TOPIC: Lung Cancer occurrence in Never-Smokers: an analysis of 13 cohort and 22 cancer registry studies

Each year, over 170,000 Americans develop lung cancer, and approximately ten per cent of lung cancers, or 17,000 cases, occur in non-smokers. Although not every non-smoker suffering from lung cancer will have an identifiable risk factor for development of the disease, a number of conditions and circumstances have been identified that will increase a non-smoker’s chance of developing lung cancer. At the end of the 20th century, lung cancer had become one of the world’s leading causes of preventable death. It was a rare disease at the start of that century, but exposures to new etiologic agents and an increasing lifespan combined to make lung cancer a scourge of the 20th century. While tobacco had been widely used throughout the world for centuries, the present pandemic of lung cancer followed the introduction of manufactured cigarettes with addictive properties, which resulted in a new pattern of sustained exposure of the lung to inhaled carcinogens.

The article is an analysis of occurrence of lung cancer in non-smokers among men and women between 40-69 years who are African-Americans, Asians and European descent, the data were abstracted from 10 countries wherein women have a low prevalence of smoking. The analysis aims to measure how frequently lung cancer occurs in or kills lifelong non-smokers -- it did not examine why. As such, the analysis did not examine second-hand smoke and other known risk factors of lung cancer.
The analysis result shows that 1) Men had higher death rates from lung cancer than women in all ages and racial groups studied; 2) male and ‘female incidence rates were similar when standardized across all ages 40+ years, although with some variation with ages; 3) African Americans and Asians living in Korea and Japan but not in US had higher death rates from lung cancer than individuals of European descent; 4) no temporal trends were seen when comparing incidence and death rates among women age 40-69 years old during the 1930’s to contemporary populations where few women smoke, or in temporal comparisons of never-smokers in two large American Cancer Society cohorts from 1959 to 2004; 5) lung cancer incidence rates were higher and more variable among women in East Asia than in other geographic areas with low female smoking. These results were based on the analysis of 13 Cohorts and 22 cancer registry studies.
The strength of the analysis is its ability to compare incidence and death rates from multiple sources in well-defined populations from different countries, time periods and demographic subgroups. However there are some limitations mentioned by the authors that needs further research, some of these limitations are 1) the analyses of the respondents who came from different countries has limited data which could pose errors in comparing the number of morbidity and mortality rate; 2) the incidence data were also limited for Asian men and women and African American women, even in individuals of European descent. In addition to this incomplete records and unrecorded incidence of lung cancer occurrence significantly affected the results of the analysis. Lastly the authors did not attempt to identify specific exposure that may contribute to occurrence of lung cancer.
REFERENCE:
1. Alberg, A., Samet, J. (2003). Epidemiology of Lung Cancer. Vol. 123, no. Retrieved June 21, 2009, from http://www.chestjournal.org/content/123/1_suppl/21S.full
2. Stoppler, M. Lung Cancer. Retrieved June 21, 2009, from http://www. Medicinennet.com/lung_cancer/article.htm

it is estimated that 10-15% cases of lung cancer never smoked. and most commonly in women. it is believed that the major cause of this is the role of second hand smoke.limiting this exposure to these reduces the risk of lung cancer

other causes of lung cancer:

-radon embedded dirt in residential homes
-estrogen also plays a factor in the development of lung cancer. Studies suggest that blocking estrogen may prevent lung cancer from growing.
-genetics, Researchers have found genes that can greatly increase the risk factor for lung cancer development. This finding may explain why people who smoke 3 packs a day may never develop lung cancer, while one who only smokes 5 a day develops it. It may be a matter of who is carrying this gene.

lisa fayed(2007,may 4) Can Non -Smokers Develop Lung Cancer?
http://cancer.about.com/od/lungcancer/a/nonsmokers.htm

Passive smokers or secondhand smokers are believed to also be at risk for lung cancer as that of the firsthand smokers. Men and women of different age groups are at risk for lung cancer. Their genes, hormones and lifestyle may affect the occurrence of lung cancer.

