Conversely, this high bar makes it very difficult to improve on invasive but adequate treatments. Consider mastectomy for early-stage breast cancer: it works pretty well, and that makes it damned near impossible to test any alternative treatment that might work just as well or better, and which would certainly be less invasive.
We already do. It's called "lumpectomy with sentinel node biopsy" for small enough tumors. No need to take off the entire breast.
I worked on a cancer-therapy project once and had the clever idea of applying the technique we were using--which was aimed at something that was incurable at the time--to certain kinds of breast cancer, which was just similar enough to be an interesting candidate for the technique. I talked to a breast cancer researcher and he said, "That's a really clever idea. It sounds plausible. I can't do anything with it." And then explained the above reasoning.
This means that we tend to focus on treatments for currently untreatable cancers, and once we have something that is semi-OK, the rate of improvement goes way down. It doesn't go to zero, by any means, but the incentives shift in a way that is both perfectly logical and kind of perverse.
What technique were you doing? Surgical? Medical?