I am not licensed in your state but can give you general advice. Medical neglience occurs when the treatment rendered (or not rendered) falls below the standard of care expected of the reasonable doctor. One of things that a local lawyer will want to know is how your condition is different long term than it would be if you had received the appropriate treatmetn at an earlier time. Your damages must be catastrophic in order to pursue a claim because the cost of retaining medical experts is very costly. Call a local lawyer who can review your potential claim.
I assume you are saying you have been diagnosed with bladder cancer. You had sought a partial bladder removal and chemo but a physician wanted you to undergo radical (total) bladder removal. You got a second opinion and indeed discovered that a partial removal would suffice.
In a case like this, keep in mind that your damages would only be limited to what the delay (if any) in definitive treatment caused you. And you bear the burden of proof. So let's say this doctor may have cost you a month or two in delayed treatment of bladder cancer. My experience with this type of cancer suggests that this kind of delay could never, ever be proved to have made a difference in your treatment plan and prognosis. If you had a year of delay, it might be different.
You should probably have phone conversation with a malpractice attorney in your state. talk about your statute of limitations and the key dates in your case.