This is an interesting hand drawn cachet.  It appears to have been created by the addressee, Hazel A. Herman of Toledo OH.  She even signed the cachet.  As you can see, it features an ink drawing of an upside down Sword of Hope and the text "Crusade Against Cancer".  I don't know if Mrs Herman added this drawing to the cover when the stamp was first released or several years later.  I suspect that the cachet is not an add-on, but I have no way to confirm that.  If it is an add-on, it's not a recent one.  The ink looks old and faded.  I believe that it is probably a one-of-a-kind cachet.  If you can provide any other information about the cachet or Mrs Herman, please drop me a line at smith@in.net.