B25. Surgical management of lung cancer

Lung cancer is the second most frequent cancer, but it causes the most cancer-related deaths worldwide. Smoking is famously the biggest risk factor, and also the reason that lung cancer incidence increased dramatically during the 1900s. 85 – 90% of cases of lung cancer are attributable to smoking.

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

• Non-small-cell lung cancer (NSCLC)
  • Adenocarcinoma
  • Squamous cell carcinoma (SCC)
  • Large cell lung carcinoma (LCLC)
• Small cell lung cancer (SCLC)

Non-small cell lung cancer (NSCLC) accounts for 85% of cases, while SCLC accounts for 15% of cases. Of the NSCLC, adenocarcinoma is the most common, followed by SCC and LCLC. SCLC is a neuroendocrine tumour.

Etiology

• Smoking
• Environmental exposure to carcinogens
  • Radon gas
  • Uranium
  • Asbestos
  • Polycyclic hydrocarbons
• Family history (Genetic susceptibility)

Pathology

Lung cancer usually spreads to:

• Hilar lymph nodes
• Mediastinum
• Pleura (pleural carcinosis)
• Brain
• Adrenal gland

Pancoast tumour

Any lung tumor, regardless of subtype, is called a Pancoast tumor if it occurs in the apex of the lung. There are many structures in that area which the tumor can compress or invade, and so Pancoast tumors therefore have multiple extra consequences:

• Shoulder pain – due to compression of local nerve roots
• Pain in upper extremities – due to compression of the brachial plexus
• Horner syndrome – due to compression of the stellate ganglion
  • Horner syndrome is a triad of miosis, ptosis, and facial anhidrosis
• Superior vena cava syndrome – due to compression of the SVC
  • Dyspnoea
  • Oedema of the face
• Hoarse voice – due to compression of the recurrent laryngeal nerve

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 most common symptom is cough, which is present in 50 – 75% of lung cancer cases at presentation. The second most common symptom is dyspnoea.

Other possible clinical features include:

• Chest pain
• Haemoptysis
• Hoarseness
• Weight loss
• Stridor (due to tracheal obstruction)
• Dysphagia (due to oesophageal obstruction)
• Bone pain (due to metastases)
• Cushing syndrome (due to paraneoplastic syndrome)
• Neurological symptoms (due to metastases)
• SIADH (due to paraneoplastic syndrome)
• Superior vena cava syndrome
• Horner syndrome
• Clubbing of the fingers (due to paraneoplastic syndrome)

Diagnosis and evaluation

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.

For a definite diagnosis, histopathology is required. Ideally, a large enough biopsy should be taken to allow for immunohistochemical and genetic analysis, as this has implications for treatment and prognosis. There exist multiple modalities for obtaining biopsy, including endobronchial ultrasound-guided biopsy (EBUS), transthoracic needle biopsy, transoesophageal endoscopic ultrasound, mediastinoscopy, etc.

Treatment

The treatment for NSCLC and SCLC is different. Surgery is the main treatment of NSCLC stages I – IIIa. It is not used for SCLC.

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.

Surgery is preferably performed with video-assisted thoracoscopy (VATS) rather than open surgery.