I may be passing on something that you all already know about - but just in case thought I would post a link for people to check out.
In particular, the thorny issue of the classification of our blood conditions as a rare cancer - as obviously, there are still medical practitioners who do not believe that MPNS are a form of cancer. This seems to show that as far as Cancer Research UK are concerned MPN'S should be regarded as such.
The link takes you to Myeloproliferative neoplasms, with further links to the individual conditions:
Hope you find this useful, particularly when wanting to explain to others what your condition is all about, in fairly simple terms.