Hi Sherry and welcome to Mayo Connect. Small fiber neuropathy (SFN) can be associated with many medical conditions. It occurs as a result of damage to the small fibers of the peripheral nervous system brought on by inflammation.
Some of the causes of SFN include underlying health conditions such as: metabolic and endocrine disorders, autoimmune diseases, vitamin deficiencies, chemotherapy, to name a few. If this is directly related to your cancer or not would be a good question for your oncologist.

This article from medicalnewstoday.com does a great job explaining SFN.
https://www.medicalnewstoday.com/articles/small-fiber-neuropathy
But my goodness, you’re downplaying the report of your doctor yesterday that you have been diagnosed with cancer. I’m so glad you came to Mayo Connect. We have many amazing support groups in the forum with members who have faced pretty much every diagnosis. We’re here to walk you through this.
So that I can connect you with someone who has received similar news, would you mind sharing what your type of cancer you have?