🟣 Bladder Cancer
Urothelial (TCC), squamous cell, adenocarcinoma — risk factors, staging, NMIBC vs MIBC, TURBT, intravesical therapy, radical cystectomy — MRCS high-yield.
Pathology & Risk Factors
Epidemiology
Bladder cancer is the 4th most common cancer in men and the most common urothelial malignancy. The bladder is the most common site for urothelial carcinoma (90%), with the renal pelvis (8%), ureter (1%), and urethra (1%) accounting for the remainder. Peak incidence is in the 7th decade, with a male:female ratio of approximately 3:1.
| Feature | Detail |
|---|---|
| Incidence (UK) | ~10,000 new cases/year; 4th most common male cancer |
| Peak age | 65–75 years; rare under 40 |
| Sex ratio | Male:female ~3:1 — partly explained by higher smoking rates and occupational exposure historically |
| Mortality | ~5,000 deaths/year in the UK; most deaths from muscle-invasive or metastatic disease |
| Recurrence | NMIBC has high recurrence rate (~50–70% at 5 years) — lifelong cystoscopic surveillance required |
Histological Subtypes
The subtype of bladder cancer is closely linked to the cause and has major implications for treatment and prognosis.
Urothelial (TCC)
~90% of bladder cancers
- Transitional cell carcinoma — now termed urothelial carcinoma (UC)
- Arises from the urothelium lining the entire urinary tract
- Can be papillary (exophytic, lower grade, better prognosis) or flat (CIS — high-grade, aggressive)
- Multifocal — “field change” of entire urothelium due to carcinogen exposure
- Upper tract TCC (renal pelvis/ureter) in 2–4% of bladder TCC patients
- Risk factors: smoking, aromatic amines, cyclophosphamide, pelvic radiation
Squamous Cell Carcinoma
~5% in Western countries; ~80% in endemic areas
- Arises from squamous metaplasia of the urothelium
- In the West: chronic catheterisation, bladder stones, recurrent UTIs, radiation
- Schistosoma haematobium — endemic cause in sub-Saharan Africa and Middle East; ~80% of bladder cancer in Egypt is SCC
- Presents late — usually deeply invasive at diagnosis
- Less chemosensitive than TCC
- Keratinising squamous metaplasia on cystoscopy is a pre-malignant lesion
Adenocarcinoma
<2%
- Arises from urachal remnants (dome of bladder) or glandular metaplasia
- Urachal carcinoma — occurs at the dome; associated with signet-ring cell variant
- Also seen in bladder exstrophy
- Poor prognosis; often presents at advanced stage
- Treatment: radical cystectomy ± partial urachal resection for urachal variant
Small Cell / Neuroendocrine
<1% — rare but aggressive
- Highly aggressive — analogous to small cell lung carcinoma
- Paraneoplastic syndromes possible (SIADH, Cushing’s)
- Early haematogenous spread — often metastatic at presentation
- Cisplatin-based chemotherapy is the primary treatment
- Very poor prognosis
Risk Factors
🚬 Smoking
Most important modifiable risk factor — accounts for ~50% of all bladder cancers.
Tobacco combustion produces aromatic amines and nitrosamines → concentrated in urine → prolonged contact with urothelium → DNA damage.
Risk is 3–4× that of non-smokers; dose-dependent. Risk returns to near-normal ~10 years after cessation.
Tobacco combustion produces aromatic amines and nitrosamines → concentrated in urine → prolonged contact with urothelium → DNA damage.
Risk is 3–4× that of non-smokers; dose-dependent. Risk returns to near-normal ~10 years after cessation.
🏭 Occupational Carcinogens
Aromatic amines (2-naphthylamine, benzidine, 4-aminobiphenyl) — historically the most studied occupational carcinogens.
Industries at risk: rubber, leather, printing, textile dye, hairdressing (hair dyes), aluminium smelting, truck driving (diesel exhaust).
Latency period up to 25 years after exposure — occupational history is essential in all bladder cancer patients.
Industries at risk: rubber, leather, printing, textile dye, hairdressing (hair dyes), aluminium smelting, truck driving (diesel exhaust).
