I just answered my own question, since I had the MS report in Word.
I was hoping I'd have to supply a password to edit it, which would be a somewhat reasonable level of security. But no; you just click "edit anyway." Duh.
Unforunately, being able to read the document is already sufficient access to make your own copy and alter it however you please.
The best you can do is a digital signature[1], which proves that the document has not been tampered with. Of course, it's up to the recipient to ask for a signed document and to actually check if the signature is still present and accurate upon receipt. Otherwise, it's very trivial for a third-party to remove the signature and add their own edits.
In some pdf readers there is an option "respect limitations"… by disabling it you can print even when print is disallowed and so on. I guess it's the same with word documents.
I have no idea how hard it is to get around that, but probably too hard for most headhunters.