MMR stands for mismatch repair, which is cellular system for repairing a type of DNA damage that occurs normally in cells as they divide. All cells in our bodies carry out MMR. "MMR proficient" means that the mismatch repair system in your tumor is normal. Since this is the normal state, there are no clinical implications for the tumor being MMR proficient. (There would be clinical implications if the tumor were "MMR deficient," ie having defective mismatch repair. About 25% of endometrial cancers are MMR deficient, and testing for MMR is standard of care for endometrial cancers. )

The BRAF test is strange, and it makes me wonder if there's been some sort of miscommunication. I'm almost reluctant to comment on it, and you should definitely ask the doctor about it.

BRAF is a gene that is frequently mutated in certain types of cancers. As of 2 years ago, when I quit my hospital job, it was routine to test for BRAF mutations in certain thyroid nodules, in colorectal and lung cancers, and in melanomas. I see no reason to test an endometrial cancer for it, unless they just routinely do the test on every sample they get, which I guess is possible. BRAF mutations are extremely rare in endometrial cancers; the NCCN guidelines don't recommend or even mention testing for it; and BRAF testing is definitely NOT standard of care.

What would be standard of care would be to test for a different gene called p53. Does the report mention that?

The phrase "BRAF positive" would normally mean that your tumor has a mutation in the BRAF gene. But I am reluctant to draw that conclusion in your case, since that seems extremely unlikely. More likely some kind of miscommunication. I certainly wouldn't spend any time worrying about it either way, but I would ask.

I hope that answers your questions. (I know this is obvious, but let me add the disclaimer that I am a random stranger on the internet, and everything said by such people, no matter how sincere, should be taken with a grain of salt.)