To ensure the integrity of document, you can consider adding a digital signature to Word documents. The digital signature will be invisible and will not allow to edit the document making it locked. The locked document can be unlocked, but doing this will make the digital signature invalid. So this process ensures that your document is not tampered with.
To add a digital signature, click on the Office button on the top left corner of word and select Prepare. Inside Prepare menu, select Add a Digital signature option.
Once the option is selected, you get a warning and here you can either get digital signature from 3rd party or use the default one from Microsoft. The default one does not provide any warranty as it has legal enforceability in different countries.
Click on OK to select the default signature. If the document is not saved, then it prompts to save the document. Next you can add the purpose of signing the document.
Click Sign button and the signature will be created. You can view the digital signature from the same menu (Prepare-> View Digital Signatures). This will be available as a sidebar.
If any edits are made to the document, then the signature will become invalid.