4. Terminology
4.1 Intravesical instillation
Intravesical instillation is a procedure by which fluids are slowly introduced into the bladder via a catheter and allowed to remain there for a specific length of time before being drained, voided or withdrawn. The procedure is performed to expose the tissues of a given area to the solution. This procedure enables drug delivery to the urothelium with reduced systemic side effects compared with oral or parental drug delivery [10]. The procedure is also referred to as ‘bladder instillation’, ‘intravesical treatment’ and ‘intravesical therapy’. These Guidelines use the term ‘intravesical instillation’.
4.2 Intravesical chemotherapy
Intravesical chemotherapy is intended to eradicate any surviving cancer cells in the bladder mucosa (so-called ’chemoresection‘ of the tumour) and, in case of immediate postoperative instillation, to destroy any floating tumour cells left behind by transurethral resection of the bladder tumour (TURBT) and prevent those floating tumour cells from implanting.
Mitomycin C (MMC) is a chemotherapeutic agent that inhibits DNA synthesis in tumour cells. MMC decreases the recurrence rate from 54% to 38% but has no impact on the risk of progression [11]. Other intravesical chemotherapeutic agents exist apart from MMC. Doxorubicin, epirubicin and thiotepa are used in some countries, however, the superiority of one drug over the others has not been demonstrated [12].
4.3 Intravesical immunotherapy
Immunotherapy aims to eradicate disease by provoking or enhancing the host immune response. Bacillus Calmette-Guérin is a live-attenuated strain of Mycobacterium bovis. When instilled into the bladder, Bacillus Calmette-Guérin triggers an immune response in the mucosa that eventually kills cancer cells. Immunotherapy aims to eradicate disease by provoking or enhancing the host immune response. BCG is a live attenuated strain of Mycobacterium bovis. When instilled into the bladder, it triggers an immune response when binding to fibrinogen in the bladder wall. It works in two ways; it has a direct cytotoxic effect as well as activating a variety of different immune cells, both of which results in killing of remaining tumour cells in the bladder. in the mucosa that eventually kills cancer cells . Bacteria in the suspension attach to the tumour cells and are absorbed. Consequently, immune cells such as granulocytes, macrophages and lymphocytes move into the tissue as a part of the inflammatory reaction, leading to tumour elimination. The less differentiated (i.e., more aggressive) the tumour, the more sensitive it is to BCG [13].
As discussed in the EAU Guidelines on NMIBC, studies have shown that BCG after TURBT is superior to TURBT alone or TURBT plus chemotherapy for preventing the recurrence of NMIBC [14].
A Cochrane systematic review confirmed that BCG is more effective in reducing the recurrence rate over MMC [15].