Endoscopy — Internal Diagnostic Imaging Procedure

Endoscopy encompasses a broad category of diagnostic and interventional procedures utilising an instrument called an endoscope. This long, flexible or rigid tube transmits high-definition digital images of internal mucosa to an external monitor. It also features specialised working channels through which clinicians can introduce micro-surgical tools to wash surfaces, aspirate fluids, excise polyps, or retrieve tissue specimens.

Depending on the anatomical site being investigated, the procedure carries specialised names. An upper gastrointestinal endoscopy (gastroscopy) examines the oesophagus, stomach, and duodenum, while a colonoscopy inspects the large bowel and rectum. Other variations include bronchoscopy for the airways and cystoscopy for the bladder. Beyond visual assessment, modern endoscopes often incorporate advanced imaging modalities, such as narrow-band imaging or endoscopic ultrasound (EUS), allowing specialists to measure the depth of tumour invasion into organ walls and adjacent lymph nodes.

Endoscopy plays an indispensable role throughout the cancer care pathway, from routine screening to precise cancer staging and symptom relief. In screening programmes, procedures like colonoscopy can find and remove pre-cancerous polyps before they ever develop into invasive tumours. For existing cancers, endoscopy provides the essential tissue samples needed for histopathology and biomarker testing, establishing the precise diagnosis. Furthermore, therapeutic endoscopy can relieve debilitating complications without major surgery, such as placing stents to open obstructed airways, bile ducts, or digestive passages.

Endoscopy is both an imaging tool and the primary vehicle for acquiring samples for downstream biomarker testing. Tissue specimens collected during endoscopy undergo histopathological examination under a microscope. Pathologists run immunohistochemical and molecular tests on these biopsies to identify key biomarkers, such as HER2, PD-L1, mismatch repair (MMR) proteins, or genetic mutations. Additionally, endoscopic ultrasound (EUS) uses high-frequency sound waves from the tip of the scope to evaluate tumour depth (T-stage) and guide fine-needle aspiration of suspicious regional lymph nodes.

Endoscopy is vital for detecting and managing cancers of the digestive tract, including oesophageal, gastric, colorectal, and duodenal malignancies. It is equally important in pulmonary oncology via bronchoscopy for diagnosing lung cancers and airway tumours. In addition, endoscopic techniques are routine in urological oncology (bladder and urethral tumours via cystoscopy), gynaecology (hysteroscopy), and head and neck oncology (laryngoscopy or nasopharyngoscopy to inspect the vocal cords, throat, and nasal passages).

The direct visualisation and histological confirmation provided by endoscopy determine whether a tumour is resectable and guide the selection of systemic therapy or radiotherapy. Very early, superficial cancers of the stomach, oesophagus, or bowel can sometimes be completely cured during the procedure itself using endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD). In palliative care, endoscopists deploy expandable metal stents through strictures caused by advanced tumours, restoring the patient's ability to swallow, digest food, or breathe comfortably.