Lung Cancer and Polar/Circumpolar Alaskan Natives

• The most recent average incidence rate (age-adjusted to world standard population) of 315 per 100 000 (95% confidence interval, CI=248-382) represents a 33% surge (albeit non-significant) in Alaska Native cancer incidence over the initial period studied. 
• The male rate 366 (95% CI=266-466) for the same period exceeds the female rate 258 (95% CI=169-347) by 42%. 
• Two patterns of cancer incidence are seen at the village level. One, a 24 year upward trend found in the villages of Barrow, Point Hope and Kaktovik (combined rate of increase significant [P=0.047]) associated with lung cancer; and the other, a stable trend over the past 16 y, associated with colon and rectal cancer. 
• Lung cancer is the predominant cancer by site and is primarily a male disease. 
• The recent male lung cancer incidence rate of 137 (95% CI=73-201) exceeds the female rate by greater than five times. 
• Total lung cancer cases are primarily confined to four villages where the incidence significantly (P=0.0043) exceeds the remaining population. 
• The major female cancers are colon/rectal and breast with cancer of the cervix virtually eliminated. Breast cancer is found primarily in two villages where its excess is significant (P=0.025).
• Inupiat Eskimo cancer epidemiology is unique, differing from both the Alaska Native and other Circumpolar populations. 
• At present, this uniqueness cannot be explained by an overt environmental contaminant exposure. 
• Although tobacco very likely plays a central role, it by itself cannot fully explain the extremely high male lung cancer rate and why only specific villages are affected. 
• Genetic predisposition and environmental factors may play a synergistic role as cofactors. A cooperative investigative effort with the Inupiat population is indicated and may go a long way in reducing cancer concern in the region.

Causes of Lung Cancer

Researchers have discovered several factors that can cause lung cancer. The use of tobacco is the most important: About 90% of lung cancers are related to smoking. Harmful substances (carcinogens) in tobacco smoke damage the cells in the lungs. Over time, these damaged cells may develop into lung cancer.

The risk of developing lung cancer is related to how long a person has smoked and how many packs of cigarettes per day he or she smokes. A person who smokes one pack of cigarettes a day has 20 times the risk of developing lung cancer compared to a nonsmoker. Unfortunately, former smokers still are more likely to develop lung cancer than nonsmokers for many years after they quit smoking, and the risk never decreases to the low risk for a person who has never smoked. More than 50% of people newly diagnosed with lung cancer are former smokers who quit smoking more than a year before diagnosis.

A person living with a smoker has a 30% greater risk of developing lung cancer compared to a person living in a nonsmoking environment. Women appear to be more at risk from the chemicals in tobacco smoke that cause cancer. Therefore they may be at greater risk of developing lung cancer when they smoke or are regularly exposed to secondhand smoke.

Exposure to other harmful substances, such as, radioactive dust, and radon also increases the risk for lung cancer.

Symptoms

In the early stages of lung cancer, no symptoms may be present. As a result, only about 15% of lung cancers are diagnosed in the early stages when treatment is most effective.

Symptoms of more advanced lung cancer may include:

• A new cough or a cough that does not go away. Smokers who have a chronic cough from smoking may have a change in the frequency or severity of their cough.
• Chest, shoulder, or back pain that doesn't go away and often is made worse by deep breathing. About 5% of lung cancers spread to the chest wall, which can cause persistent chest pain.
• New wheezing.
• Shortness of breath.
• Hoarseness.
• Coughing up blood (hemoptysis) or bloody mucus.
• Swelling in the neck and face.
• Difficulty swallowing.
• Weight loss and loss of appetite.
• Increasing fatigue and weakness.
• Recurring respiratory infections, such as pneumonia.
• Clubbing of the fingers and toes. The nails appear to bulge out more than normal.

Tobacco

Studies show that tobacco use is the leading cause of lung cancer. 

• About 90% of lung cancers are caused by smoking. Smoking and chewing tobacco have been definitively linked to lung cancer, as well as to cancer of the mouth. About 1 in every 4 adults smokes cigarettes, significantly increasing the risk of lung cancer in these people. Even secondhand tobacco smoke is a risk factor for lung cancer.

The most important prevention measure is to not use any tobacco. If you do use tobacco, you can reduce your risk for lung cancer by quitting. Your risk will gradually decrease over 10 to 15 years as your lungs recover. Former smokers will still have a higher risk of developing lung cancer than nonsmokers even years after quitting smoking. The benefit of quitting smoking is greater if it occurs at a young age.

Source: Alaska Native Cancer Epidemiology in the Arctic  by R J Bowerman and Healthwise

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