Epidemiology of Lung Cancer

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Epidemiology of Lung Cancer

Postby Wilberforce » Tue Aug 02, 2016 7:37 pm

Epidemiology of Lung Cancer

By Dr Liji Thomas, MD

Lung cancer has become an epidemic since the 1930s. Identified risk factors include:
Host factors

Cigarette smoking

The incidence of lung cancer in the 20th century has largely mirrored the rise and fall in cigarette smoking.

The risk of lung cancer in smokers is ten times that of non-smokers. However, the incidence is expected to plateau in the next few decades because of a fall in the number of smokers.

Even so, lung cancer remains on the list as one of the major killers because of the sheer number of people who smoke, whether cigarettes, cigars, pipes or beedis (cigarettes made of unprocessed tobacco wrapped in leaves.)

With the advent of low-tar filter cigarettes, the type of lung cancer has shifted from mostly squamous cell to adenocarcinomas, which occur more peripherally. This is probably because of deeper and more frequent inhalations of smoke.

The lung cancer risk is determined by the number of cigarettes smoked, the duration of smoking and the age at which one starts smoking.

Family history

The risk of lung cancer rises 1.7-fold with a positive family history and the risk becomes 3.6-fold if two or more relatives had the disease.

Genetic factors

Familial clustering of lung cancer is associated with certain gene markers. For instance, the presence of TP53 variants in smokers increases the risk three-fold in comparison to non-smokers.

Another marker on chromosome 15 comprises three genes coding for nicotinic acetylcholine receptor subunits, which might increase the carcinogenic effects of nicotine or render the person more liable to nicotine addiction.

People with a single copy of the marker have a 30 percent higher risk, whereas two copies carry a 70-80 percent increased risk.

Menthol cigarettes

Menthol cigarettes date back to the 1920s, and are used most extensively by African-Americans.

The use of menthol cigarettes may lead to cigarette smoking, greater tendency to smoking addiction, and may also intensify exposure to toxins in cigarette smoke.

Estrogen-progestin formulations

Women who smoke in addition to taking estrogen plus progestin formulations, as opposed to estrogen alone, have a higher risk of lung cancer.

Processed meat

Cured meat, deep-fried meat and meat chili all increase the risk of lung cancer.

Alcohol intake

More than 30 g of alcohol a day is linked to a higher incidence of lung cancer.


Many people who have had radiotherapy to the chest or breast, or have undergone CT scans, may have a higher risk of lung cancer.


Lung cancer incidence increases with age.


Supplementation with high-dose ß-carotene increases the risk of lung cancer in smokers.


Lean people tend to have a higher risk of lung cancer. However, this is expected to be a confounding factor and low body weight is not thought to cause lung cancer. Instead, these populations tend to smoke and drink more, which may affect the risk.


Lung cancer is currently the leading cause of female deaths from cancer in the USA. More men than women still die from it, however, because of the higher incidence of smoking among males. This gap is rapidly narrowing at present.


African-American and white women have a similar lung cancer incidence. Among males, there is a 47 percent hike in both incidence and mortality among African-American men.

However, young African-Americans have begun to quit smoking in large numbers, which means this gap is likely to narrow over time.

Why more African-Americans with lung cancer die may reflect many factors, such as a later stage at diagnosis, the lack of high-quality specific treatment of lung cancer and possibly a greater susceptibility to lung cancer in response to smoking.

People of Native American, Asian and Hispanic origin have lower incidence and mortality rates in comparison to the communities mentioned above.

In Asian populations, the tumor characteristics, such as certain epidermal cell receptors, are beneficial in terms of survival and treatment response.

Socioeconomic Status

Poverty, low-income occupations, and lower education levels are associated with increasing lung cancer incidence rates all over the world, irrespective of the socioeconomic status of the country as a whole.

In China, for instance, there was an amazing six-fold variance between the lowest and highest income groups. Low socioeconomic class is an indicator for later diagnosis and a worse prognosis.

Confounding factors include increased smoking, impoverished or unhealthy diets, coupled with occupational or general exposure to other inhaled carcinogenic agents because of the poor socioeconomic profile.
Environmental factors

Passive smoking

Also called secondhand smoking, this term refers to the inhalation of smoke from another person’s cigarette, and is responsible for 1.6 percent of lung cancers.

