I have never considered Epicurean philosophy to be a form of "Humanist" philosophy any more than it is a form of Stoicism or Platonism. I haven't written extensively on this, in part because many Humanists are allies on certain important points, such as rejection of Supernatural Religion.
But I was reminded of this point today and I think it is time to start a thread on it. My position is that "Humanism" is just another "-ism" that has a goal at its center which is very different from Epicurean philosophy. It will take much citation and explanation to explain this, but let's start in this post with the frequent Humanist slogan:
"GOOD WITHOUT GOD"
That should be an immediate tipoff that feeling - pleasure and pain - are not at the center of Humanism. What's at the center is "being good." And advocacy of being a good person is always a tipoff that the person advocating that position has his or her own definition of "What a Good Person Is." And therein is the slippery slope of all Idealist philosophies and religions: In the atomistic universe recognized by Epicurus, in which there is no center point of observation, no supernatural creating god, and nothing eternal except elements and void - there IS no single definition of "good."
I will come back to this as time allows, because I know my criticism of "Humanism" is not unique, nor is it rooted only in Epicurus or even in Nietzsche. I don't consider this issue to be a word game, and I consider it important not to unnecessarily offend the many good people who embrace the term "humanism" for reasons that are compatible with Epicurus.
But Epicurean philosophy is about being precise with words, and keeping Nature - not idealism - at its center, so this is an issue which needs to be developed and understood.
I fully agree with this reference to Nietszche as recorded at Wikipedia: "For Friedrich Nietzsche, humanism was nothing more than an empty figure of speech – a secular version of theism."
Here is a useful Wilipedia article as a starting point for reference.
Here is an article at Academia.com: Nietsche's Overcoming of Humanism ["In this section, I will discuss the transition from Platonic-Christian values to the values of secular humanism and attempt to show how these values, from a Nietzschean perspective, constitute another instantiation of the nihilistic paradigm"]