P03.002 Bladder cancer

Bladder cancer is a common malignancy of the urinary tract, primarily affecting the epithelial lining of the bladder. This guide provides a detailed overview of bladder cancer, suitable for students preparing for the PLAB exam.

Introduction

Bladder cancer typically arises from the urothelium, the epithelial lining of the bladder. The majority of bladder cancers are urothelial (transitional cell) carcinomas, but other types include squamous cell carcinoma and adenocarcinoma.

Epidemiology

• Incidence: Bladder cancer is the 10th most common cancer worldwide.
• Gender: More common in men than women, with a ratio of approximately 3:1.
• Age: Most cases occur in individuals over 65 years of age.

Risk Factors

• Smoking: The most significant risk factor, contributing to about half of all cases.
• Occupational exposure: Chemicals such as aromatic amines used in dye and rubber industries.
• Chronic bladder irritation: Recurrent urinary infections, long-term catheter use, and bladder stones.
• Medications: Certain chemotherapy drugs (e.g., cyclophosphamide) and diabetes medication pioglitazone.
• Radiation exposure: Previous pelvic radiation therapy.
• Family history: Genetic predisposition may play a role.

Pathophysiology

Bladder cancer originates in the urothelial cells lining the bladder. Genetic mutations and environmental factors contribute to the malignant transformation of these cells.

Clinical Presentation

• Hematuria: The most common symptom, usually painless and gross (visible) or microscopic.
• Irritative voiding symptoms: Dysuria, frequency, and urgency may occur, especially in advanced cases.
• Pelvic pain: Typically seen in advanced disease with local invasion.
• Systemic symptoms: Weight loss, fatigue, and other symptoms of metastatic disease in late stages.

Diagnosis

History and Physical Examination

• Detailed medical history focusing on risk factors, smoking history, and occupational exposures.
• Physical examination including abdominal and pelvic examination.

Investigations

1. Urine cytology: Detection of malignant cells in urine; useful but not definitive.
2. Cystoscopy: Direct visualization of the bladder lining; allows for biopsy of suspicious areas.
3. Imaging:
   • Ultrasound: Initial screening tool.
   • CT Urography: Provides detailed imaging of the urinary tract.
   • MRI: Useful in assessing the extent of local invasion.
4. Biopsy: Histopathological examination of biopsy samples obtained during cystoscopy confirms diagnosis and provides information on tumor grade and stage.

Staging

Bladder cancer staging is based on the TNM system:

• T (Tumor): Depth of invasion into the bladder wall.
• N (Nodes): Presence of regional lymph node involvement.
• M (Metastasis): Presence of distant metastasis.

Table 1: TNM Staging for Bladder Cancer

Treatment

Non-Muscle Invasive Bladder Cancer (NMIBC)

• Transurethral Resection of Bladder Tumor (TURBT): Mainstay of treatment for diagnosis and initial management.
• Intravesical therapy: Bacillus Calmette-Guerin (BCG) or mitomycin C to reduce recurrence risk.

Muscle Invasive Bladder Cancer (MIBC)

• Radical cystectomy: Removal of the bladder, often with urinary diversion (e.g., ileal conduit).
• Neoadjuvant chemotherapy: Given before surgery to shrink the tumor and improve outcomes.
• Radiation therapy: An option for those who are not surgical candidates.

Metastatic Bladder Cancer

• Chemotherapy: Systemic treatment with agents such as cisplatin and gemcitabine.
• Immunotherapy: Checkpoint inhibitors like pembrolizumab for advanced or metastatic disease.

Prognosis

The prognosis depends on the stage and grade of the tumor at diagnosis. Early-stage bladder cancer has a good prognosis with appropriate treatment, while advanced disease has a poorer outlook.

Points to Remember

• Smoking is the most significant risk factor for bladder cancer.
• Painless hematuria is the most common presenting symptom.
• Cystoscopy with biopsy is essential for diagnosis.
• Intravesical BCG is effective in preventing the recurrence of NMIBC.
• Radical cystectomy is the treatment of choice for MIBC.
• A multidisciplinary approach is crucial for managing advanced bladder cancer.

Bibliography

1. Campbell-Walsh-Wein Urology. (2016). Elsevier.
2. National Cancer Institute. Bladder Cancer Treatment (PDQ®)–Health Professional Version.
3. American Cancer Society. (2021). Bladder Cancer.
4. European Association of Urology. (2021). EAU Guidelines on Muscle-invasive and Metastatic Bladder Cancer.
5. Kamat, A.M., et al. (2016). Bladder cancer. The Lancet.