Latency period up to 25 years after exposure — occupational history is essential in all bladder cancer patients.
🪱 Schistosomiasis
Schistosoma haematobium — causes squamous cell carcinoma (not TCC).
Endemic in sub-Saharan Africa, Egypt, Middle East. Eggs deposited in bladder wall → chronic granulomatous inflammation → squamous metaplasia → SCC.
Classic: painless terminal haematuria + “sandy patches” on cystoscopy (calcified ova). AXR shows tram-line calcification of bladder wall.
Treatment: praziquantel. Leading cause of bladder cancer worldwide by case volume.
Endemic in sub-Saharan Africa, Egypt, Middle East. Eggs deposited in bladder wall → chronic granulomatous inflammation → squamous metaplasia → SCC.
Classic: painless terminal haematuria + “sandy patches” on cystoscopy (calcified ova). AXR shows tram-line calcification of bladder wall.
Treatment: praziquantel. Leading cause of bladder cancer worldwide by case volume.
💊 Cyclophosphamide
Alkylating chemotherapy agent metabolised to acrolein — excreted in urine → direct urothelial toxicity.
Causes haemorrhagic cystitis acutely and increases TCC risk long-term (~9× relative risk).
Prevention: Mesna (2-mercaptoethane sulfonate sodium) — binds acrolein in urine, neutralising it. Given with each cyclophosphamide dose.
Ifosfamide also metabolised to acrolein — same risk, same mesna prophylaxis.
Causes haemorrhagic cystitis acutely and increases TCC risk long-term (~9× relative risk).
Prevention: Mesna (2-mercaptoethane sulfonate sodium) — binds acrolein in urine, neutralising it. Given with each cyclophosphamide dose.
Ifosfamide also metabolised to acrolein — same risk, same mesna prophylaxis.
☢️ Pelvic Radiation
Prior radiotherapy for prostate, cervical, or rectal cancer increases bladder cancer risk 2–4×.
Causes radiation cystitis acutely and urothelial DNA damage long-term → increased TCC and SCC risk.
Latency: 10–20 years post-radiotherapy.
Also causes haemorrhagic radiation cystitis (treated with hyperbaric oxygen therapy in refractory cases).
Causes radiation cystitis acutely and urothelial DNA damage long-term → increased TCC and SCC risk.
Latency: 10–20 years post-radiotherapy.
Also causes haemorrhagic radiation cystitis (treated with hyperbaric oxygen therapy in refractory cases).
🔁 Chronic Irritation
Indwelling urethral catheter — chronic inflammation → squamous metaplasia → SCC. Risk increases dramatically with long-term catheterisation (>10 years).
Bladder calculi — chronic mechanical irritation → squamous metaplasia → SCC.
Recurrent UTIs — inflammation and bacterial metabolites → urothelial dysplasia.
Phenacetin / aristolochic acid — analgesic nephropathy → upper tract TCC risk.
Bladder calculi — chronic mechanical irritation → squamous metaplasia → SCC.
Recurrent UTIs — inflammation and bacterial metabolites → urothelial dysplasia.
Phenacetin / aristolochic acid — analgesic nephropathy → upper tract TCC risk.
Field Change Theory — Why Bladder TCC is Multifocal
The “Field Defect” / Field Change Effect
The entire urothelium — from renal pelvis to urethra — is exposed to the same carcinogens concentrated in urine for the same duration. This creates a “field defect”: the entire urothelial surface is at risk of malignant transformation, not just one point.
This explains several important clinical observations:
- Multifocality: ~30% of patients with bladder TCC have multiple synchronous tumours at first diagnosis
- Upper tract TCC: Patients with bladder TCC have a 2–4% lifetime risk of developing upper tract TCC (renal pelvis/ureter) — hence CT urogram at diagnosis and surveillance of upper tracts
- Urethral involvement: TCC can develop in the urethra (particularly the prostatic urethra) — a risk factor for urethral recurrence after radical cystectomy
- Lifelong surveillance: Even after TURBT and intravesical therapy, the entire urothelium remains at risk — explaining the high recurrence rates and the need for lifelong cystoscopic surveillance
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