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Cancer patients who continue to smoke beware
HOUSTON---Smokers successfully treated for head and neck squamous cell cancer have greater chances of getting another cancer or having the cancer recur if they do not quit smoking, according to study at The University of Texas M. D. Anderson Cancer Center.
The findings came from an interim analysis of a study examining the benefits of chemotherapy for preventing the recurrence of cancer or for preventing a secondary primary cancer from occurring.
M. D. Anderson's Dr. Fadlo Khuri, co-principal investigator, and Dr. Waun Ki Hong, principal investigator, presented the results at the American Society of Clinical Oncology's annual meeting in Atlanta.
"This is the first large-scale prospective study evaluating smoking status and its impact on recurrence rates and the rate of a second primary tumor (SPT) developing in patients diagnosed with head and neck squamous cell cancer," said Dr. Khuri. "The results indicate significantly higher cancer recurrence rates in active versus former smokers, and higher smoking related SPT rates in active versus never smokers."
The study was launched in 1991 to evaluate the efficacy of low dose 13-cis-retinoic acid, a synthetic analog of Vitamin A, for preventing a second primary tumor in patients treated for Stage I or Stage II squamous cell carcinoma of the larynx, oral cavity or pharynx. All of the patients in the Phase III placebo-controlled, double-blind study were previously treated successfully with surgery and/or radiation therapy, and each began the study within 36 months of his or her initial cancer diagnosis.
A total of 1,125 study participants -- including 132 patients who have never smoked and 401 patients who continued to smoke after treatment -- are included in the medical study. Each agreed to take a daily dose of 13-cis-retinoic acid, or a placebo, for three years, and then to be available for four years after the initial three-year period. Study participants, on average, have been in the medical study for two years and eight months, Dr. Khuri said, with actual participation ranging anywhere from just a few days to more than seven years.
To date, of the 1,125 study participants enrolled, 140 have developed a second primary tumor and 98 have had relapses of their head and neck cancer. Two patients experienced both a relapse and a second primary tumor, Dr. Khuri said. He noted that among the 147 participants who never smoked, 12 experienced a second cancer, and only six were smoking-related cancers -- cancers of the head and neck, lung, esophagus or bladder. Of the 401 patients who continued to smoke, 63 were later diagnosed with a second primary tumor, and of these 63 cases, a total of 43 were smoking-related cancers.
The researchers also found that patients with larger primary tumors had a higher rate of recurrence and second primary tumors. In addition, they found that more smoking-related second primary tumors occurred in patients with Stage II cancer (4.7 percent per year) than with Stage I cancer (2.5 percent per year).
"Our study points to an important message to smokers, and that is they should quit if they've been treated for head and neck squamous cell cancer," Dr. Khuri said. "If you're treated successfully for head and neck squamous cell cancer, you have a good chance of being treated effectively. It's the second cancer, or the second primary tumor, that is usually fatal," he stressed.
Dr. Khuri pointed out that the study has not been "unblinded," so that neither the researchers nor the patients know who is taking the drug and who is taking the placebo.
"These findings are preliminary results from a larger study involving the benefits of chemoprevention," Dr. Khuri explained.
The brand name of the drug involved is Accutane, a pharmaceutical originally developed for treating acne. It is produced by the Hoffman LaRoche drug company.
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5/18/99
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