Flashcards in Urology - Bladder cancer Deck (38)
What is the most common bladder cancer?
Over 90% of bladder tumours are urothelial carcinoma (previously called TCCs). Non muscle invasive tumours are the most common.
NB - the term carcinoma is used in an imprecise way when applied to bladder cancers. Many bladder tumours that are called carcinomas show no evidence of basement membrane invasion and should perhaps be called papillomas. But historically they have been called carcinomas.
What are the macroscopic differences between high and low grade tumours?
Tumours can either be high grade or low grade. Low grade tumours are often easy to identify and often papillary. High grade tumours are often flat and difficult to visualise.
What is the most important factor when determining treatment for bladder cancer?
Muscle invasion is important. If this occurs, transurethral resection (TURBT) is insufficient and a radical cystoprostatectomy is advised.
Where is bladder cancer more common?
The incidence of bladder cancer varies significantly worldwide. Egypt, Western Europe, and North America have the highest rates. Asian countries have the lowest rates.
In what group of patients is bladder cancer more common?
Bladder cancer is more common in men cf. women (3:1) Although the disease can occur in young people, >90% of new cases occur in the >55 group.
Which groups of patients experience a higher mortality from bladder cancer?
Women, the elderly and black people all experience higher mortality from bladder cancer. There are many factors that may explain this increase.
Name some important predisposing/ risk factors for bladder cancer?
1) Chemical substances - e.g. aromatic amines used in rubber and dye industries, arsenic exposure in drinking water, high risk occupations such as painters, hairdressers and medical personnel (due to chemical exposure), pelvic radiation, chemotherapeutic agents (cyclophosphamide)
2) Smoking - most important causative factor
3) Type 2 diabetes - pyoglitazone may increase risk of bladder cancer in T2DM patients
4) Chronic inflammation
6) Indwelling catheters
8) Bladder diverticula
9) Ectopic vesicae
What sites are most common for bladder tumours?
Most tumours are at the base on the trigone and around the ureteric orficies.
What is the pathophysiology of bladder cancer?
Carcinogens are concentrated and excreted in the urine, thereby exposing the cells lining the urinary tract. This exposure is concentrated however in the bladder (where 95% of urothelial carcinomas arise) but malignant transormation can occur anywhere along the urinary tract.
What is the "field effect"?
About 70% of tumours in newly diagnosed patients are multiple, and in >50% of patients there is accompanying areas of dysplasia up to carcinoma in situ, either next to or in remote areas away from the primary tumour. These findings have led to the concept of the "field effect" in which exposure of the urothelium to carcinogens at roughly the same concentration gives rise to an epithelium, from which occassional cells become initiated and give rise to independent clones of transformed cells.
Are there any problems with the "field effect" theory of bladder cancer?
X chromosome inactivation studies suggest a single cell origin for most tumours, rather than the multifocal nature of cancer explained by the field effect. But both concepts are clinically useful: a point mutation may initiate the process, confering a growth advantage to cells that later develop the malignant phenotype.
What genes play a role in the development of bladder cancer? Are any genes associated with a better or worse prognosis?
Genes involved in chemical detoxification such as glutathione S transferase play a role in the development of bladder cancer. The first demonstration of ras as an oncogene was in bladder cancer cell line, but ras and other dominant cancer genes are infrequently involved.
Non muscle invasive tumours that show loss of heterozygocity in the long arm of chromosome 9 has a favourable prognosis.
Loss of tumour suppressor genes pRB and p53 is associated with invasive tumours and has a poor prognosis.
What measures are used in the primary prevention of bladder cancer?
Avoidance of tobacco smoke and occupational exposure to carcinogens such as nitrosamines, avoidance of water polluted with chemicals such as arsenic, and, where possible, limiting exposure to pelvic radiation.
Prompt treatment of UTI, removal of calculi and avoiding prolonged indwelling devices (such as catheters) can reduce inflammatory causes of bladder cancer. Limiting use of cyclophosphamide and minimising exposure to radiation can reduce iatrogenic causes.
Metformin, which potentiates the anti-cancer effect of chemotherapy and radiotherapy, is reported to significantly reduce the incidence of bladder cancer.
Is there currently a screening programme for bladder cancer?
Bladder cancer is not currently screened for. However, one study looking at long term screening for bladder cancer using haematuria dipstick showed the mortality was 0% in the screened vs 20% in the registry groups when comparing stage at presentation.
Are there any secondary preventative measures useful in bladder cancer?
High dose vitamins A, B6, and C are reported to reduce recurrence.
What are the key diagnostic factors in bladder cancer?
The first key diagnostic factor is to consider the presence of risk factors for bladder cancer (i.e. male sex, family hx, tobacco smoking, chemical exposure, pelvic radiation, systemic chemotherapy, age >55).
Gross or macroscopic haematuria is the most common presenting complaint in bladder cancer in >80% of patients. Gross painless haematuria occuring throughout the urinary stream is most common. But episodes are typically intermittent and therefore resolution should not be attributed to treatment, with e.g. antibiotics.
Dysuria is also a common feature but is usually associated with aggressive bladder cancer such as high grade urothelial carcinoma or CIS. In the absence of infection to account for the dysuria, cytology is key and is positive in up to 90% of patients.
What is the most important first line investigation in suspected bladder cancer? What is second line?
Urinalysis is the first line investigation. Gross (macroscopic) haematuria is the presenting complaint in 80% of cases. It is also important to assess for dysuria (burning pain on urination) and urinary frequency (rarely the sole symptom in bladder cancer).
