Puff-free tobacco raises cancer risk
Chew, snuff take their toll in oral cancer diagnoses, WHO report says
Reuters
updated 4:05 p.m. PT, Tues., July. 1, 2008
LONDON - Chewing tobacco and snuff are less dangerous than cigarettes but the smokeless products still raise the risk of oral cancer by 80 percent, the World Health Organization's cancer agency said on Tuesday.
The review of 11 studies worldwide showed people who chewed tobacco and used snuff also had a 60 percent higher risk of esophagus and pancreatic cancer.
The researchers sought to quantify the risk of smokeless tobacco after a number of studies differed on just how dangerous the products were, said Paolo Boffetta, an epidemiologist at the WHO's International Agency for Research on Cancer.
"What we did was try to quantify the burden of smokeless cancer," he said in a telephone interview. "This has never been attempted in such a systematic way before."
The researchers, who published their findings in Lancet Oncology, did this by looking at population-wide studies and trials of both humans and animals.
They found frequency of use varies greatly both across and within countries, depending on sex, age, ethnic origin and economic background, and were highest in the United States, Sweden and India.
They also found that while snuff and chew were less dangerous than smoking because they were not linked to lung cancer, getting cigarette users to switch was not good public policy.
"If all smokers did this there would be a net benefit," Boffetta said. "The point is we don't know whether this would happen and there is no data to suggest these smokers would stop or switch."
Tobacco Effects
Cigarette smoking is the most popular method of using tobacco; however, there has also been a recent increase in the sale and consumption of smokeless tobacco products, such as snuff and chewing tobacco. These smokeless products also contain nicotine, as well as many toxic chemicals.
The cigarette is a very efficient and highly engineered drugdelivery system. By inhaling tobacco smoke, the average smoker takes in 1 to 2 mg of nicotine per cigarette. When tobacco is smoked, nicotine rapidly reaches peak levels in the bloodstream and enters the brain. A typical smoker will take 10 puffs on a cigarette over a period of 5 minutes that the cigarette is lit. Thus, a person who smokes about 1-1/2 packs (30 cigarettes) daily gets 300 “hits” of nicotine to the brain each day. In those who typically do not inhale the smoke—such as cigar and pipe smokers and smokeless tobacco users––nicotine is absorbed through the mucosal membranes and reaches peak blood levels and the brain more slowly.
Immediately after exposure to nicotine, there is a “kick” caused in part by the drug’s stimulation of the adrenal glands and resulting discharge of epinephrine (adrenaline). The rush of adrenaline stimulates the body and causes a sudden release of glucose, as well as an increase in blood pressure, respiration, and heart rate. Nicotine also suppresses insulin output from the pancreas, which means that smokers are always slightly hyperglycemic (i.e., they have elevated blood sugar levels). The calming effect of nicotine reported by many users is usually associated with a decline in withdrawal effects rather than direct effects of nicotine.
Medical Consequences of Tobacco Use
Cigarette smoking harms every organ in the body. It has been conclusively linked to leukemia, cataracts, and pneumonia, and accounts for about one-third of all cancer deaths. The overall rates of death from cancer are twice as high among smokers as nonsmokers, with heavy smokers having rates that are four times greater than those of nonsmokers. Foremost among the cancers caused by tobacco use is lung cancer—cigarette smoking has been linked to about 90 percent of all lung cancer cases, the number-one cancer killer of both men and women. Smoking is also associated with cancers of the mouth, pharynx, larynx, esophagus, stomach, pancreas, cervix, kidney, ureter, and bladder.
In addition to cancer, smoking causes lung diseases such as chronic bronchitis and emphysema, and it has been found to exacerbate asthma symptoms in adults and children. More than 90 percent of all deaths from chronic obstructive pulmonary diseases are attributable to cigarette smoking. It has also been well documented that smoking substantially increases the risk of heart disease, including stroke, heart attack, vascular disease, and aneurysm. It is estimated that smoking accounts for approximately 21 percent of deaths from coronary heart disease each year.
