Type of Lung Cancer

Lung cancer or lung carcinoma is the uncontrolled division of epithelial cells which line the respiratory tract there are two main categories of lung cancer small cell and non small cell

which depend on the type of epithelial cell that's dividing both types can be fatal especially if

the cancerous cells aggressively spread and establish secondary sites of cancer and other tissues
the major cause of lung cancer is smoking tobacco products and it's contributed to the deaths

of millions of people including famous individuals like Walt Disney and Claude Monet now air

enters the respiratory tract through either the nose or mouth and flows down the trachea which divides into the right and left bronchi each bronchi enters its respective lung at the

hilum or the root of the lung the bronchi then divides into lobar bronchi which divided into

segmental bronchi then into sub segmental bronchi which further branched to form conducting

bronchioles and then respiratory bronchioles which end with small sacs called alveoli that are

surrounded by capillaries which is where gas exchange happens lining these Airways are several

types of epithelial cells which serve multiple functions these include ciliated cells that have

hair like projections called cilia that worked to sweep foreign particles and pathogens back to

 the throat to be swallowed another type called goblet cells which are called that because they

 look like goblets secrete mucin to moisten the airways and trap foreign pathogens there are also basal cells that are thought to be able to differentiate into other cells in the epithelium

club cells that act to protect the bronchial epithelium and neuro endocrine cells that secrete

hormones into the blood in response to neuronal signals cells can become mutated because of environmental or genetic factors a mutated cell becomes cancerous when it starts to divide

uncontrollably as cancer cells start piling up on each other they become a small tumor mass

and they need to induce blood vessel growth called angiogenesis to supply themselves with

energy malignant tumors are ones that are able to break through the basement membrane

some of these malignant tumors go a step further and detached from their basement

membrane at the primary tumor site and then enter nearby blood vessels and establish

secondary sites of tumor growth throughout the body a process called metastasis a well-known risk factor for small cell lung cancer and some types of non small cell lung cancer is smoking

tobacco and it's dose dependent which means that smoking more cigarettes over a longer

period of time increases the risk another risk factor is exposure to radon a colorless odorless gas which is a natural breakdown product of uranium found in the soil other environmental

factors include asbestos air pollution and ionizing radiation like from medical imaging with

chest x-rays and CT scans there are also some G mutations that are known to be associated

with an increased risk of lung cancer development once it develops lung cancer tends to

metastasize quickly rapidly establishing sites of secondary tumors in other tissues tissues

particularly at risk as a secondary side are the mediastinum and hilar lymph nodes because of

their proximity to the lungs but other sites include the lung pleura which is the lining of the

lungs as well as the heart breasts liver adrenal glands brain and bones lung cancer can be

categorized as either small cell or non small cell carcinomas small cell carcinomas account for a small portion of lung cancers and originate from small immature neuro endocrine cells that

means that non small cell carcinomas account for most lung cancers and these can be further

subdivided into four categories adenocarcinomas which frequently form glandular structures or had the ability to generate mucin squamous cell carcinomas which have squamous or

square shaped cells that produce keratin carcinoid tumors from mature neuro endocrine cells

and large cell carcinomas which lack both glandular and squamous differentiation small cell

carcinoma is strongly associated with smoking and usually develops centrally in the lung neuro

main bronchus in general these grow the fastest and more rapidly metastasized to other organs

than other types of non-small cell lung cancers because by the time it's diagnosed it's common to find large tumors in multiple locations both within and outside the lung typically when

small cell carcinoma is within one lung it's considered limited if it spreads beyond one lung it's

considered extensive small cell carcinomas can also sometimes secrete hormones and that can

lead to what's called a paraneoplastic syndrome one example is when the tumor releases

adrenocorticotropic hormone causing an increase in production and release of cortisol from

the adrenal glands this causes what's known as Cushing's syndrome which causes a number of

other symptoms including an elevated blood glucose and high blood pressure another example

is when the tumour releases antidiuretic hormone which causes water retention leading to high

blood pressure edema and concentrated urine a slightly different type of paraneoplastic

syndrome is when the small cell carcinoma prompts the body to produce Auto antibodies

which bind and destroy neurons causing lambert-eaton myasthenic syndrome which is a type 2 hypersensitivity reaction non-small cell carcinomas are more of a mixed bag in terms of

where they usually arise just like small cell carcinomas squamous cell carcinoma tends to be

centrally located and has a strong association with smoking contrast adenocarcinoma tends to

develop peripherally in a bronchial or alveolar wall and doesn't have a link to smoking large

 cell carcinomas and bronchial carcinoid tumors can be found throughout the lungs centrally

and peripherally of these two large cell carcinoma is linked to smoking both adenocarcinoma

and squamous cell carcinoma can form Pancoast tumors which are masses in the upper region

 of the lung that compressed the blood vessels and nerves located there in particular Pancoast tumor can compress and damage the thoracic Inlet the brachial plexus and cervical

sympathetic nerves leading to their dysfunction in horner syndrome clinical symptoms of

