What is the most common type of lung cancer in non-smokers
about health
Lynne Eldridge MD
What type of lung cancer is most common in non-smokers?
There are a few parts to this answer, but first, since you asked this question, its important to say that understanding that lung cancer occurs in non-smokers means youre a step ahead of the crowd.
Lung cancer not only occurs in people who have never smoked, but lung cancer in never smokers is the 6th leading cause of cancer deaths in the United States.
When discussing this question it can help to distinguish statistics and studies which speak of non-smokers vs those that refer to never smokers. The category of non-smokers includes both never smokers and people who smoked at one time but have now quit (former smokers.) The term never smokers refers to people who have smoked 100 cigarettes or less during their lifetime.
At the current time, roughly 10-15% of people who develop lung cancer are never smokers, roughly 39% are active smokers, and 49-54% are former smokers. Added together, the majority of people are non-smokers at the time of a lung cancer diagnosis.
To answer this question it helps to break lung cancer down step by step into the different types.
Non-Small Cell Lung Cancer vs Small Cell Lung Cancer
There are 2 major types of lung cancer, non-small cell lung cancer and small cell lung cancer. These types are named by the appearance of the cancer cells under the microscope, with small cell cancers being composed of, not surprisingly, small, abnormal appearing lung cells.
Non-small cell lung cancer accounts for 85-90% of lung cancers, and is the most common major type of lung cancer found in non-smokers. It is also, due to numbers, the most common major type of lung cancer found in people who smoke. Small cell lung cancer accounts for 10-15% of lung cancer and is much more strongly associated with smoking. Its thought that only around 1% of people who develop this type of lung cancer have never smoked.
Types of non-small cell lung cancers
Non-small cell lung cancer is further broken down into 3 different types:
Lung adenocarcinoma is the most common type of non-small cell lung cancer, and is the most common type of lung cancer found overall in both non-smokers and smokers. It is also by far the most common type of lung cancer in women, and young adults with lung cancer.
Lung adenocarcinoma accounts for 30% of lung cancers in male smokers, and 40% of female smokers. In contrast, this type of tumor accounts for 60% of lung cancers in non-smoking men, and 80% of lung cancers in non-smoking women.
The other forms of non-small cell lung cancer include squamous cell carcinoma of the lungs which accounts for 25-30% of non-small cell lung cancers, and large cell lung cancer which is present in 10-15% of non-small cell lung cancers. These cancers are both much more common in people who have smoked. Not all cancers are strictly defined by one of these subtypes, and its possible for a lung tumor to have regions of lung adenocarcinoma as well as squamous cell carcinoma, as well as other combinations of tumor characteristics.
Why would smokers and non-smokers develop different types of lung cancer?
One possible difference in the types of lung cancer seen in smokers and non-smokers may be related to the particular areas of the lung most affected by the lung cancer carcinogens in question, whether this is tobacco smoke, radon gas, occupational chemicals, or other exposures. It may also be related to the type of damage (DNA mutations) caused by the particular carcinogens. At this time this question remains mostly unanswered. Its interesting to point out that with the addition of filters to cigarettes, the most common types and locations of lung cancers changed. Years ago cancers such as squamous cell non-small cell lung cancer and small cell lung cancer were more common. These cancers tend to begin in the larger airways entering the lungs (the bronchi.) After filters were adopted, lung adenocarcinoma became much more common. These cancers tend to arise in and near the smaller airways in the periphery of the lungs.
Why is this information
important?
Lung cancer in non-smokers is a different disease in many ways. In addition to the types of lung cancer, there are also differences between non-smokers and smokers with regard to which treatments are most effective, and even survival rates.
Symptoms of Lung Cancer in Non-Smokers
Why do they differ from those in smokers?
Lung cancer in nonsmokers appears to be increasing, and, at the present time anyway, we dont have a screening test for nonsmokers.
Symptoms of lung cancer in non-smokers may be different from lung cancer in people who smoke. Sometimes the symptoms may be more subtle, such as shortness of breath with activity, or hard to define, such as fatigue. What are some common symptoms of lung cancer in non-smokers and why might they be different from those in smokers?
