Lung cancer: Difference between revisions

Around 95% of all primary lung tumors are carcinomas (epithelial origin), and these four types are most important:

** [[Polycyclic hydrocarbon|Polycyclic hydrocarbons]]

* Family history (Genetic susceptibility)

Smoking is by far the important cause of lung cancer, and it's estimated that 90% of lung cancer cases would be avoided if not for smoking and 80% of lung cancer deaths are due to tobacco use. Lung adenocarcinoma is not as strongly associated with smoking and is actually more common in nonsmokers than in smokers. The other types of lung cancer are very strongly associated with smoking.

We can compare smoking habits with a measure called “pack-year”. If you have smoked 1 pack of cigarettes (20 pcs) every day for one year you have accumulated 1 pack-year. If you smoke one half pack every day for four years you have accumulated 2 pack-years. This allows us to quantify smoking habits, and it has prognostic significance. Higher pack years means higher risk of smoking-induced cancer, as well as a poorer prognosis in the case of lung cancer.

== Pathology ==

=== Localisation ===

The different types of lung tumors have a tendency to where they prefer to originate in the lung, either centrally or peripherally.

=== Metastasis ===

* Hilar lymph nodes

** Oedema of the face

* Hoarse voice – due to compression of the recurrent laryngeal nerve

=== Paraneoplastic syndrome ===

[[Paraneoplastic syndrome|Paraneoplastic syndromes]] are more frequent in lung cancer compared to other cancers, espacially in SCLC. Common occurrences include:

[[Lymphangitis carcinomatosa]] may occur in the lung. It’s caused by the lymph vessels being filled up with invading malignant tumor cells. This causes the lymph vessels to dilate and become visible.

== Clinical features ==

Lung cancer can produce many different signs and symptoms. They may be due to the intrathoracic effects, distant metastases, or paraneoplastic syndromes. Central carcinomas, like SCC and SCLC, tend to produce symptoms more often.

The initial investigation is usually [[chest x-ray]], which may show a solitary nodule. In this case, the patient proceeds to a contrast chest [[CT]].

Acquiring tissue specimens is better than acquiring cytologic specimens, as only tissue specimens yield enough material for immunohistochemistry and genetic testing. This is important for prognosis and treatment. However, cytologic specimen is usually sufficient to determine the histological subtype and to confirm the cancer diagnosis. Cytology is most commonly acquired from a malignant pleural effusion, but can also be acquired from sputum analysis and [[bronchoalveolar lavage]].

* Abdominal [[ultrasound]]

* If CT finds metastases (advanced disease), then perform brain MRI for brain metastases and x-ray/bone scintigraphy for skeletal metastases

== Treatment ==

The treatment for NSCLC and SCLC is different.

=== Non-small cell lung cancer (NSCLC) ===

For NSCLC, tumours up to and including stage IIIb are potentially curable:

=== Surgical treatment ===

Surgical options include wedge resection, segmentectomy, lobectomy, and pneumonectomy. The less invasive options are preferred if they allow for margin negative (R0) resection. Lobectomy is usually preferred over wedge resection or segmentectomy, as the risk for R1 resection is smaller, but the latter may be chosen if the patient is deemed to have insufficient pulmonary function to tolerate a lobectomy.

[[Category:Oncology]]

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