That this could be diagnostic for some / all other type of solid tumor cancers can't be ruled out by this study, as published. If they study had included diagnostics for every other type of cancer and showed them to be negative, then we could draw the conclusion it's specific to OC.
I wonder if they will have to do separate studies for each type of cancer or what/how many studies would be required for it become the standard tool for all solid cancers? Just musing...