I have much concern for children whose parents are smokers. This exposure increases the risk of upper and lower respiratory tract infections such as bronchitis and pneumonia. It may also worsen the symptoms of other respiratory tract infections. Passive smoke also increases the prevalence of fluid in the middle ear, a sign of chronic middle ear disease. If these cases occur. children will be greatly affected and may be hospitalized.

Smoking then should be prevented so the risk for lung cancer will be minimized.

http://www.epa.gov/iaq/ets/pubs/etsfs.html

Passive smoking is the inhalation of smoke from another’s smoking. Studies have consistently shown a significant increased in the relative risk of acquiring lung cancer among those who are exposed to secondhand tobacco smoke, especially spouses of smokers and never smokers at the workplace. The risk of lung cancer for passive smokers goes up the more cigarette smoke they are exposed to. Studies also revealed that the epidemiological and biochemical evidence on exposure to environmental tobacco smoke provides compelling confirmation that breathing other people’s tobacco smoke is a cause of lung cancer. Carcinogens in environmental tobacco smoke are inhaled and pass into the blood. Experimental exposure of non-smokers to tobacco smoke increased the urinary concentration of a tobacco specific carcinogen, and non-smokers exposed to environmental tobacco smoke have raised blood concentrations of tobacco specific carcinogen. Aside from passive smoking, there are other factors that cause lung cancer to non-smokers. These are radon gas, asbestos, viruses, genetic risk and other contact to some chemicals.

I conclude that involuntary smoking is a cause of lung cancer in never-smokers. So I agree that cigarette should be stop to prevent the risk of lung cancer.

Reference:

Hackshaw, A.K., Law, M.R., Wald, N.J.The accumulated evidence on lung cancer and environmental tobacco smoke. BMJ, 315:980-988. Retrieved October 18, 1997 from
http://www.bmj.com/cgi/content/full/315/7114/9

Many people are stunned because she was not a smoker and her death came so suddenly. There are still an increasing number of patients who do not have a smoking history, so-called 'never smokers'. While cigarette smoking is an undisputed cause of lung cancer, not all cases of lung cancer occur in smokers or former smokers. Although not every non-smoker suffering from lung cancer will have an identifiable risk factor for development of the disease, a number of conditions and circumstances have been identified that will increase a non-smoker's chance of developing lung cancer.

What are the risk factors for lung cancer?

Gender: Unfortunately, women seem to be more vulnerable to lung cancer. Research has shown that female smokers are more susceptible to the cancer-causing chemicals found in cigarettes. In another study, a gene linked to abnormal lung cancer cell growth was found to be more active in women than in men. It did not matter whether the women smoked or not.

A family history of lung cancer: Evidence suggests that there is a lung cancer gene which predisposes offspring to develop lung cancer. However, the evidence is far from conclusive as the situation is made difficult by the fact that offspring of smokers have been exposed to a smoking environment since childhood and would therefore have a greater risk for developing the disease.

Scarring from previous lung disease : Scarring in lungs caused by tuberculosis or other lung disease can be a risk factor for lung cancer.

Second-hand smoke: Exposure to second-hand smoke has been shown to be a definite risk factor. Your risk increases by 30 percent from daily exposure to second-hand smoke. This is probably the most significant risk factor for lung cancer in non-smokers.

Exposure to radon: Radon is an odorless gas than can seep out of the soil into buildings. Worse yet, the gas can seep from the soil into water near residential communities. Radon has been implicated as a potential cause of lung cancer.

Air pollution: Long-term occupational exposure to diesel exhaust fumes may increase lung cancer risk by 47%. Air pollution in general is a risk factor in the general population.

Past Cancer Treatment: Researchers in Sweden who looked at the medical records of 140,000 breast cancer patients found that there was an increase of lung cancer 5 to 20 years after breast cancer treatment. Suspicion is that radiotherapy in the chest area may have made the lungs more susceptible to the disease.

