She went to a UC (Davis)... remember she's in her late 40s/early 50s now. What I'm telling you is it's not rare. I know a lot of sub-26 cancer doctors that are at Dana-Farber and Stanford... also know several at MSK, MD Anderson and several other top cancer hospitals... obviously, I'm only aware of those that shared what they got on the MCAT... some how they all seem to remember, especially those with lower MCAT scores and the low MCAT folks are happy to talk about how they score low on the MCAT and made a come back to score high on Step 1... one even scoring in the 270s after a sub-25 MCAT (I have only worked with cancer doctors... I'm not implying cancer docs have lower MCAT scores... just for the record).
The MCAT has NO correlation AT ALL with how good a physician you will become. The only correlation is to how well you'll do on Step 1 (and surprise, surprise, step 1 doesn't correlate much with clinical medicine... it tests your knowledge of basic sciences). Also, the correlation between MCAT and Step 1 is far from perfect. The MCAT absolutely and definitively ONLY tests ONE thing AND that is HOW WELL YOU CAN DO ON THE MCAT.
It's like looking at an LSAT score and trying to correlate it with whether you'll be a good doctor (again no correlation between the LSAT and whether you'll be a good doctor or lawyer for that matter (its supposed intent)). The likelihood of someone with a 19 and a 39 hurting their patients is the same (incompetent people will be incompetent no matter how well they do on the MCAT). Whether or not they can recall that an SN2 reaction takes place in aprotic solvents probably won't make them an amazing physician all of a sudden.
The exam that would prove whether or not you are competent as a physician is the board exam. If you are board certified then you are more likely to be a good doctor in that specialty. That's why if you ever look at various hospital websites, they will always say to ensure that your physician is board certified in that specialty and not to ensure your doctor scored above 30 on the MCAT.
Thanks to good old Moss, we are all stuck with the MCAT. Take the Moss Test (what the MCAT was called originally) for fun if you locate it (I can't seem to). Back in the day the topics tested included visual memory, memory for content, scientific vocabulary, scientific definitions, understanding of printed material, premedical information, and logical reasoning and surprise, surprise it was criticized at the time for testing only memorization ability and thus only readiness for the first two years of medical school and showed no correlation to whether or not you'd become a competent doctor. Continuation of a 1920s argument here.
Finally look for the signature of Berkeley Review Teacher (someone who did well on the MCAT) and see what type of people he/she thinks become good doctors.
What school accepted her?
Also, you will always find the rare exception of a person that could not perform well on the MCAT and ends up doing well as a physician. Just as you would find that rare exception to a lot of things. The question is, how would adcoms know if that applicant with a 19 on their MCAT would be suitable to practice medicine, let alone become one of the most famous cancer doctors? What if that 19 MCAT applicant is accepted and harms patients because they lack basic aptitude?