Non-smokers who have a smoker at home have a 20 to 30 percent increased risk of lung cancer, compared to those without exposure to home smoking.

Children who lived with passive smoke had a 3.6 times higher incidence of lung cancer as adults.


Automobile emissions contain polycyclic aromatic hydrocarbons and metals such as arsenic, nickel, and chromium.

These metals are also present in many factories, and arsenic may be ingested in drinking water. They induce oxidation stress and inflammation, which leads to a hypercoagulable state as well as autonomic dysfunction, together contributing to up to 11 percent of lung cancers. Diesel exhaust also contains carcinogens.

In developed countries, indoor pollution by radon in the form of soil-derived gas increases the risk, especially with active or passive smoking. This is much higher in occupations such as uranium mining.

In poorer nations, indoor air is polluted by combustion products from unprocessed solid fuels, notably soft coal (a fossil fuel) and biomass fuels such as wood, used for cooking and space heating.

In China alone, 600 000 deaths from lung cancer over 30 years could be avoided by cutting solid fuel use in half.

Occupational risk factors

Exposure to carcinogens at the workplace, such as chrysotile asbestos and crystalline silica, as well as inhaled radioactive particles in uranium miners or nuclear plant workers, increases the incidence of lung cancers.

Coke oven workers inhale benzopyrene in tar and soot. All of the former work synergistically with tobacco smoke.

Geographic patterns

Within the USA, Kentucky has three times as many lung cancer patients for any given age group as Utah.

Lung cancer rates also shift across national boundaries, in both men and women. This is linked to smoking patterns, but with a 20-year lag period.

The incidence of smoking in both men and women is highest in Europe and North America but lowest in Africa.

Lung cancer not related to smoking is a unique feature of women’s health in China. Chinese women have high rates of lung cancers related to inhalation of fumes other than tobacco smoke, such as cooking gas or wood smoke.

In Chinese men, however, the rate of smoking has shot up ten-fold over a mere 40 years, with a corresponding and continuing increase in lung cancer incidence.

Thus a global view shows that tobacco smoking, and consequently, lung cancer, has shifted its focus from Western countries to the so-called Third World nations, and particularly to Asia.

Today, more lung cancers are diagnosed in these countries than in developed nations.
Protective factors

Food supplements

Fruits and vegetables contain antioxidants which protect against the development of cancers.

The most important among these are carotenoids, such as lutein, zeaxanthin, lycopene and ß-cryptoxanthin, as well as vitamin C and E.

Total carotenoid levels in diet and serum show a 20% to 30% lower risk from the highest to the lowest exposure groupings.

Isothiocyanates are thought to underlie the protective effect of cruciferous vegetable intake, such as cabbage, broccoli and Brussels sprouts. They may induce glutathione S-transferase which exerts anti-cancer effects.

However, cigarette smoke lowers the serum levels of most antioxidants.

Physical activity

People who participate in high to moderate exercisers have a 13-30% lower risk, even with heavy smoking.

Quitting smoking

Abstinence at any age lowers the risk and reduces the number of precancerous lesions. The effect increases with the duration of abstinence. The risk remains elevated above baseline for years, however.
Lung cancer in people who have never smoked

The incidence of lung cancer in never-smokers ranges from about 5 to 21 per 100 000 in the age group between 40 and 80 years.

In other words, about 20 percent of lung cancer patients, accounting for approximately 300 000 deaths, have never smoked.

The main risk factors include passive smoking, exposure to occupational or domestic carcinogens (including nickel, wood or soft coal smoke, chromates, arsenic and automobile exhaust), and radon exposure. However, these are absent in a significant proportion of cases.

More men than women, and more African-Americans, are affected, as are Asians living in Asia, in comparison to individuals of Caucasian origin.
Survival with lung cancer

The 5-year survival rate depends mostly on the stage at which the cancer is diagnosed, ranging from 52 percent to 4 percent in stage 1 and stage 4 respectively.

