how do diagnose cancer

Diagnosis of cancer involves a systematic approach starting with a comprehensive clinical assessment including history and physical examination tailored to the suspected cancer type. Initial investigations often include blood tests, imaging, and tissue sampling.

For suspected lung cancer, a contrast-enhanced chest CT scan including liver, adrenals, and lower neck is recommended to confirm diagnosis and stage the disease. Sputum cytology is reserved for patients with centrally placed nodules who cannot tolerate bronchoscopy or invasive tests ¹.

In cases of metastatic malignant disease of unknown primary origin (MUO), initial diagnostic tests include full blood count, biochemistry, chest X-ray, CT scans of chest, abdomen, and pelvis, symptom-directed endoscopy, and biopsy with histological examination including immunohistochemistry to distinguish carcinoma from other malignancies ². Tumour markers are generally not measured during diagnosis except in specific scenarios such as germ-cell tumours or hepatocellular cancer ².

For suspected cancers identified in primary care, referral via a suspected cancer pathway is advised based on clinical findings such as abnormal imaging (e.g., chest X-ray suggesting lung cancer), physical examination (e.g., malignant-feeling prostate on digital rectal exam), or positive faecal occult blood tests for colorectal cancer ³.

In ovarian cancer suspicion, serum CA125 measurement is recommended in women with relevant symptoms, followed by ultrasound if CA125 is elevated. Referral for further investigation is made if ultrasound suggests ovarian cancer ⁴.

Throughout the diagnostic process, clear communication with the patient is essential, providing understandable information about tests, treatments, and prognosis, and supporting informed decision-making ¹.