The Number One Cause of Lung Cancer is Smoking

Smoking causes approximately 5 million deaths worldwide each year. According to Assoc. Prof. Dr. Tayfun Çalışkan, a Specialist in Pulmonary Diseases at Anadolu Medical Center, smoking contains more than 7,000 chemical substances that cause DNA damage and have harmful effects on cellular functions. He stated, “The most common known cause of lung cancer is smoking. About 80-90% of all lung cancers are related to smoking and can be prevented by quitting smoking. According to cancer statistics for 2022, lung cancer is the most common cancer in the United States after prostate and breast cancer. For smokers, the risk of developing lung cancer by the age of 80 is 14%.” Assoc. Prof. Dr. Tayfun Çalışkan provided important information regarding the harms of smoking.

How Common is Tobacco Consumption?

Cigarettes contain more than 7,000 chemical substances (over 60 of which are known carcinogens) and have harmful effects on cellular functions by causing DNA damage. The annual global economic burden of smoking is $2 billion, and it results in the deaths of half of the users. Smoking causes approximately 5 million deaths each year. It is estimated that among the global population aged 15 and older, there are 942 million male smokers and 175 million female smokers. Smoking rates vary by gender across countries. According to the International Tobacco Use Survey, in 2016, the rate of smoking in Turkey was found to be 31.6% of the total population, 44.1% in men, and 19.2% in women.

What Diseases Does Smoking Cause in the Lungs?

The most well-known disease associated with smoking is lung cancer. Additionally, smoking during pregnancy and exposure to cigarette smoke during early childhood disrupts lung development in children and increases the risk of developing asthma. In asthmatic patients who smoke, the risk of developing chronic obstructive pulmonary disease (COPD) is higher than in non-smokers. COPD is the most commonly seen lung disease related to smoking; it manifests with chronic cough, sputum production, and shortness of breath, and it is a chronic, progressive, and preventable disease. The most effective method to reduce the progression of COPD and associated deaths is quitting smoking. Furthermore, smoking can lead to a series of diseases known as interstitial lung disease (lung scarring), which disrupt the normal functioning of the lungs by damaging their spongy structure. Among these, respiratory bronchiolitis, desquamative interstitial pneumonia, and Langerhans cell histiocytosis have a strong association with smoking. Other diseases more commonly seen in smokers include idiopathic pulmonary fibrosis and rheumatoid arthritis-related interstitial lung disease.

What is the Frequency of Lung Cancer Associated with Smoking?

The most commonly known cause of lung cancer is smoking. About 80-90% of all lung cancers are related to smoking and can be prevented by quitting. In patients who smoke, the risk of developing cancer is 30 times higher compared to non-smokers. According to cancer statistics for 2022, lung cancer was the most frequently diagnosed cancer in the United States (USA), with 236,740 new cases, following prostate and breast cancer. Additionally, lung cancer accounted for the most deaths among cancers, with 130,180 cases. The risk of developing lung cancer for smokers is found to be 14% by the age of 80.

Are All Lung Cancers Associated with Smoking?

Worldwide, it has been determined that 15-20% of men with lung cancer and 50% of women with lung cancer are not associated with smoking. When evaluating risk factors other than smoking, advanced age, air pollution, environmental exposures (such as asbestos, chromium, arsenic), biomass exposure (wood and coal burning, cooking, smoke exposure), the use of dried animal dung as fuel, radon exposure, genetic factors (family history of lung cancer), chemotherapy-radiotherapy history, and the possible roles of viruses (such as Epstein-Barr virus, human papillomavirus, hepatitis B, and C) are known to contribute to lung cancer.

Can Lung Cancer Occur in Non-Smokers? What is Its Frequency?

In the USA, approximately 10-20% of lung cancers occur in non-smoking patients, and it is expected that between 20,000 and 40,000 new cases of lung cancer will develop annually in non-smokers.

What is the relationship between smoking duration and intensity with cancer?

The duration and intensity of smoking affect the risk of lung cancer. Individuals who smoke 1-5 cigarettes a day have a 9-fold higher risk of developing lung cancer compared to non-smokers. Among those who smoke 1-5 cigarettes daily and quit smoking before the age of 40, the risk of developing lung cancer is similar to that of non-smokers. However, individuals who smoke 6-15 cigarettes a day have an 1.8-fold higher risk of developing lung cancer compared to non-smokers, even if they quit smoking before the age of 40. For those who smoke 1-5 cigarettes daily and quit after the age of 40, the risk of lung cancer is found to be 3 times higher than that of non-smokers. Those who start smoking at an older age have a higher risk of lung cancer compared to those who start at a younger age. The risk of lung cancer is 7.7% among those who smoke 1-5 cigarettes a day, while it is 26.4% among those who smoke more than 35 cigarettes a day.