Reviewed by Yolanda Smith, BPharm

http://www.cancer.gov/types/lung/hp/non ... atment-pdq

Further Reading

Lung Cancer
Lung Cancer Causes
Lung Cancer Symptoms
Lung Cancer Diagnosis
Lung Cancer Treatments
Lung Cancer Research
Lung Cancer Questions
Lung Cancer Prevention
Lung Cancer Genetics
Lung Cancer Pathogenesis
What Causes Lung Cancer in Non-Smokers?
Lung Cancer Prognosis
Lung Cancer: Radiotherapy and Chemotherapy
Types of Lung Cancer Surgery
Lymph Nodes in Lung Cancer

Last Updated: Jul 26, 2016

http://www.news-medical.net/health/Epid ... ancer.aspx
• The Surgeon General has determined that there is no safe level of exposure to ambient smoke!

• If you smell even a subtle odor of smoke, you are being exposed to poisonous and carcinogenic chemical compounds!

• Even a brief exposure to smoke raises blood pressure, (no matter what your state of health) and can cause blood clotting, stroke, or heart attack in vulnerable people. Even children experience elevated blood pressure when exposed to smoke!

• Since smoke drastically weakens the lungs' immune system, avoiding smoke is one of the best ways to prevent colds, flu, bronchitis, or risk of an even more serious respiratory illness, such as pneumonia or tuberculosis! Does your child have the flu? Chances are they have been exposed to ambient smoke!
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Re: Epidemiology of Lung Cancer

Postby Wilberforce » Tue Aug 02, 2016 7:37 pm

What is Lung Cancer?
All About Lung Cancer

By Lynne Eldridge, MD - Reviewed by a board-certified physician.
Updated July 31, 2016
What is the Definition of Lung Cancer?

Lung cancer is a cancer (malignancy) that originates in the tissues of the lungs or the cells lining the airways (the bronchi). These cells begin as and look like lung cancer cells under the microscope, with the exception of changes that occur in the process of becoming cancerous.

If lung cancer spreads to other regions of the body, the cells are still lung cancer cells.

For example, if lung cancer spreads to the brain, cells taken from the metastasis (growth) in the brain would be identifiable as cancerous lung cancer cells under the microscope. In contrast, some tumors begin in other parts of the body and spread (metastasize) to the lungs. This is referred to metastatic cancer to the lungs and not lung cancer. An example would be a breast cancer which spreads to the lungs. This would not be called lung cancer, but rather "breast cancer metastatic to the lungs."
Anatomy of Lung Cancer

Lung cancer may occur anywhere in the lungs. The right lung is made up of 3 lobes and the left lung, 2 lobes.

When we take a breath of air, it enters through our nose and mouth, passes down through the trachea (the windpipe) and then into the mainstem bronchus. It then travels via a bronchus to either the right or the left lung. Once in the bronchi, the air then travels through increasingly smaller bronchioles and on into the alveoli - tiny air sacs in the lungs through which the exchange of carbon dioxide and oxygen takes place.

Capillaries (the smallest of blood vessels) surround the alveoli, receiving the oygen to carry it to the rest of the body. Cancer may occur anywhere in the respiratory system from the large bronchi, down to the alveoli.
How Common is Lung Cancer?

Lung cancer is the leading cause of cancer deaths worldwide million, with 1.8 million new cases being diagnosed yearly.

In the United States, lung cancer is the most fatal cancer in women, having passed up breast cancer in 1987 as the leading cause of cancer-related deaths. Lung cancer is also the most fatal cancer in men, killing more men than prostate cancer, pancreatic cancer, and colon cancer combined. Overall, 27 percent of cancer deaths in the U.S. are due to lung cancer. Described in another way, 433 people die from lung cancer each day. This is equivalent to a jumbo jet crashing each day of the year in the U.S. alone.

Before anyone dismisses these numbers as due to smoking alone, it's important to point out that even if smoking were banned today, we would still have lung cancer. Lung cancer in never smokers is the 6th leading cause of cancer deaths in the United States. In fact, the focus on smoking cessation as a way to treat lung cancer has, in some ways, overshadowed research looking into other causes.
Where is Lung Cancer Most Common?

Unfortunately, lung cancer is common throughout the world. Overall, the countries with the most lung cancer worldwide include Hungary,Serbia, and Korea.