Estrogen Replacement fuel the growth of non small-cell lung cancer.

What preventative measures can we take?

Diet: An apple a day may keep lung cancer away. A Finnish study suggests that apples not only keep doctors away, but provide protection for the lungs as well. This study found that people who ate the most apples were 58 % less likely to develop lung cancer. Other studies suggest that lung cancer risk is lower among smokers and non smokers who ate at least 5 servings of vegetables and fruits daily.

Beta Carotene: A high intake of beta carotene compounds can lower your lung cancer risk; however, studies also show that the beta carotene is only effective when the compounds are ingested from whole foods such as peaches, melon, carrots, mangoes, dark leafy vegetables, squash etc. The opposite effect seems to take place with beta carotene supplements. A Finnish study reported 18% more lung cancer cases among heavy smokers who took beta carotene supplements. And a National Cancer Study on the effects of vitamin A and beta carotene was halted because smokers taking the supplements had 28% more lung cancer than those taking a placebo.

Selenium and Vitamin C: Taking selenium supplements on a long- term basis has been shown to decrease the incidence of lung cancer. In one study, people taking 55-200 mcg of the mineral daily had a 46% lower rate of lung cancer. As well, studies indicate that people who take less than 90 mg of vitamin C on a daily basis may have a 90% higher risk of lung cancer than those who take 140mg or more.

Avoid second-hand smoke and check your house for radon.

Quote:

There are never guarantees in life, but it makes perfectly good sense to take some preventative measures as these can not only improve your overall quality of health and life but also prevent lung cancer.

REFERENCES:
1. www.medicinenet.com/script/main/art.asp?articlekey=53012
2. cancer.about.com/od/lungcancer/a/nonsmokers.htm

You have mentioned in your article that,

Quote:

"Although not every non-smoker suffering from lung cancer will have an identifiable risk factor for development of the disease, a number of conditions and circumstances have been identified that will increase a non-smoker’s chance of developing lung cancer."

Certainly, a non-smoker’s chance of developing lung cancer would increase through a number of conditions and circumstances.
The question is, “what are these conditions and circumstances?”

In the study of the World health organization, I have read and it states that, “Involuntary smoking involves exposure to the same numerous carcinogens and toxic substances that are present in tobacco smoke produced by active smoking, which is the principal cause of lung cancer.

More than 50 studies of involuntary smoking and lung cancer risk in never-smokers, have been published during the last 25 years. These studies have been carried out in many countries. Most showed an increased risk, especially for persons with higher exposures.

This evidence is sufficient to conclude that involuntary smoking is a cause of lung cancer in never-smokers. The magnitudes of the observed risks are reasonably consistent with predictions based on studies of active smoking in many populations."

Secondhand smoke is a known carcinogen (a substance that causes cancer). Many research studies show that inhaling secondhand smoke causes lung cancer in adults who do not smoke. Approximately 3,000 nonsmokers die of lung cancer each year.
The Surgeon General estimates that living with a smoker increases the chance of getting lung cancer by up to 30%. And a recent large study showed that the risk of lung cancer is nearly twice as high when the first exposure to secondhand smoke occurs before age 25, compared with later in life. (American Society of Clinical Oncology, 2009)


References:
World Health Organization, International Agency For Research of Cancer,(2004), Tobacco Smoke and Involuntary Smoking, volume 83, Volume 83 - Chapter 5.2: Human carcinogenicity data, http://www.greenfacts.org/en/tobacco/3-tobacco-smoking/6-passive-smoking-cancer.htm#1p0

American Society of Clinical Oncology ( 2009), Second Hand Smoke and Cancer,www.cancer.net

Secondhand smoke is also known as environmental tobacco smoke (ETS) or passive smoke. It is a mixture of 2 forms of smoke that comes from burning tobacco:
• sidestream smoke: smoke that comes from the end of a lighted cigarette, pipe, or cigar
• mainstream smoke: smoke that is exhaled by a smoker

