This might help you to understand easier. This gives you a quantitative comparison if BCG or intravesical chemotherapy (MMC) will improve your recurrence problem.
Open this link. You will see the recurrence risk and progression risk of non-muscle invasive bladder cancer.
This calculator is based on a large study done by European Organisation for Research and Treatment of Cancer.
www.evidencio.com/models/show/1025
Select as below for your case.
Number of tumor : 2 to 7
Tumor size: < 3cm
Primay recurrence rate: > 1 rec /yr
Ta category: Ta
CIS : No
Grade : 1
There is 38% chance that you will have another recurrence within 1 year
There is 62% chance that you will have another recurrence within 5 years
There is 1% chance that your cancer progresses within 1 year
There is 6% chance that your cancer progresses within 5 years
So, based upon your history, you will have 38% chance of recurrence within 1 year.
But there is only 1% chance for progression.
Now the question is how much will BCG and chemotherapy ( or intravesical chemotherapy) reduce recurrence in your case. Since Mitomycin is used often for this type of intravesica chemotherapy according to several studies, Mitomycin. What is the difference in efficacy and side effects between BCG and Mitomycin.
There was another study done in Europe in 2009, involving 2839 patients. 54% was Ta and 43% was Ti. G1 was 58%, G2 16%, G3 7%. Your case is TaG1. I did not get a detail report because it costs $US 35, but the summary of the study says with a median follow-up of 4.4 yrs after BCG and Mitomycin, 43% recurred. Overall there was no difference in the time to first recurrence between BCG and MMC. The link to the study is listed at the end.
So, statistically speaking, you should expect the improvement recurrence from 62% within 5 years to 43% per in the same period if you will have BCG or MMC therapy. It does not mean that you will have 43% in 5 years even after BCG or MMC treatment, but it is rather a yardstick to review what should be the next treatment for you.
Cancers are caused by mutations of multiple genes in DNA. Bladder cancers are known as heterogeneous. There are hundreds of gene mutations have been found in bladder cancers. I recently attended a talk by a scientist who had done a study of genome analysis of non-muscle-invasive bladder cancer. He checked genomic sequence of 80 NMIBC patients and found not two persons had exactly the same combination of gene mutations.
This is one of the reasons why a certain treatment works for some people and does not work for others even though.
www.europeanurology.com/article/S0302-2838(09)00434-5/abstract/an-individual-patient-data-meta-analysis-of-the-long-term-outcome-of-randomised-studies-comparing-intravesical-mitomycin-c-versus-bacillus-calmette-gu-x000e9-rin-for-non-x02013-muscle-invasive-bladder-cancer#%20