Lung Cancer

Lung cancer

Definition: Uncontrolled invasive (malignant) growth originating from the lungs

Presentation: 

Depends on the site of the tumour and the type of cancer. 

Patients may present with

Chest signs and symptoms: (more common in cancers occurring centrally in the bronchial tree, late symptoms in peripheral cancers, may also present on a background of existing lung problems eg. COPD or emphysema) 

*Haemoptysis

*Cough

Wheeze

Stridor

Pain

Hoarse voice

clubbing

lymphadenopathy

localized chest signs

superior vena cava obstruction - caused by compression of the superior vena cava

.

Non specific symptoms

Weight loss

Anorexia

Lethargy

Anaemia

Incidentally with chest x ray

Visible mass

Hilar enlargement/visible nodes

pleural effusion

lobar collapse

through symptoms caused by metasteses

Bone: pain

Brain: Hemiparesis, fits

Liver: jaundice

Skin: nodules

Also if the primary tumour invades into surrounding tissues, it may causes symptoms. For example a tumour affecting the phrenic nerve would cause a raised hemidiaphragm, and invasion of the recurrent laryngeal nerves may cause vocal cord palsy and hoarseness, and diminished cough reflexes. A pancoast tumor refers to a lung tumor in the superior sulcus and causes ipsilateral horner's syndrome as it affects the stellate ganglion, pain due to erosion of the first and second ribs, and wasting of the small muscles of the hand due to brachial plexus invasion.

through paraneoplastic syndromes (symptoms caused by molecules produced by the cancer cells) or neuroendocrine syndromes in small cell carcinomas

Peripheral neuropathy

cerebellar degeneration

Lambert-eaton myasthenic syndrome

Dermatomyositis

Nephrotic syndrome

Thrombophlebitis migrans

Hypercalcaemia- could be caused by bone metastases or in small cell carcinomas, a parathyroid hormone related protein which is secreted by the cancer cells.

Syndrome of inappropriate ADH (most common paraneoplastic syndrome in small cell carcinoma)

Gynaecomastia

Cushing's syndrome

Causes/risk factors:

Smoking - The risk of lung cancer increases by 100% per cigarette smoked a day ie. someone who smokes 20 a day is 20 times more likely to suffer from lung cancer than someone who has never smoked. Once smoking is stopped, this risk roughly halves every 5 years.

Second hand smoke/passive smoking

Asbestos- linear relationship between asbestos exposure and risk of lung cancer. This risk is multiplied if the person smokes as well.

Genetics- family history of lung cancer.

Urban environment

Ionising radiation

Diffuse lung fibrosis

Lack of dietary fruit and vegetables- b-carotene found in fruit and vegetables lower lung cancer risk

Types of lung cancer 

Divided into small cell carcinomas (20%)

Non small cell carcinomas (80%) which is made up of squamous cell carcinomas (45%) adenocarcinomas (20%) and large cell (undifferentiated) carcinomas(15%)

Small cell carcinomas - arises from neuroendocrine cells, rapid growth and early metastasis gives it a poor prognosis.

Non small cell carcinomas - squamous cell carcinomas tend to cavitate, adenocarcinomas are more common in those who don't smoke, and large cell carcinomas are cancers which do not show differentiation between squamous or glandular cells.

 Investigations and management

Bloods : FBC, Liver function tests

Chest x ray (may show mass, or metastases in the bones)

Sputum cytology

bronchoscopy Percutaneous needle biopsy

Histology/cytology from metastatic site (eg. pleural effusion, lymph nodes) (to help define which type of cancer it is and for grading)

If bronchoscopy does not give a definitive diagnosis, needle biopsy under CT or fluoroscopic imaging may be performed. 

Bone marrow aspiration and trephine may show metastases (95% of small cell) Lung function tests are also performed to help determine operability. 

Grading and staging

Staging should include a chest-abdo CT scan, a radioisotope bone scan, liver ultrasound and a PET scan.

Staged with TNM system 

Treatment

Non small cell carcinoma

- Surgery if limited disease (T1N0M0, T2N0M0, and sometimes T2N1M0) and patient is fit enough to undergo surgery. 

- Neoadjuvant or adjuvant chemotherapy may be used. 

- Curative radiotherapy for patients who are not fit for surgery but not widely spread cancer. 6000cGy over 6 weeks. 

- If disease is advanced, palliative radiotherapy can be considered if the patient is symptomatic. Radiotherapy may cause tiredness, oesophagitis and skin changes as adverse events. 

- Chemotherapy usually is not effective on its own. It produces a minor survival benefit to patients who respond, but also has its toxicities. 

Small cell carcinoma 

95% present with metastatic disease

Primarily treated with chemotherapy - usually etoposide and cisplatin. 80% respond, and 60% go into complete remission. 

Prognosis

The prognosis of lung cancer depends on the type of cancer and how far it has spread and it's grading. 

Early non small cell cancers have a five year survival of around 5-40%. This number is higher in those with operable adenocarcinoma, where survival ranges between 38-79%. In those receiving radical radiotherapy, survival rate at 5 years is around 6%, 

Small cell cancer has a low survival rate, with a median survival rate of 3 months if the cancer is untreated. When treated, 10-20% will survive for 2 years and 5% for five or more years.