Lung cancer – causes, symptoms, diagnosis, treatment, pathology
09
October

By Adem Lewis / in , , , , , , , , , , /


Learning medicine is hard work! Osmosis makes it easy. It takes your lectures and notes to create
a personalized study plan with exclusive videos, practice questions and flashcards, and so
much more. Try it free today! 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 in other tissues. The major cause of lung cancer is smoking
tobacco products, and it has contributed to the deaths of millions of people including
famous individuals like Walt Disney and Claude Monet. 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 root of the lung. The bronchi then divides into lobar bronchi,
which divide into segmental bronchi, then into subsegmental bronchi, which further branch
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 occurs. Lining these airways are several types of
epithelial cells which serve multiple functions. These include ciliated cells that have hair-like
project called cilia that work 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 bronchiolar epithelium, and neuroendocrine 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 detach from their basement membrane at the primary tumor site, 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 gene 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
site are the mediastinum and hilar lymph nodes because of their proximity to the lungs, but
other sites include the lung pleura – the lining of the lungs, 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 neuroendocrine 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 have the ability to generate
mucin; squamous cell carcinomas; which have squamous, or square shaped, cells that produce
keratin; carcinoid tumors from mature neuroendocrine 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, near a main bronchus. In general, they grow the fastest and more
rapidly metastasize to other organs than other types of non-small cell lung cancers. Because of this, 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 is 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 symptoms including an elevated blood glucose and high
blood pressure. Another example is when the tumor 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 small cell carcinoma prompts the body to produce autoantibodies which bind
and destroy neurons causing myasthenic syndrome, which is a type II hypersensitivity reaction. Non-small cell carcinomas are more of a mixed
bag in terms of where they usually arise. Just like small cell carcinoma, squamous cell
carcinoma tends to be centrally located and has a strong association with smoking.,Smoking
also increases the risk of adenocarcinomas but they tend to develop peripherally, in
a bronchiole or alveolar wall, Large cell carcinomas and bronchial carcinoid tumors
can be found throughout the lungs – centrally and peripherally. Of these two, large cell carcinoma has a stronger
link l to smoking. Both adenocarcinoma and squamous cell carcinoma
can form Pancoast tumors, which are masses in the upper region of the lung that compress
the blood vessels and nerves located there. In particular, pancoast tumors can compress
and damage the thoracic inlet, brachial plexus, and cervical sympathetic nerves leading to
their dysfunction and 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 to become brittle and increasing 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 and diarrhea, and bronchoconstriction causing
asthma. While non-small cell carcinomas tend to grow
more slowly and be slower to spread than small cell carcinomas, the staging system is the
same for both. It’s called “TNM” staging and represents
three diagnostic categories: T, for tumor size and extent of local extension; N, for
spread into nearby lymph nodes in the chest, particularly the mediastinum and hilar lymph
nodes; and M, for metastasis to a secondary site. Within each of these categories are sub-stages,
T0-T4, N0-N3, and M0-M1, where an increasing number means increasing severity. Finally, the combinations of these sub-stages
determine thes stage group, assigned 0 to IV. So for example, if the diameter of the tumor
is less than or equal to 3 cm and not in a 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 T1, N1, M0 and can be considered stage group II. But if the tumor metastasizes to a secondary
site, it’s considered M1 and staging group IV regardless of it’s T or N value. Symptoms of lung cancer vary based on the
size and location of the tumor, whether or not is has 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 TNF-alpha,
IL1-beta, and IL-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 in 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 cells invade 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 chest CT. Infections can also cause similar shaped spots,
so a tissue biopsy from a bronchoscopy or a CT-guided fine-needle aspiration is typically
done to make a histopathologic diagnosis. Though treatment will vary by category and
stage of the lung cancer, often a commonality is 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 a tumor, ideally all of it, and to 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 may 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 typical to remove nearby
lymph nodes which have metastasis and manage clinical symptoms. Since pain is a significant chronic symptom
of lung cancer, it’s often managed through both nonpharmacologic approaches like yoga
and guided imagery as well as pain medications. So, a quick recap: Lung cancer is the uncontrolled
growth of respiratory epithelial cells. The minority are small cell cancers and th
cancers is that they can cause airway obstruction, compression of nearby nerves and 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.


24 thoughts on “Lung cancer – causes, symptoms, diagnosis, treatment, pathology

  1. Its always pleasure to watch the videos..the process through which u make it is really awesome….short time..grasping way ..learning lots …

  2. I was diagnosed with stage 4 lung cancer in 2011, and that year we were excited to be celebrating my six year survivor-ship anniversary – a survival that was not remotely contemplated in 2016. Since i diagnosis i have learnt a lot about lung cancer, the first few years were confronting. I had no clue that my LUNG (left) was responsible for these combined symptoms! Fatigue, chest, neck and shoulder pain. My life changed in just one breath when my Doctor diagnosed me with advanced lung cancer that was INOPERABLE, INCURABLE and TERMINAL. I will always remember the pain and tears from my husband’s face as well as my daughters and my close friends. Like many other people this was not the first time that my life was impacted by CANCER. In 2002 my sister was diagnosed with leukemia. Fortunately for us she was diagnosed at an late stage and she pass away. So when my doctor gave the news about me, We all put in mind positive energy to fight against it, Because I was not going to let that put an end to my smile. now i lives a normal healthy and active lifestyle thanks to the “Dr Adebola Herbal Herbs” which my husband doctors prescribed him. SO many good people have lost there life because of greed, The government will preach against herbal herbs because it only one true cure, But will make profit with pills because the money you treat the more money you spent, Thanks to my husband Doctor who told us this. I will want to advice anyone out here going through sorrow with Cancer to reach out to Dr Adebola and I guarantee you that you will be cured. Contact him via: ([email protected])? WhatsApp number (+19292018600).

  3. My father smoke from when He was 15 now he is almost 50.
    He started to loss weight and to sweat at night some year ago… Now he is so skinny and has voice problems and I tried to convince him to go get checked but he just insult me…

  4. HI 🙂 i spotted a little mistake: there is no edema for SIADH as paraneoplastic syndrome, because there is not enough fluid/water for retention. This is a possibilty to differentiale to increased scretion of ADH due to cirrhosis of the liver or congestive heart failure, where there is edema.

  5. Excellent presentation and very well explained video! Thank you so much for helping me to understand better! Lots of love ❤️ 2/8/2019

  6. Thanks a lot for a great information and explanation .. 👍my mom is diagnose lung cancer , this info help me to understand much better .

  7. Hi Everybody!! What is the stage were a person does not Qualified for a treatment? Thank you for this video is awesome!!.

  8. hey guys…could please somebody tell me if I can get a lung cancer I'm 15 years old and I have almosf all the simptoms for lung cancer(oh and I have asthma)pleade can somebody tell me if I have lung cancer at the age of 15🥺🙏

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