Looking at lung cancer in women, however, the highest incidence is found in Denmark, followed closely by Canada and then the United States
Who Gets Lung Cancer?

The average age for lung cancer is 70, and 80 percent of people who develop lung cancer have smoked, but:

Lung cancer occurs in women - Women are actually much more likely to die from lung cancer than breast cancer, and the incidence of lung cancer in women has almost caught up with that in men. In 2016 it's estimated that 85,920 men and 72,160 women will die from lung cancer. In comparison, 40,450 women will die from breast cancer.

Lung cancer occurs in non-smokers - And while lung cancer in men who have smoked is decreasing, lung cancer in non-smokers is increasing. It's estimated that 20 percent of women who develop lung cancer in the U.S. have never smoked, and that number increases to 50 percent worldwide.

Lung cancer occurs in young adults - It's estimated that 13.4 percent of lung cancers occur in adults under the age of 40. While this number may seem small, when compared to the incidence of lung cancer overall, it is not. Calculating this out, around 21,000 young adults will die from lung cancer this year (again comparing this to 40,450 breast cancer deaths for women of all ages.) In addition, women are more likely than men to develop lung cancer at a young age, and lung cancer in young adults is increasing.
Types of Lung Cancer

There are 2 primary types of lung cancer:

Non-small cell lung cancer is most common, being responsible for 80 to 85 percent of cancers. This is the type of lung cancer more commonly found in non-smokers, women, and young adults.
Small cell lung cancer is responsible for around 15 percent of lung cancers. These lung cancers tend to be aggressive and may not be found until they have already spread (especially to the brain.) They usually respond fairly well to chemotherapy but have a poor prognosis.

Nonsmall cell lung cancer is further broken down into 3 types:

Lung adenocarcinoma - Lung adenocarcinoma is responsible for half of non-small cell lung cancers and is currently the most common type of lung cancer. It is also the most common type of lung cancer found in women, young adults, and in people who do not smoke.
Squamous cell carcinoma of the lungs - Squamous cell lung cancer was once the most common type of lung cancer, but its incidence has decreased in recent years. Part of the thought is that the addition of filters to cigarettes created this shift. Squamous cell cancers tend to occur in or near the large airways - the first place exposed to smoke from a cigarette. Lung adenocarcinomas, in contrast, are usually found deeper in the lungs, where smoke from a filtered cigarette would settle.
Large cell lung cancer - Large cell carcinomas of the lungs tend to grow in the outer regions of the lungs. These are usually rapidly growing tumors that spread quickly.

Other, less common types of lung cancer include carcinoid tumors and neuroendocrine tumors.
Signs and Symptoms of Lung Cancer

Having an awareness of the early signs and symptoms of lung cancer is a must for everyone for two reasons:

There is not a screening test available for everyone so the only way that most people have to find these cancers early—when they are most treatable—is knowing the signs. Recent research tells us that the majority of people in the United States are not familiar with these symptoms.
Because lung cancer is common. As noted earlier, lung cancer is the leading cause of death in both men and women and anyone who has lungs is at risk.

Overall, the most common symptoms include:

Shortness of breath with activity
A persistent cough
Coughing up blood
Unexplained weight loss
Chest pain

Of note is that the types of lung cancer have been changing over the years, and with that, the most common symptoms. In the past, lung cancers such as squamous cell carcinoma and small cell lung cancer were most common. These cancers tend to grow near the large airways of the lungs and cause symptoms early on - commonly a cough and coughing up blood. Now, lung adenocarcinoma, a tumor which tends to grow in the outer regions of the lungs is most common. These cancers tend to grow for a long time before causing symptoms which may include mild shortness of breath, subtle weight loss, and a general sense of being unwell.
Diagnosis and Staging

A combination of imaging studies including CT, MRI, and PET scans may be used to diagnose lung cancer. In addition, a lung biopsy is usually needed to determine the type of lung cancer.

Careful staging - figuring out how extensive a lung cancer is - is important in designing a treatment regimen. Non-small cell lung cancer is broken down into five stages: stage 0 to stage IV. Small cell lung cancer is broken down into only two stages: limited stage and extensive stage.
Causes of Lung Cancer

Certainly, smoking is an important cause of lung cancer, but noting the statistics above, there are other important causes of lung cancer as well.