When non-smokers are exposed to secondhand smoke it is called involuntary smoking or passive smoking. Non-smokers who breathe in secondhand smoke take in nicotine and other toxic chemicals just like smokers do. The more secondhand smoke you are exposed to, the higher the level of these harmful chemicals in your body.
Non-smokers who are exposed to second-hand smoke are more at risk because the particles in the exhaled smoke are smaller. They reach deeper into the lungs of the passive smokers.
The unfortunate non-smoker exposed regularly to second-hand smoke, is prone to specific health risks which include:
Increased risk of heart disease
Increased risk of lung cancer
Increase frequency of respiratory infections and asthmatic bronchitis in infants and children
chronic irritation of the eyes, nose and throat especially among children



American Cancer Society
http://www.cancer.org/docroot/PED/content/PED_10_2X_Secondhand_Smoke-Clean_Indoor_Air.asp


http://www.doh.gov.ph/programs/tobacco

Passive smoking the inhalation of smoke from another's smoking is a cause of lung cancer in nonsmokers. A passive smoker can be classified as someone living or working with a smoker as well. Studies from the U.S., Europe, the UK, and Australia have consistently shown a significant increase in relative risk among those exposed to passive smoke. Recent investigation of sidestream smoke suggests that it is more dangerous than direct smoke inhalation.

http://en.wikipedia.org/wiki/Lung_cancer

Regarding with the post that lung cancer in more prevalent in women, I found that there is a study published in a journal by PLos Medicine revealed that for those who are never-been smokers tat men are more rampant in men than in women among African American living in Korea and Japan while in the oppsition with the results in East Asia where women outnumbered men. But in other places in the world the rate seems to be just balanced among men and women.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2531137&tool=pmcentrez

Never-smokers with lung cancer constitute an understudied and under-represented subset of patients. Although there have been hints that never-smokers can be afflicted with lung cancer, especially among Asian Chinese women, it is only recently that attention has turned towards this much ignored group of patients. Sparking the attention was the finding that somatic mutations of the epidermal growth factor receptor (EGFR) were consistently more common among lung tumours of never-smokers, and that these mutations could possibly explain the higher response rates to single agent gefitinib. (Toh and Lim, 2006)

The study is interesting in way that it deals about the Lung Cancer occurrence of Never-smokers. Initially, I was thinking about these “never-smokers as those who did not even have one cigarette in their lifetime. It’s surprising to know the facts on how such disease occur in these people. But as I read through, I see that it encompasses those people who never smoke and those who did smoke but on the limits of a hundred cigarettes in their lifetime only.

It is somewhat bothering to know that lung cancer occurrence among these lifelong nonsmokers is 2-3 times higher in Asians considering we are in the same race. And smokers on the other hand, would have 15 times probability to die of the disease itself. With that in mind, this study would help us do the initiative to promote non-smoking in our own areas. It is for the reason that whether or not you are a smoker, occasional smoker, or previously a smoker, you still have the likelihood of having lung cancer. These lifelong nonsmokers also have this job in hand so as to change the risk of it in due time.

It is noteworthy to state that: “the person’s cumulative risk of developing lung cancer is related to how much they smoke, to how many years they are a smoker-if they give up smoking-to the age at which they give up smoking”.

REFERENCE:
Toh C., Lim W, (2006) “Lung Cancer in Never Smokers” for the Department of Medical Oncology, National Cancer Centre, SIngapore

cliff,

i like ur topic, i have heard in the news few weeks back that there are three subcategory in which one can acquire cancer, first is the primary smoker which is the active one, next is the secondary the one we knew as passive and guess what my third or tertiary pala , since i studied in the province maybe my teacher forgot to include this to her lectures, anyways the tertiary, like for example i smoke in the kitchen, after i smoke those stain that are left behind in the plates, wall, kitchen utensils can also be a circumstance for him to develop lung cancer. so why not smoke, as the saying goes you smoke u die u don't smoke u still die forgot where i heard the news from.