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Smoking and cancer

Many cancer patients continue smoking during or after a cancer treatment. Since the middle of the last century, numerous scientific studies showing a direct link between smoking and the risk posed to individuals’ health have been published. And today smoking remains a big public health issue, not only because it is the number one cause of lung cancer, but also because it is the main preventable cause of all cancers, not to mention other diseases such as cardiovascular maladies and lung illnesses.

Tobacco use during treatment

A 30-year follow-up demonstrated that there is evidence that tobacco smoking aggravates and prolongs radiotherapy-induced complications. Of particular importance is evidence that continued smoking is associated with adverse effects during anti-cancer treatment. Smoking can promote tumor progression and increases resistance to chemotherapy due to nicotine-induced resistance to apoptosis by modulating mitochondrial signaling [1]. The same study also reported that non-smokers report less severe pain compared to smokers.

Tobacco may reduce the effectiveness of cancer treatments and increase the risk of complications for all types of cancer treatment [2, 3]. Complications can arise in the three main areas of cancer treatment, as reported and validated by

Surgery: smoking can increase the risk for infection and cause slower healing of surgical wounds. There is a higher risk of problems during anesthesia for smokers compared to non-smokers, also related to the higher risk for lung and heart complications.
Radiation Therapy: effectiveness of radiation treatment is lower for smokers. Smoking during treatment increases the risk of side effects, such as inflammation of the mouth and throat, loss of taste, dry mouth, fatigue, weight loss, inflammation of the lung tissue, bone and soft tissue damage and damage on the vocal quality.
Chemotherapy: in general, it can be told that smoking during chemotherapy can increase side effects, such as weight loss with muscle weakness, fatigue, lung and heart problems. One possible reason is that tobacco could alter the metabolism of certain chemotherapies and targeted therapies [4].
Avoidance beliefs about the effect of smoking on cancer will also impact early-diagnosis. Research showed that smokers hold more pessimistic and avoidant beliefs about cancer, which could deter early-detection behavior [2].

Secondhand smoke

Secondhand smoke has been proven to have a carcinogenic effect (causing cancer). Secondhand smoke is also called environmental tobacco smoke, involuntary smoke, and passive smoke, and is defined by the National Cancer Institute as the combination of “sidestream” smoke (the smoke given off by a burning tobacco product) and “mainstream” smoke (the smoke exhaled by a smoker). The amount of smoke created by a tobacco product depends on the amount of tobacco available for burning. The amount of secondhand smoke emitted by smoking one large cigar is similar to that emitted by smoking an entire pack of cigarettes [5]. Studies indicated that a non-smoker who lives with a smoker can increase the risk of getting lung cancer by 20% to 30%. There are also immediate effects related to inhalation of secondary smoke, being irritations on the airways and harmful effects on a persons’ heart and blood vessels.

Legislation prohibiting smoking in public places has shown to impact smoking restrictions in family cars and homes of families with children between 10 and 11 years old. A survey in Wales (UK) pointed out that, after introducing smoking bans in public places, the number of families allowing smoking in cars dropped from 18% prior to legislation to 9%. The percentage where smoking was allowed in homes dropped from 37% to 26%. Both figures show that creating public awareness about the impact of smoking in public places also has its consequences in the family habitat [6]. Try to avoid places with increased risks for secondhand smoking.

Benefits of quitting smoking

Several studies have indicated a better prognosis for people who quit smoking after diagnosis compared to non-quitters. One particular study on lung cancer estimated a 33% five year survival in 65 year old patients with early stage non-small cell lung cancer who continued to smoke compared with 70% in those who quit smoking. This demonstrates the quitting smoking can be beneficial for the studies population [7]. Other studies have indicated an increase quality of life of people who stop smoking and a decreased risk for developing secondary tumors.

