Approximately 80% of metastatic cell carcinomas of the bladder are superficial, presenting as papillary confined to the mucosa (Ta) or involving the lamina propria without affecting the muscularis (T1) and as flat, non-papillary carcinoma in situ (Tis) or interstitial lesions.
The currently accepted treatment of choice is local excision of the tumor and/or intravesical perfusion therapy.
Recurrence is highly likely after surgery, and the recurrence rate of Ta and stage T1 tumors varies from about 40% to 80% after the first local excision.
Since the application of cytotoxic drugs more than 30 years ago and BCG as intravesical instillation therapy 20 years ago, the recurrence rate of superficial bladder tumors has decreased significantly.
The current hot spots of interest are briefly described as follows.
I. Preventive and therapeutic effects of intravesical instillation therapy with different drugs
The purpose of applying intravesical instillation therapy after local tumor resection is to reduce tumor recurrence and prevent the progression of lesions in case of recurrence.
Currently, commonly used cytotoxic drugs such as mitomycin C, adriamycin, tiotepe and BCG of immune agents have preventive effects on tumor recurrence, among which BCG is recognized to be more effective. controlled comparative studies have shown that BCG is significantly more effective than tiotepe and adriamycin in reducing tumor recurrence and preventing lesion progression.
Other immunotherapeutic agents such as KLH, α-interferon, Bropirimine, TNF, LAK/IL-α, TIL, etc. have also been gradually used in clinical practice, and their toxic effects are lower than those of BCG, but so far, they have not been found to be more effective than BCG.
BCG is also more effective than cytotoxic drugs in the treatment of carcinoma in situ or interstitial lesions.
II. Problems related to BCG intravesical infusion
(A) The effect of BCG intravesical instillation has been recognized, but there are still many issues that need to be clarified and unified. In particular, the ideal strain, the determination of dose and duration of treatment, the mitigation of toxic reactions, etc.
1, strains: different BCG preparations do not contain exactly the same amount of bacteria, and so far, the differences in efficacy between different strains are not statistically significant.
2, dose: the ideal dose should be able to obtain the maximum therapeutic effect and reduce the toxic and side effects to a minimum. There is no definite conclusion yet.
3.Protocol: There are many different protocols for BCG prophylactic perfusion. Most of the current opinions prefer that maintenance therapy should be continued after 6 weeks of induction therapy.
The ideal treatment regimen is yet to be further defined. An initial 6-week standard treatment followed by a gap of 3 months followed by 1 weekly treatment for a total of 3 sessions has been shown to significantly improve treatment outcomes.
(ii) The issue of re- and multiple treatments with BCG intravesical instillation
The results of multiple applications of BCG show that repeated multiple treatments with no more than 3 times are appropriate and the overall efficiency can reach 90.7%.
(iii) BCG combination therapy
Combined application of different chemical drugs and immune agents to improve the efficacy and reduce drug toxicity is the general trend of tumor treatment.
The results showed that the combined application of MMF and BCG by sequential method improved the efficacy with no increase in adverse effects.
III. Treatment options for superficial infiltrative tumors (T1N0M0)
The choice of treatment for stage T1 tumors, especially T1G3, is sometimes a difficult dilemma to choose.
There are two tendencies at present.
1.After local tumor resection, irrespective of its grading level, intravesical irrigation therapy should be performed first, and then further treatment plan should be decided according to pathological examination results and later urine cytological examination results;
2.After waiting for the pathological results, once the tumor is identified as G3, total cystectomy should be performed as soon as possible.
3. A lot of data show that recurrent tumors are treated again or more times with satisfactory results, especially BCG treatment has long time effect. Therefore, close follow up should be done.