Radon exposure in the home is the second leading cause of lung cancer and the most common cause in non-smokers. Any home in the United States (or anywhere in the world for that matter) is potentially at risk, and the only way to know is to do radon testing. Radon is an odorless, colorless gas that results from the normal decay of uranium in the soil beneath our homes. It's estimated that 27,000 radon-induced lung cancer deaths occur yearly in the U.S. alone and that 15 percent of cancers worldwide are related to radon exposure.

Another 7,000 lung cancer deaths occur each year due to secondhand smoke. Other causes and possible causes include occupational exposures, air pollution, wood smoke and cooking with poor ventilation. Recently it's been found that human papillomavirus (HPV)—the virus which causes cervical cancer—is associated with some lung cancers, though it's not at all certain if this may be a factor in the cause.
How Does Lung Cancer Begin?

Lung cancer usually begins several years before it causes symptoms and is diagnosed. Cells in the lungs may become cancer cells after going through a series of mutations which transform them into cancer cells. Gene mutations - or changes in the DNA of the cells - may be inherited (as a hereditary predisposition) or acquired (damaged as the result of exposure to carcinogens (cancer-causing substances) in the environment. This accumulation of mutations is one of the reasons for a common finding with lung cancer: many people develop lung cancer though they have never smoked, and some people smoke their whole life and never develop lung cancer.

Lung cancer begins - a tumor originates - when a mass of cancer cells becomes immortal in a way; cells dividing and multiplying out of control. Our normal cells are regulated by a series of checks and balances.
How Does Lung Cancer Grow and Spread

One of the differences between benign lung tumors and lung cancer, as noted, is that lung cancer cells have the ability to break off and spread to other regions of the body. This spread, in fact, is the cause of most cancer deaths. One of the differences between cancer cells and normal cells is that cancer cells lack "stickiness." Normal cells produce substances that cause them to stay together. Without this stickiness, lung cancer cells can travel and grow in other regions, as well as invade nearby structures.

There are 4 primary ways in which lung cancers spread. It can "invade" tissues locally. Unlike benign tumors which may push up against nearby tissues, cancers actually penetrate nearby tissues. This is the reason for the name "cancer" which is derived from the word crab; cancer can send crablike extensions into nearby tissues.

Lung cancer cells can also break away and spread through either the bloodstream or the lymphatic system to distant sites. In recent years, it's also been found that lung cancer may travel and spread through the airways in the lungs.
Does Lung Cancer Ever Just Go Away?

Though it is very rare, lung cancer does, in some cases, just go away. This phenomenon is referred to as spontaneous remission of cancer. Researchers are tapping into this discovery to learn how our immune systems ordinarily function to remove cancer cells, and design treatments based on this principle.
Lung Cancer Screening

Until recently, we did not have a screening test for lung cancer but that has changed. It's important to note that chest x-rays are not an adequate screening test as these fail to pick up lung cancers at a stage early enough to improve survival. Lung cancer CT screening is now recommended for people who:

Are between the ages of 55 and 80
Smoked for at least 30 pack-years (a pack year is calculated by multiplying the number of packages of cigarettes smoked daily times the number of years smoked)
Continue to smoke or quit in the past 15 years

For people with other risk factors, such as a family history of lung cancer, a history of COPD, or other risk factors for lung cancer , screening may also be considered. It's estimated that if everyone who qualified for screening undewent these tests, the mortality rate from lung cancer could be decreased by 20 percent.
Where Does Lung Cancer Spread?

