July is Bladder Cancer Awareness Month; Dr Chan updates us on all the need-to-know-bladder-cancer-info in the year 2017.
Bladder cancer is the most common malignancy involving the urinary system. It is the ninth most common malignancy worldwide. There are two broad types of bladder cancer: urothelial and non-urothelial.
Urothelial bladder cancer
This is the commonest histologic type in the Western world, consisting of more than 90% of all bladder cancer. More than 50% of patients with urothelial cancer are cigarette smokers.
Occupational exposure to the chemical carcinogen (the aromatic amines) is also another risk factor for bladder cancer. Common industries and jobs associated with these carcinogens are painters; printing, textile, carpet, dye, rubber and leather workers; hairdressers; metal workers; and operators of excavating machines.
If these workers smoke, the risk of bladder cancer increases further on top of these occupational exposure. Urothelial bladder cancer is three times more common in men than women. It is seen mainly in older adults.
Non-urothelial bladder cancers
These are more common in some parts of the world such as the Middle East, where schistosomiasis (or bilharzia) is prevalent.
Many bladder cancer patients do not die of their disease but do have multiple recurrences, and because of this, bladder cancer is the second most prevalent malignancy in adult men, after prostate cancer.
The reason for many recurrences is thought to be an effect of the entire urinary tract (the urothelium) being exposed to carcinogens that are excreted in the urine. This explains why bladder cancer can recur in another part of the urinary tract, such as the ureter or renal pelvis, and why bladder cancer is frequently multifocal. Increasing fluid intake may dilute excreted urinary carcinogens and reduce the contact time with the urothelium by frequent urination.
The bladder is predominately muscle; it stores urine and can expand and contract. When cancer first develops, it starts growing from the inner layer of the bladder (urothelium). Initially the growth is superficial and not involving the bladder muscle, a term called ‘non-muscle-invasive disease’.
If left untreated, it will then grow outwards and invade deeper into the muscle layer. We then call the cancer ‘muscle-invasive’. When this uncontrolled growth continues, it can spread to other parts of the pelvis locally, or spread to other parts of the body, such as bones, lungs, and liver (Stage IV or metastatic stage).
Clinically, patients usually present with painless haematuria (blood in the urine). They can also present with increasing urinary frequency, pain when passing urine or lower abdominal pain in advanced disease, or constantly having the urge to urinate. These symptoms are very similar to urinary infection or prostatitis, so the diagnosis is sometimes delayed, leading to more advanced stage at diagnosis and therefore, poorer survival.
Usually, patients present to their local GP with unexplained or recurrent haematuria. They are then referred to a urologist for a full evaluation of the problem. A comprehensive urine analysis, cystoscopy, and radiological imaging will be done. A biopsy confirms the diagnosis.
Staging and treatment
After confirmation, it is vital to determine the stage of the cancer. The staging gives us the expected prognosis and it will guide treatment decision. For example, muscle-invasive disease usually means a cystectomy (complete removal of the bladder) is necessary, and pre-op chemotherapy will improve the response and cure rate of the cancer.
In Stage IV or metastatic disease, the main aim of treatment is to maintain the quality of life (palliation). At present, platinum-based chemotherapy is the standard of care. However, there are rapid developments of immunotherapy to treat bladder cancer. Available treatments include anti-PD1 and anti-PD-L1 inhibitors, such as pembrolizumab and atezolizumab.
These work by ‘correcting’ the immune system to fight the cancer. Recent research also showed that these immunotherapy work best if there is a ‘genetic defect’ within the cancer, called microsatellite instability or DNA damage repair (DDR) gene alternation.
Researchers throughout the world are busy analysing the genes within the cancer to unravel the mechanisms of why the immune system could not kill the cancer, and investigating ways to ‘switch’ the immune system back on again to fight the cancer.
Participating in immunotherapy trials for bladder cancer is available in South Africa. Be sure to ask your doctors about new treatment opportunities.
MEET OUR EXPERT – DR SZE WAI CHAN
Dr Sze Wai Chan is a medical oncologist at Sandton Oncology Centre. Her major interest is in the latest developments in cancer treatment. She is also involved in clinical research both locally and internationally.