Horner syndrome include a constricted pupil a drooping upper eyelid and loss of ability to sweat on the same side of the body as the dysfunctional sympathetic nerve a classic

paraneoplastic syndrome associated with squamous cell carcinoma is the release of parathyroid

 hormone which depletes calcium from the bones causing them become brittle and increases

calcium levels in the blood and finally a paraneoplastic syndrome specific to carcinoid tumors

 is carcinoid syndrome which causes the secretion of hormones particularly serotonin which

 leads to increased peristalsis in diarrhea as well as bronchoconstriction which causes asthma

since non-small cell carcinomas tend to be slower growing and slower to spread than small cell

 carcinomas staging is more elaborate it's called TNM staging and represents three diagnostic

categories t4 tumor size and extent of local extension and for spread into nearby lymph nodes

in the chests especially the mediastinum in hilar lymph nodes and m4 metastasis to the

secondary site within each of these categories are sub stages t0 through t4 and 0 through n 3 and m0 or m1 where an increasing number means increasing severity finally the combinations

of these sub stages determine the stage group assigned 0 to 4 so as an example if the diameter of the tumor is less than or equal to three centimeters and not in the main bronchus has

invaded the hilar lymph node on the same side of the chest but has not spread outside the

chest to other tissues it's categorized as T 1 N 1 M 0 and can be considered stage group - but if

the tumor metastasizes to a secondary site it's considered M 1 in stage in group 4 regardless of

 its T or n value symptoms of lung cancer vary depending on the size and location of the

tumor whether or not it's spread to other organs and whether or not it generates hormones all

of which is often predicted by the type of cancer in response to the cancer cells the body

mounts an immune response which results in the release of chemokines like tumor necrosis

factor-alpha interleukin-1 beta and interleukin 6 which can cause weight loss fevers and night

 sweats if the primary tumor physically obstructs the airway and presses on surrounding tissue

structures it can cause a cough shortness of breath and leads to a pneumonia and the lung tissue behind the obstruction compression of nearby nerves can cause pain and compression of

specific nerves like the recurrent laryngeal nerve and phrenic nerves can cause changes in

voice or difficulty breathing respectively compression of nearby vessels like the superior vena

 cava can cause a backup of blood in the face leading to facial swelling and shortness of breath finally if a cancer cell invades into a blood vessel then mucus can get blood-tinged or blood

clots can get coughed up initially lung cancer is usually identified as a coin shaped spot called a coin lesion on chest x-ray or a non calcified nodule on a chest CT scan infections can also

cause similar shaped spots so a tissue biopsy from a bronchoscopy you are a CT guided fine

needle aspiration is typically done to make a hysto pathologic diagnosis even though

treatment all vary by category and stage of the lung cancer common treatments are the use of

 surgery if appropriate chemotherapy or immunotherapy and radiation therapy when possible

in general the goal of surgery is to remove as much of the tumor ideally all of it and have a

small border of healthy tissue around it so that all of the cancerous cells are gone depending

on the size and location of the tumor a small wedge of tissue might be taken or up to an entire lung in which case the airway is sutured shut to prevent air from leaking into the body cavity

in addition it's common to remove nearby lymph nodes which the tumor might have

metastasized to as well as manage clinical symptoms since pain is a significant chronic

symptom of lung cancer it's often managed through both non pharmacological approaches

like yoga and guided imagery as well as pain medications all right as a quick recap lung cancer

is the uncontrolled growth of respiratory epithelial cells the minority are small cell cancers and the majority are non small cell cancers which are further categories into adenocarcinoma

squamous cell carcinoma bronchial carcinoid and large cell carcinoma some common issues for all lung cancers is that they can cause airway obstruction the compression of nearby nerves in

 the superior vena cava cause paraneoplastic syndromes and induce an immune response which

 causes symptoms like weight loss fevers and night sweats overall lung cancers have a high rate

of metastasis to other organs and are treated with a combination of surgery chemotherapy immunotherapy and radiation depending on the situation. Next Different type of lung cancer

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