Malignant tumors of the urinary bladder tend to recur at the same site or elsewhere in the bladder as a so-called recurrence. Instillation therapy aims to prevent recurrence or progression of bladder cancer after surgical removal (TUR-B). It is also used for tumors that have already grown into the bladder muscles at the time of initial diagnosis (muscle-invasive bladder tumor).
Two drugs are available for instillation therapy: Mitomycin C and Bacillus Calmette-Guerin (BCG), which can be delivered directly into the bladder via a small catheter.
Mitomycin is an antibiotic, but is now used only as a cell-destroying tumor drug (cytostatic). It is used for tumors with a medium risk and is applied 1x a week for 8 weeks and then 1x a month. For smaller tumors, it can also be instilled immediately after surgery. This can reduce the risk of recurrence by up to 40 percent.
Bacillus Calmette-Guerin (BCG)
BCG was originally developed for vaccination against tuberculosis. It triggers an inflammatory reaction of the mucosa in the bladder, which has an antitumor effect. The difference with mitomycin is that BCG is used for tumors with a higher risk. It is applied weekly for 6 weeks. This is followed by a cystoscopy with biopsies taken from the mucosa. If no further tumor cells are found, the intervals are increased to 3 months and subsequently to half a year.
Both drugs have relatively few side effects. However, with BCG, irritation of the bladder with urinary urgency and burning, as well as inflammation and fever, sometimes occur. Which drug is used for which patient must be decided by the attending physician together with the patient in each individual case, depending on the degree of risk of the carcinoma, the side effects and intolerances.