Cystoscopy is second line for bladder cancer. Remember low grade tumours are papillary and easy to visualise, but high grade tumours are often flat or in situ and difficult to visualise. If a patient undergoes cystoscopy and a lesion is suspicious of a urothelial tumour then they should be rescheduled for a TURBT which allows the diagnosis to be confirmed pathologically and the extent of the disease assessed.
What features are suggestive of a non muscle invasive tumour on cytoscopy?
Include papillary tumours with a fine stalk (Ta) or thick stalk (T1). Rough erythematous patches can be indicative of Tis (carcinoma in situ), although urothelium often appears normal. Staining biopsies with 0.2% methylene blue is required to confirm Tis.
What are features suggestive of a muscle invasive tumour on cystoscopy?
Multifocal tumours that are sessile. Vascularity around the tumour is increased. Tumours are often large. Bimanual examination may reveal tumours that have progressed beyond the lumen of the bladder.
What should happen if the visual appearance of the lesion suggests it is non invasive disease?
The patient should undergo imaging of the upper tract if they have not already done so. This can be by intravenous pyelogram, CT urography or renal ultrasound with retrograde pyelography. This should be followed by a TURBT.
What should happen next if the visual appearance of the lesion suggests it is muscle invasive?
Patients should have FBC, U&E, chemistry profile (including alk phosphastase), CXR, imaging of the upper tract collecting system, and abdominal/pelvic CT or MRI before TURBT. A pelvic CT is best performed before TURBT if a high grade lesion is suspected because surgical changes can be confused with extravesical extension. If the alk phos is raised then the patient should have a bone scan.
What is important when performing a TURBT?
Biopsy fragments must be of adequate size and depth to allow for proper assessment of detrusor muscle involvement. Muscle invasive tumours cannot be reliably resected transurethrally and are generally best treated by radical cystoscopy.
What does carcinoma in situ increase the risk of?
Bladder Tis increases the risk of upper tract and urethral carcinoma. Carcinoma of the prostatic urethra, if untreated, can progress to active invasive disease. Early invasion of the prostate may be managed by TURP if the resection margins are free of disease, but deeper invasion carries a poor prognosis.
Are there any urinary markers for bladder cancer?
Cytology is the accepted urinary marker for bladder cancer, but it can have false negatives. Additional markers are available (e.g. dipstick for haematuria) that have increased sensitivity but this comes at the expense of reduced specificity. These new marks also include bladder tumour antigen (BTA), nuclear matrix protein 22 and others.
How does bladder cancer spread?
Bladder cancer can spread by:
1) Direct invasion - the TNM classification system is used widely to stage bladder cancer. The p stands for pathology, T for tumour and the letter or number for the degree of spread
2) Lymphatic - common in fatal cases to iliac and para-aortic lymph nodes
3) Haematogenous - a late phenomenon with metastases to liver and lungs most frequently
4) Implantation - may occur at cystectomy with implantation in the prostatic bed, urethra and scars in bladder or abdominal wall
How are bladder tumours classified?
Bladder tumours are classified based on their macroscopic appearance, microscopic appearance (grade) and the degree of spread or staging (TNM).
What are the macroscopic features of bladder tumours?
Bladder tumours come in a number of shapes that are visible on cystoscopy (i.e. with the naked eye):
1) Papillary - fronded masses growing into the lumen with little or no invasion of the wall (commonly low grade)
2) Solid - tumour growing directly into the bladder wall with little or no projection into the lumen. These are often ulcerated or encrusted.
3) Papillary and solid - mixture of 1 and 2.
4) Flat in situ carcinoma - a distinct form of surface malignancy causing reddening of the bladder mucosa due to underlying telangiectatic blood vessels
Most solid tumours are invasive from the outset and only a small percentage of papillary tumours evolve into invasive carcinoma. A significant portion of in situ carcinomas become invasive and patients with this condition need careful follow up, such as cystectomy, if required to prevent spread.
What system is used to grade bladder tumours?
Grading refers to the microscopic appearance of the tumour. The most common grading system is the WHO 1973 grading system which grades tumours from I to III according to the degree of differentiation:
1) Papilloma - papillary growth with no significant stroma, the urothelium of which is indistinguishable from normal
2) Well differentiated (grade I) TCC - vast majority are papillary growths with no evidence of invasion. Fronds of the tumour have more cell layers than normal urothelium and cells have slightly larger nuclei than normal
3) Moderately well differentiated (grade II) TCC - usually papillary in which a significant number are invasive at presentation or become so. The cells of the fronds are atypical with an increase in mitotic figures
4) Poorly differentiated (grade III) - least likely to be papillary, almost all are solid extensively invasive tumours. The cells are pleomorphic with numerous mitoses and may be difficult to recognise as being urothelial in origin.
What is the TNM classification system? What tumours under this system are considered non muscle invasive?
This is the staging system for bladder cancer (cancers are both graded AND staged).
T = tumour
N = nodes (biopsy)
M = metastases (imaging/ examination)
pTa = no invasion
pTis = carcinoma in situ
pT1 = invasion confined to the lamina propria
pT2 (a + b) = extension into muscle
pT3 (a + b) = extension into perivesical tissue
pT4 = extension beyond muscle (e.g. into prostate, uterus, vagina, pelvic wall)
Under this system the following tumours are considered non muscle invasive:
- papillary tumours confined to the epithelial mucosa (pTa)
- tumours invading subepithelial tissue (lamina propria) (pT1)
- Tis (carcinoma in situa)