Exposure to high doses of nicotine, such as those found in some insecticide sprays, can be extremely toxic as well, causing vomiting, tremors, convulsions, and death. In fact, one drop of pure nicotine can kill a person. Nicotine poisoning has been reported from accidental ingestion of insecticides by adults and ingestion of tobacco products by children and pets. Death usually results in a few minutes from respiratory failure caused by paralysis.
Treatments for Tobacco Addiction
Nicotine Replacement Treatments
Nicotine replacement therapies (NRTs), such as nicotine gum and the transdermal nicotine patch, were the first pharmacological treatments approved by the Food and Drug Administration (FDA) for use in smoking cessation therapy. NRTs are used (in conjunction with behavioral support) to relieve withdrawal symptoms—they produce less severe physiological alterations than tobacco-based systems and generally provide users with lower overall nicotine levels than they receive with tobacco. An added benefit is that these forms of nicotine have little abuse potential since they do not produce the pleasurable effects of tobacco products—nor do they contain the carcinogens and gases associated with tobacco smoke. Behavioral treatments, even beyond what is recommended on packaging labels, have been shown to enhance the effectiveness of NRTs and improve long-term outcomes.The FDA’s approval of nicotine gum in 1984 marked the availability (by prescription) of the first NRT on the U.S. market. In 1996, the FDA approved Nicorette gum for over-the-counter (OTC) sales. Whereas nicotine gum provides some smokers with the desired control over dose and the ability to relieve cravings, others are unable to tolerate the taste and chewing demands. In 1991 and 1992, the FDA approved four transdermal nicotine patches, two of which became OTC products in 1996. In 1996 a nicotine nasal spray, and in 1998 a nicotine inhaler, also became available by prescription, thus meeting the needs of many additional tobacco users. All the NRT products—gum, patch, spray, and inhaler—appear to be equally effective.
Additional Medications
Although the major focus of pharmacological treatments for tobacco addiction has been nicotine replacement, other treatments are also being studied. For example, the antidepressant bupropion was approved by the FDA in 1997 to help people quit smoking, and is marketed as Zyban. Varenicline tartrate (Chantix) is a new medication that recently received FDA approval for smoking cessation. This medication, which acts at the sites in the brain affected by nicotine, may help people quit by easing withdrawal symptoms and blocking the effects of nicotine if people resume smoking.Several other nonnicotine medications are being investigated for the treatment of tobacco addiction, including other antidepressants and an antihypertensive medication, among others. Scientists are also investigating the potential of a vaccine that targets nicotine for use in relapse prevention. The nicotine vaccine is designed to stimulate the production of antibodies that would block access of nicotine to the brain and prevent nicotine’s reinforcing effects.
Behavioral Treatments
Behavioral interventions play an integral role in smoking cessation treatment, either in conjunction with medication or alone. They employ a variety of methods to assist smokers in quitting, ranging from self-help materials to individual cognitive-behavioral therapy. These interventions teach individuals to recognize high-risk smoking situations, develop alternative coping strategies, manage stress, improve problemsolving skills, as well as increase social support. Research has also shown that the more therapy is tailored to a person’s situation, the greater the chances are for success.
Traditionally, behavioral approaches were developed and delivered through formal settings, such as smoking-cessation clinics and community and public health settings. Over the past decade, however, researchers have been adapting these approaches for mail, telephone, and Internet formats, which can be more acceptable and accessible to smokers who are trying to quit. In 2004, the U.S. Department of Health and Human Services (HHS) established a national toll-free number, 800–QUIT–NOW (800–784–8669), to serve as a single access point for smokers seeking information and assistance in quitting. Callers to the number are routed to their state’s smoking cessation quitline or, in states that have not established quitlines, to one maintained by the National Cancer Institute. In addition, a new HHS Web site (www.smokefree.gov) offers online advice and downloadable information to make cessation easier.
Quitting smoking can be difficult. While people can be helped during the time an intervention is delivered, most intervention programs are short-term (1–3 months). Within 6 months, 75–80 percent of people who try to quit smoking relapse. Research has now shown that extending treatment beyond the typical duration of a smoking cessation program can produce quit rates as high as 50 percent at 1 year.
This information was obtained from: www.nida.nih.gov
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