth may be an effec

A drug that is used in Canada and Europe to treat dry mouth may be an effective agent for preventing lung cancer in former smokers, according to a report given at the April 9 at the 93rd Annual Meeting of the American Association for Lung Cancer Research.

The drug is not new — it was approved about 30 years ago in France. It is marketed in Canada as Sialor, and in Europe as Sulfarlem.
Drug Slowed Down Pre-cancerous Lesions

But when the drug, which is also known by the medical name anethole dithiolethione or ADT, was tested in an National Cancer Institute study of 101 current and former smokers it slowed the progression of pre-cancerous lesions by 22% compared to placebo (an inactive substance).

Former smokers responded better than current smokers, said the study’s lead investigator Stephen Lam, MD, chair of the Lung Tumor Section, BC Cancer Agency. Lam pointed out that even when smokers “follow our advice and quit smoking” they still have about a 15% increased risk of developing lung cancer.

“This drug may be our chance to really do something to help them,” Lam said.

Frank Rauscher III, PhD, deputy director of the Wistar Institute, Philadelphia, said the drug triggers production of glutathione S-transferase (GST), which is the body’s natural defense mechanism against carcinogens.

“This enzyme breaks down the carcinogens found in both tobacco and in the environment,” Rauscher said.

“We have been searching for a compound that is not toxic, doesn’t cause mutations, and yet can break down and destroy the carcinogens,” said Rauscher. He said the findings are so significant that “a large trial should go forward immediately.”

In the study, 101 current and former smokers who had precancerous lesions called bronchial dysplasia took either 25 mg of the study drug three times a day or placebo for six months. Before starting the study all volunteers had screening and biopsy with bronchoscopy. The bronchoscopy and biopsy procedure was repeated at the conclusion of the study.

In ADT-treated patients the rate of progression of new lesions was 8%, compared to 17% progression in patients treated with placebo, said Lam. In the person-specific analysis, the progression rate was 22% lower, he said.
Drug Needs Scrutiny in Large US Studies

The drug is not approved in the US, but that may change. Solvay Pharma, maker of the drug, is in discussions with both the National Cancer Institute, which funded this study, and the FDA.

According to Herman Kattlove, MD, medical editor at the ACS, before this drug is marketed it needs to be shown to actually prevent cancer and save lives.

“After all,” said Kattlove, “the drug only slowed the rate of progression for six months. That may just mean that the cancers will take a little longer to develop. And, smokers need to remember that this is only for people who stopped smoking."

According to the American Cancer Society about 169,400 new cases of lung cancer are expected in 2002, this is 13% of cancer diagnoses for 2002. The ACS estimates there will be 154,900 lung cancer deaths in 2002, which is 28% of all cancer deaths expected in 2002.

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