What is passive smoking? What are its risks?

Passive smoking refers to secondary exposure, where a person is directly exposed to the smoke of someone else's cigarette. Tertiary exposure occurs when smoking in closed environments leads to the accumulation of chemicals such as nicotine, formaldehyde, and naphthalene on soft surfaces like clothing, furniture, bedding, and curtains, and subsequent exposure to these surfaces. In the United States, more than 7,300 annual lung cancer cases in non-smokers are attributed to secondary smoke exposure. Additionally, it can lead to coronary artery disease, stroke, and low birth weight in pregnant women. Furthermore, in infants and children, it can cause sudden infant death syndrome, lung infections, ear infections, and asthma attacks.

What is the relationship between the use of hookah and cigars with cancer?

Charcoal is used to heat hookah tobacco. This charcoal contains high levels of carbon monoxide, metals, and chemicals that can cause cancer. These toxic agents can reach the lungs in high concentrations even if they are inhaled through water. They can cause lung, bladder, stomach, and oral cancers. Users often believe that hookah is less harmful than cigarettes, but studies have shown that nicotine, tar, and other heavy metals found in cigarettes are also present in hookah smoke. One hour of hookah use is equivalent to smoking 100-200 cigarettes. During this hour, individuals inhale 9 times more carbon monoxide and 1.7 times more nicotine compared to smoking one cigarette. Similarly, individuals who smoke cigars also develop lung, esophageal, oral cavity, throat, and pancreatic cancers. The belief that not inhaling cigar smoke makes it less harmful is a misconception. Cigars cause less lung cancer than cigarettes but more than non-smokers. Regardless of whether the smoke is inhaled, similar to cigarettes, it directly interacts with the lips, mouth, tongue, throat, and esophagus, and accumulates in saliva, which can then be swallowed and reach the esophagus, leading to similar cancers in these regions.

Does electronic smoking cause cancer? What are its harms?

Electronic cigarettes contain potentially toxic substances. Propylene glycol and vegetable glycerin are toxic to cells. Additionally, the substances such as acetaldehyde, acrolein, and formaldehyde in electronic cigarettes can lead to lung and heart diseases. Acrolein, a herbicide used to kill harmful plants, can cause acute lung injury, chronic obstructive pulmonary disease (COPD), asthma, and lung cancer through inhalation.

Is the use of electronic cigarettes suitable for quitting smoking?

The use of electronic cigarettes for the purpose of quitting smoking has also been studied, and no effectiveness in smoking cessation has been found (U.S. Food and Drug Administration). Animal studies have shown that they can cause lung and bladder cancer.

What is a smoking cessation clinic? What tests and treatments are offered to patients who want to quit smoking?

In a smoking cessation clinic, individuals who use tobacco products and wish to quit are provided with psychosocial support, and necessary medical treatments, including pharmacotherapy and nicotine replacement therapies, are applied to assist in quitting smoking. These clinics have been operating in Turkey since 2011. The generally desired tests include chest X-rays, pulmonary function tests, blood tests, electrocardiograms (ECGs), as well as measuring carbon monoxide levels in exhaled air, and administering the Fagerström dependence questionnaire. In necessary cases, consultations with cardiology and psychiatry may also be requested. Nicotine replacement therapies can include nicotine patches, gum, nasal sprays, sublingual tablets, lozenges, and inhalers. Medications used for smoking cessation include bupropion and varenicline. However, varenicline was recalled by the manufacturer 1.5 years ago due to the presence of suspected carcinogenic substances (nitrosamines) and is not currently in use.

What are the smoking cessation rates in smoking cessation clinics?

In the United States, 90% of patients who successfully quit smoking did so through self-quit methods, stopping abruptly. In this method, individuals utilized smoking cessation guides and over-the-counter medications. Success in quitting smoking is defined as not smoking for one year. In self-quit strategies, the success rate is reported to be between 8-25%, while the success rate among individuals who attend smoking cessation clinics is found to be between 20-40%.

Are alternative treatments such as acupuncture and bioresonance recommended for smoking cessation?

Some studies have been conducted on alternative treatment methods such as acupuncture and bioresonance for smoking cessation, which have been reported to be beneficial compared to placebo. However, currently, these types of practices are not included in national and international guidelines related to smoking cessation.