The American Cancer Society has made a list of the benefits of quitting smoking over time [8]:

  • 20 minutes after quitting: Your heart rate and blood pressure drop [9].
    12 hours after quitting: The carbon monoxide level in your blood drops to normal [10].
  • 2 weeks to 3 months after quitting: Your circulation improves and your lung function increases [11].
  • 1 to 9 months after quitting: Coughing and shortness of breath decrease; cilia (tiny hair-like structures that move mucus out of the lungs) start to regain normal function in the lungs, increasing the ability to handle mucus, clean the lungs, and reduce the risk of infection [12].
  • 1 year after quitting: The excess risk of coronary heart disease is half that of a continuing smoker’s [13].
  • 5 years after quitting: Risk of cancer of the mouth, throat, esophagus, and bladder are cut in half. Cervical cancer risk falls to that of a non-smoker. Stroke risk can fall to that of a non-smoker after 2-5 years [14].
  • 10 years after quitting: The risk of dying from lung cancer is about half that of a person who is still smoking. The risk of cancer of the larynx (voice box) and pancreas decreases [15].
  • 15 years after quitting: The risk of coronary heart disease is that of a non-smoker’s [16].

Being aware of the triggers that make you smoke

Several factors that influence smoking initiation and pursuance are peer pressure, cultural smoking, genetic factors or environmental influences. Studies have shown that surrounding influence, stress, fun and peer pressure were the major reasons for smoking initiation [17]. As a cancer patient who smokes, it is important to recognize the triggers to grasp for a cigarette and to avoid situations that activate these triggers.

Demographics of smoking

According to the World Health Organization, there are about 1.1 billion smokers in the world. Half of them will die prematurely as a result of their smoking behavior. Smoking is one of the world’s most important cause of preventable death, killing globally about five million people due to active or secondhand smoking [18]. The Office of National Statistics (UK) reported in their ‘Report on Smoking in England’ that 20% of adults, aged 16 and over, were smokers in 2012. In 2002 this figure has been reported to be 26%. Unemployed people were reported to smoke more (39%) compared to those in employment (21%) or economically inactive (17%) [19]. According to the same report, about 17% of all deaths in the UK in 2013 were caused by smoking. The figure for the U.S.A. are similar, with about 18% of the population that smokes. About 20,5% of adult men have been reported to smoke compared to 15,3% of adult women. For the age group of 65 years and older 9% are smokers [20].


  • [1]. Florou et al (2014), Clinical Significance of Smoking Cessation in Subjects With Cancer: A 30-Year Review
  • [2]. Quaife et al (2015); Smoking is associated with pessimistic and avoidant beliefs about cancer: results from the International Cancer Benchmarking Partnership.; Br J Cancer. 2015 May 26;112(11)
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  • [4]. Rivera et al. (2015); Consequences of tobacco smoking on lung cancer treatments. Rev Pneumol Clin. 2015 Feb 26
  • [5]. Second hand smoke fact sheet.
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  • [7]. Parsons et al (2010), Influence of smoking cessation after diagnosis of early stage lung cancer on prognosis: systematic review of observational studies with meta-analysis;BMJ. 2010 Jan 21;340:b556
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  • [9]. Effect of smoking on arterial stiffness and pulse pressure amplification, Mahmud A, Feely J.Hypertension.2003:41:183
  • [10]. US Surgeon General’s Report, 1988, p. 202
  • [11]. US Surgeon General’s Report, 1990, pp.193, 194,196, 285, 323
  • [12]. US Surgeon General’s Report, 1990, pp. 285-287, 304
  • [13]. US Surgeon General’s Report, 2010, p. 359
  • [14]. A Report of the Surgeon General: How Tobacco Smoke Causes Disease – The Biology and Behavioral Basis for Smoking-Attributable Disease Fact Sheet, 2010; andTobacco Control: Reversal of Risk After Quitting Smoking.IARC Handbooks of Cancer Prevention, Vol. 11. 2007, p 341
  • [15]. A Report of the Surgeon General: How Tobacco Smoke Causes Disease – The Biology and Behavioral Basis for Smoking-Attributable Disease Fact Sheet, 2010;and US Surgeon General’s Report, 1990, pp. vi, 155, 165
  • [16]. Tobacco Control: Reversal of Risk After Quitting Smoking.IARC Handbooks of Cancer Prevention, Vol. 11. p 11
  • [17]. Chezhian et al (2015); Exploring Factors that Influence Smoking Initiation and Cessation among Current Smokers;J Clin Diagn Res. 2015 May; 9(5): LC08–LC12
  • [18]. World Health Organization (WHO). The role of health professionals in tobacco control. Geneva: WHO, 2005.
  • [19]. Statistics on Smoking: England, 2014,
  • [20]. Centers for Disease Control and Prevention USA, Current Cigarette Smoking Among Adults in the United States,