The most common sites of lung cancer metastases include the brain, the bones, the liver, and the adrenal glands. Some types of lung cancer, for example small cell lung cancer, are often diagnosed after the cancer has already spread. Lung cancer is also somewhat unique in that it can spread to the bones of the hand and feet.
Lung Cancer Treatments

Treatment options for lung cancer have improved significantly in recent years. These include:

Surgery - There are several types of lung cancer surgery which may be done, depending on the size and location of a tumor.
Radiation therapy - Radiation therapy may be given as an adjunct to surgery, to decrease pain or airway obstruction due to a cancer, or in high doses to a localized region in an attempt to cure cancer (stereotactic body radiotherapy.)
Chemotherapy - Chemotherapy usually uses a combination of medications to treat lung cancer.
Targeted therapies - Everyone with lung cancer should have molecular profiling (gene testing) done on their tumors. Targeted therapy drugs are currently available for people with EGFR mutations, ALK rearrangements, and ROS1 rearrangements.
Immunotherapy - In 2015, two immunotherapy drugs were approved for the treatment of lung cancer. In some cases, these drugs have resulted in long-term survival even for those with the advanced stages of lung cancer.

A relatively new type of cancer care is termed palliative care. Palliative care is care designed to address the full spectrum of medical needs for people with cancer, including physical, emotional, and spiritual support. Unlike hospice care, palliative care can be used for anyone, even if you have a cancer which is considered curable. Early studies have found that, in addition to improving the quality of life for people, this care may also improve survival.

Alternative forms of treatment such as acupuncture may help people cope with symptoms that come with cancer and cancer treatments. These integrative treatments are now available at many cancer centers.

integrative treatments
If You Have Recently Been Diagnosed With Lung Cancer

If you have only recently been told you have lung cancer you are probably very frightened and not a little overwhelmed. Learning as much as you can about your cancer can help you feel more in control of your treatment, and help you play an active role in your care. Research your cancer. Reach out to friends and family and allow them to help you with things you can delegate. Learn how to advocate for yourself as a cancer patient.

You may feel isolated as you face something nobody in your group of loved ones can understand. Participating in cancer support groups and communities may allow you to connect with others who are walking a similar road. These groups are also a good way to stay updated on the latest research about lung cancer.

Take a moment to pamper yourself, and forgive yourself if you are feeling out of sorts. Nobody really knows how they will feel until they are diagnosed The emotions you experience may span the spectrum from sadness to anger, to intense anxiety—sometimes in just a matter of minutes. Check out these first steps for when you are newly diagnosed.
If Your Loved One Has Lung Cancer

If it is your loved one rather than yourself who has been diagnosed with lung cancer, it can sometimes be even harder to cope. On top of the diagnosis, you may feel totally helpless as to what to do. At the same time that you are struggling with fears and sadness, the emotions your loved one is experiencing can be confusing and even heartbreaking. Check out these thoughts about "when your loved one has lung cancer" in which people who have lived with the disease share what they wish their loved ones had known.
A Word From Verywell

The face of lung cancer is changing. For many years people living with lung cancer have had to cope with not only the stigma of lung cancer being a "smoker's disease" but the myth that it is uniformly fatal. This stigma is changing as the public becomes more aware that anyone with lungs can get lung cancer. The survival stigma is changing as well, as the public is learning of new newer and better treatments that have recently ?been approved. In addition to the many new treatments approved in the past few years alone, there are over 100 medications being studied in clinical trials for lung cancer.

We still have a way to go, but many people are surviving—and thriving—while living with this disease. There is a lot of hope.


American Cancer Society. Cancer Facts and Figures 2016. Accessed 07/20/16. http://www.cancer.org/research/cancerfa ... gures2016/

American Lung Association. Lung Cancer Fact Sheet. Accessed 07/22/16. http://www.lung.org/lung-health-and-dis ... sheet.html

Pass, J., Carbone, D., Johnson, D. et al. Principles and Practice of Lung Cancer. 4th Ed. Williams and Wilkins: 2010.

• The Surgeon General has determined that there is no safe level of exposure to ambient smoke!

• If you smell even a subtle odor of smoke, you are being exposed to poisonous and carcinogenic chemical compounds!

• Even a brief exposure to smoke raises blood pressure, (no matter what your state of health) and can cause blood clotting, stroke, or heart attack in vulnerable people. Even children experience elevated blood pressure when exposed to smoke!

• Since smoke drastically weakens the lungs' immune system, avoiding smoke is one of the best ways to prevent colds, flu, bronchitis, or risk of an even more serious respiratory illness, such as pneumonia or tuberculosis! Does your child have the flu? Chances are they have been exposed to ambient smoke!
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