Smoking and Not Only Lung Cancer

14.8% of HK’s population >15 years old are smokers (2006) compared with 23.3% in 1982 and 12.4% in 2000. 85% are males, 24.5 % of males and 4% of females. There was a doubling of form 3 female smokers between 1994 and 1999 (6-12%).

Smoking and Premature Death
Smoking is the single largest cause of premature and preventable death in developed countries. In developing countries, smoking ranks third after infectious diseases and malnutrition. In 1999, 3.2 million deaths were from smoking related diseases. By 2020, there will be 10 million deaths/year (70% in developing countries). 20% of deaths are attributable to smoking. 50% of long-term users will die of a tobacco related disease. Long-term smokers lose 10 years on average (10 minutes per cigarette). There are more than 4,000 chemicals including poisons, toxins and other irritants in cigarette smoke. A smoker’s risk of heart attack is more than twice that of nonsmokers.

Smoking Causes Sudden Cardiac Death
Cigarette smoking is the biggest risk factor for sudden cardiac death. Whereas hyperlipidemia contributes to 20% excess risk of coronary artery disease and diabetes mellitus and hypertension each contribute 50% excess risk, smoking accounts for 200%. Cigarette smoking doubles the risk of a stroke. Smoking damages the cardiovascular system. Cigarette smoke makes clotting more likely. Smoking cessation today would significantly cut risk of stroke within two years.

Smoking and Pregnancy
For women planning a pregnancy smoking causes reduced fertility, early menopause, increased likelihood of delayed pregnancy, complications of pregnancy, reduced oxygen to placenta and significantly increased risk of sudden infant death syndrome (SIDS). Smoking during pregnancy causes 20 - 30% of low birth-weight babies, up to 14% of preterm deliveries, 10% of all infant deaths and 4 times the incidence of negative behavior in toddlers

Passive Smoking and Children
Passive smoking increases the following in children: asthma, pneumonia, bronchitis, fluid in the middle ear. Third hand smoke exposure in children (smoke absorbed onto clothes, upholstery etc.) impairs brain development and increases the risk of later malignancy.

Why do People Smoke
A HK study showed that people smoke because of:

Influence of friends – 51%
Out of curiosity – 16%
Refreshing one’s mind – 7.2%
Influence of family members – 7.1%
Necessary at social functions – 5.6%
Look mature / stylish – 3.2%
Deal with stress – 3.1%

Smoking and Cancer
Tobacco causes 80-90% of all cancers. There is a clear dose-response relationship between the number of cigarettes smoked per day and the incidence of lung cancer. Cigarette smoking causes damage to the DNA in the cells of the bronchial epithelium. The risk of lung cancer increases in cigar and pipe smokers, depending on inhalation practices. Smokeless tobacco (chewing tobacco and snuff) are carcinogenic for the upper aero digestive tract but not for the lungs. It is estimated that 25% of lung cancer in non smokers comes from passive exposure to cigarette smoke. Passive smoke differs significantly from mainstream smoke inhaled by the active smoker and may be even more carcinogenic. Several studies show that spouses of smokers have a two to three fold increased risk of developing lung cancer. Other carcinogens include asbestos, radon, polycyclic hydrocarbons, cadmium, ethers, nickel, chromium and inorganic arsenic. It has been conjectured that air pollution may promote the action of other carcinogens but is not carcinogenic alone.


Symptoms of Lung Cancer
Symptoms of lung cancer may be local or generalised; local symptoms include cough, shortness of breath, chest pain and coughing up blood. 75% of patients are inoperable at presentation. Lung cancer often presents with non specific symptoms such as tiredness or symptoms of advanced or metastatic disease that can involve the bones, brain and pericardium.

Lung Cancer and Physical Activity
Data drawn from the ß-Carotene and Retinol Efficacy Trial, a lung cancer chemoprevention trial suggest that cancer incidence may be more attenuated by physical activity for men and mortality more attenuated for women. Effects may be more pronounced for younger people and may differ inconsistently by pack-years of smoking. The authors concluded that physical activity may play a role in reducing cancer risk and mortality among those with significant tobacco exposure.


Key Messages:
Smoking is the single largest cause of premature and preventable death in developed countries.
Cigarette smoking is the biggest risk factor for sudden cardiac death
Third hand smoke exposure in children impairs brain development and increases the risk of later malignancy.

Article Written by Dr Edwin Poon
Image credit: http://www.andrew.cmu.edu