As a quick aside, talking about lung cancer in non-smokers is more important than ever. Currently 20% of women who develop lung cancer in the United States are lifelong non-smokers. In addition, the majority of people, both men and women, who develop lung cancer at this time are former, not current smokers.
Why might symptoms of lung cancer in non-smokers differ from those in people who smoke?
One of the reasons that the symptoms of lung cancer in non-smokers and smokers may differ is that the most common types of lung cancer vary depending upon smoking status - and different types of lung cancer tend to have different symptoms.
Another reason may be that women who develop lung cancer are more likely than men to have never smoked - and the types of lung cancer found commonly in women and men can differ.
Lung Cancer in Women
Lung Cancer in Men
Symptoms of lung cancer in non-smokers related to lung cancer type
There are two main types of lung cancer. Non-small cell lung cancer accounts for roughly 80% of lung cancers and is broken down into three subtypes that vary among non-smokers and people who smoke.
Non-invasive painless treatment with precise accuracy for tumors
Small cell lung cancer is responsible for around 20% of lung cancer, and is found more commonly among people who have smoked.
Non-small cell lung cancers
The three main types of non-small cell lung cancer include:
Lung Adenocarcinoma
Squamous Cell Carcinoma
Large Cell Carcinoma
The most common type of non-small cell lung cancer in non-smokers is adenocarcinoma. Lung adenocarcinomas tend to grow in the outer regions of the lungs. Due to their location away from the large airways, these tumors often grow quite large or spread before they cause any symptoms. Initial symptoms may include:
Shortness of breath - The gradual onset of shortness of breath may first be dismissed as being due to age or inactivity
Back and shoulder pain - Due to pressure on nerves caused by the tumor
Chest pain that worsens with a deep breath (pleuritic chest pain) - Tumors near the outer regions of the lungs can irritate the membranes that line the lungs. This can cause pain with breathing
Fatigue
Symptoms due to lung cancer spread (metastasis) -- Common areas that lung cancer spreads to include bones and the brain
In contrast, squamous cell carcinoma of the lungs is much more common in people who have smoked.
These tumors tend to grow in or near the large airways of the lungs and often cause symptoms early on in the disease.
These symptoms may include coughing up blood, a persistent cough, and infections (such as recurrent bronchitis or pneumonia) due to obstruction of the airways by the tumor.
Small cell lung cancers
Small cell lung cancers occur more often in men and people who smoke.
These tumors frequently begin near the large airways causing a persistent cough or coughing up blood, and spread early, often to the brain.
Lung Cancer Types
One form of non-small cell lung cancer is seen more commonly in young women and people who have never smoked, and appears to be increasing in incidence in the United States. Bronchioloalveolar Carcinoma (BAC) may cause symptoms similar to other lung cancers, but it has also been coined the masquerader. It is not uncommon for BAC to be misdiagnosed
first as pneumonia or other lung disease.
Common symptoms of lung cancer in both non-smokers and smokers
It is helpful to review common symptoms of lung cancer that are found in both non-smokers and in people who smoke. These may include:
A persistent cough
Coughing up blood
Wheezing
Shortness of breath
Hoarseness
Repeated lung infections such as bronchitis or pneumonia
Less common symptoms of lung cancer in non-smokers
As noted above, the most common types of lung cancer in smokers tend to grow near the central airways. These tumors tend to cause symptoms earlier on in the course of the disease, with symptoms related to the presence of the tumor near the airway.
As such, coughing up blood, obstruction leading to lung collapse (atelectasis), and coughing might be seen earlier in lung cancers found in smokers than they would be in non-smokers.
Another group of symptoms that are seen occasionally with lung cancer is something called paraneoplastic syndrome. Paraneoplastic syndrome is a group of symptoms caused by hormone-like substances
secreted by tumors, and is seen most often with small cell lung cancers, squamous cell lung cancers and large cell carcinomas - cancers that are found more often in people who smoke.
Paraneoplastic symptoms may include an elevated calcium level in the blood, a low sodium level, weakness in the upper limbs, loss of coordination and muscle cramps among other
symptoms.
Source: about health
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