Hi Ibar
Welcome to Neurotalk (NT) - Sorry to read that you've joined us because of SFPN. I don't have the medical knowledge to say specifically that it is caused by the alpha interferon therapy but it's possible there's a connection. Both cancer itself and many of the various treatments used can cause PN.
Given that there is over 100 different types of PN, and just as many causes trying to find the exact cause can be difficult.
Here's a couple of links to sites that have some useful info:
Peripheral Neuropathy Fact Sheet | National Institute of Neurological Disorders and Stroke
Cleveland Clinic:
Peripheral Neuropathy
(Note that "interferon alfa" is listed in the miscellaneous section of Table 1: Drugs that Can Induce Polyneuropathies)
Hope this is of some use in your search for answers. All the best for managing your condition. You can use the search function on this site to find many posts by others who have discussed ways to improve their PN. Please feel free to ask more specific questions and others may be able to help.