Definition Testicular cancer: A malignant tumour originating from the testicles (testes). Epidemiology Most common cancer in men aged 15-35 years in the UK. Higher incidence in Caucasian men. Undescended testes (cryptorchidism) increases risk. Pathophysiology Majority are germ cell tumours: either seminomas or non-seminomas. Other types: Leydig cell tumours, Sertoli cell tumours, and lymphomas (rare). Clinical Presentation Painless lump or swelling in one testicle. Dragging sensation or testicular discomfort. Advanced disease: Back pain, weight loss, and symptoms of metastasis. Gynaecomastia in cases with high hCG production. Investigations Scrotal ultrasound: First-line imaging. AFP, hCG, and LDH: Tumour markers. Chest X-ray, CT, and MRI: To check for metastasis. Testicular biopsy: Rarely done due to risk of spread; orchiectomy is diagnostic and therapeutic. Management Orchiectomy: Surgical removal of the affected testicle. Surveillance post-surgery for early-stage disease. Chemotherapy, especially for non-seminomas. Radiation therapy primarily for seminomas. Retroperitoneal lymph node dissection in some cases. Prognosis Highly treatable, especially when detected early. 5-year survival rate exceeds 95% for localised disease. Complications Metastasis, commonly to lungs, liver, and brain. Infertility due to treatment or bilateral disease.