Patient info documents: American versus British spellings?

“Tumor”, “diarrhea”, “estrogen”, "hemoglobin… "
If you have noticed American spellings in any documents you’ve received from your (UK) hospital - especially if you are participating in a clinical trial or other research - do you have any views about this? Just wondering…

My breast care nurse told me that she had to work hard to train herself to stop being irritated everytime she saw/heard the term ER+ as to her it should be OR+.

Myself, at times I am a member of the spelling/grammar police (although not on the internet as so many here are using English as a second language and anyone can make a typo). However in the scenario you describe if it was an american based trial I would let it go, but if it was English I would be sorely tempted to return the documents with corrections in red pen!!