Lung Cancer Histology

• Lung cancer is the third most prevalent cancer in the UK, following breast and prostate cancer.
• Smoking stands out as the primary causative factor, with approximately 80% of lung cancer cases considered preventable.

Histology of Lung Cancer

• Lung cancer is histologically divided into Small-cell lung cancer (SCLC) and Non-small-cell lung cancer (NSCLC).
• SCLC accounts for about 20% of cases.
• NSCLC makes up around 80% of cases.

Non-Small-Cell Lung Cancer (NSCLC) Subtypes

• Adenocarcinoma represents about 40% of total lung cancers.
• Squamous cell carcinoma constitutes approximately 20% of total lung cancers.
• Large-cell carcinoma makes up about 10% of total lung cancers.
• Other types account for the remaining 10% of total lung cancers.

Small-Cell Lung Cancer (SCLC)

• SCLC cells feature neurosecretory granules that release neuroendocrine hormones.
• SCLC may induce paraneoplastic syndromes.

Mesothelioma

• It is a lung malignancy affecting the mesothelial cells of the pleura.
• It is closely associated with asbestos inhalation, displaying a latency period of up to 45 years between exposure and development.
• Mesothelioma carries a grim prognosis, with chemotherapy offering palliative benefits.

Presentation of Lung Cancer

• Common symptoms include shortness of breath, cough, and coughing up blood (haemoptysis).
• Additional signs encompass finger clubbing and recurrent pneumonia.
• Patients may experience weight loss and lymphadenopathy, often with supraclavicular nodes as the initial finding upon examination.

Extrapulmonary Manifestations and Paraneoplastic Syndromes

• These are associated with various lung cancer types and distributions.
• Recurrent laryngeal nerve palsy leads to a hoarse voice because of tumor compression in the mediastinum.
• Phrenic nerve palsy, resulting from nerve compression, leads to diaphragm weakness and breathlessness.
• Superior vena cava (SVC) obstruction, triggered by direct tumor compression, manifests as facial swelling, breathing difficulties, and distended veins in the neck and upper chest.

Pemberton’s Sign

• Raising the hands above the head induces facial congestion and cyanosis, indicative of SVC obstruction.
• SVC obstruction constitutes a medical emergency.

Horner’s Syndrome

• It is characterized by partial ptosis, anhidrosis, and miosis.
• Pancoast tumors in the pulmonary apex can cause Horner's Syndrome by pressing on the sympathetic ganglion.

Syndrome of Inappropriate ADH (SIADH)

• It is caused by ectopic ADH secretion from small-cell lung cancer, leading to hyponatraemia.
• Cushing’s syndrome is triggered by ectopic ACTH secretion from small-cell lung cancer.
• Hypercalcaemia is caused by ectopic parathyroid hormone secreted by squamous cell carcinoma.

Limbic Encephalitis

• It is a paraneoplastic syndrome in which small-cell lung cancer prompts the immune system to target brain tissues, particularly the limbic system.
• This inflammation leads to symptoms like memory impairment, hallucinations, confusion, and seizures, and it is linked to anti-Hu antibodies.

Lambert-Eaton Myasthenic Syndrome

• Antibodies against small-cell lung cancer cells impair voltage-gated calcium channels in motor neurones.
• This results in proximal muscle weakness and can affect intraocular muscles, causing double vision (diplopia); eyelid muscles, causing drooping (ptosis); and pharyngeal muscles, causing slurred speech and difficulty swallowing (dysphagia).
• Autonomic dysfunction may lead to dry mouth, blurred vision, impotence, and dizziness.

Referral Criteria

• NICE guidelines (Dec 2021) suggest a chest X-ray, within 2 weeks, for patients over 40 with clubbing, lymphadenopathy (supraclavicular or persistent cervical), recurrent chest infections, raised platelet count, or chest signs of lung cancer.
• Chest X-rays are also recommended for those over 40 with unexplained symptoms, especially smokers or those exposed to asbestos.
• Unexplained symptoms include cough, breathlessness, chest pain, fatigue, weight loss, or loss of appetite.

Investigations for Lung Cancer

• Chest X-ray is the initial test for suspected lung cancer with findings such as hilar enlargement, peripheral opacity, pleural effusion, or lung collapse.
• Contrast-enhanced CT scans of the chest, abdomen, and pelvis help stage the cancer, assess lymph node involvement, and detect metastases.
• PET-CT scans use radioactive tracers to identify metabolically active tissues, aiding in metastasis detection.
• Bronchoscopy with endobronchial ultrasound (EBUS) allows detailed tumor assessment and ultrasound-guided biopsies.
• Histological diagnosis requires a biopsy (bronchoscopy or percutaneous) to determine the cell type.

Treatment Options

• Treatment plans are determined at MDT meetings with pathologists, surgeons, oncologists, and radiologists.
• Surgery is the primary option for non-small-cell lung cancer confined to a single area, aiming for complete removal and cure.
• Radiotherapy can also cure early-stage non-small-cell lung cancer.
• Chemotherapy may be given alongside surgery or radiotherapy for better outcomes (adjuvant) or as palliative care in advanced cases.
• Small-cell lung cancer treatment typically involves chemotherapy and radiotherapy with a generally poorer prognosis than non-small-cell lung cancer.
• Endobronchial treatments with stents or debulking alleviate bronchial obstruction caused by lung cancer.

Lung Cancer Surgery Options

• Segmentectomy or wedge resection involves removing a segment or wedge of lung tissue.
• Lobectomy removes an entire lung lobe.
• Pneumonectomy involves removing an entire lung.

Types of Surgical Approaches

• Thoracotomy is open surgery involving an incision and rib separation.
• Video-assisted thoracoscopic surgery (VATS) is minimally invasive "keyhole" surgery.
• Robotic surgery.
• Minimally invasive methods like VATS or robotic surgery are favored for quicker recovery and lower complication rates.
• Anterolateral, axillary, and posterolateral (most common) thoracotomy incisions exist.
• A thoracotomy scar indicates either a lobectomy, pneumonectomy, or lung volume reduction surgery for COPD.
• A right-sided mini-thoracotomy may indicate minimally invasive mitral valve surgery.
• Absent breath sounds on an entire side may indicate a pneumonectomy.
• Focal absent breath sounds may suggest a lobectomy.
• Lobectomies and pneumonectomies are used to treat lung cancer but were previously used to treat tuberculosis.