Small cell lung cancer (SCLC) Flashcards
What is SCLC?
This is a malignant epithelial tumour arising from cells lining the lower respiratory tract.
The tumour cells are small and densely packed, with scant cytoplasm, finely granular chromatin and absence of nucleoli.
Aetiology of SCLC
Cigarette smoking is the most common cause
Pathophysiology of SCLC
SCLC comprises approximately 15% of lung cancers.
These tumours tend to arise in the central lung with mediastinal involvement.
It is an aggressive malignancy
Signs and symptoms of SCLC
Cough Dyspnoea Haemoptysis Chest and/or shoulder pain Weight loss Fatigue Wheeze Crackles Decreased breath sounds Dullness to percussion
Risk factors of SCLC
Cigarette smoking Environmental tobacco exposure FHx COPD Radon gas exposure Older age
Investigations of SCLC
CXR (can detect pulmonary nodules ), mass, lung collapse, pleural effusion.
Contrast-enhanced CT scan- shows the size, location and extent of the primary tumour
Sputum cytology- malignant cells in sputum
Bronchoscopy- endobronchial lesions
Biopsy- specimen for pathological diagnosis
Differentials of SCLC
NSCLC Pneumonia Carcinoid tumour Sarcoidosis Hamartoma Rheumatoid arthritis Pulmonary TB Germ cell tumour
Staging of SCLC
TNM staging
‘T’ in TNM for SCLC
Primary tumour (T stage):
TX: primary tumour cannot be assessed, or tumour proven by the presence of malignant cells in sputum or bronchial washings but not seen on imaging or bronchoscopy
T0: No evidence of primary tumour
Tis: carcinoma in situ
T1: ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus)
T2: >3 cm but ≤5 cm or tumour with any of the following features (T2 tumours with these features are classified as T2a if ≤4 cm or if size cannot be determined, and as T2b if >4 cm but ≤5 cm): involves main bronchus regardless of distance to the carina, but without involving the carina; invades visceral pleura; associated with atelectasis or obstructive pneumonitis that extends to the hilar region, either involving part of the lung or the entire lung
T3: >5 cm but ≤7 cm or directly invading any of the following: parietal pleura (PL3), chest wall (including superior sulcus tumours), phrenic nerve, parietal pericardium; or associated separate tumour nodule(s) in the same lobe as the primary
T4: tumours >7 cm or invading any of the following: the diaphragm, mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, oesophagus, vertebral body, or carina; separate tumour nodule(s) in a different ipsilateral lobe to that of the primary.
‘N’ in TNM for SCLC
Regional lymph nodes (N stage):
NX: Regional lymph nodes cannot be assessed
N0: no regional lymph node metastases
N1: metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension
N2: metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s)
N3: metastasis in contralateral mediastinal lymph node(s), contralateral hilar lymph node(s), ipsilateral or contralateral scalene lymph node(s), or supraclavicular lymph node(s).
‘M’ in TNM for SCLC
Distant metastasis (M stage):
M0: no distant metastasis
M1: distant metastasis
M1a: separate tumour nodule(s) in a contralateral lobe; tumour with pleural nodules; or malignant pleural or pericardial effusion that is due to cancer. Where tests and clinical judgment conclude that the effusion is not related to the tumour, then the effusion should not be used as a staging descriptor.
M1b: Single extrathoracic metastasis in a single organ and involvement of a single distant (nonregional) node
M1c: Multiple extrathoracic metastases in one or several organs.
