Yes, it it already well-known that generation of free radicals is part of a normal immune response[1]. Basically, certain immune cells go into an inflamed area and start generating and releasing as many free radicals as they can in order to cause maximum damage. So if that particular immune mechanism is important in the body's response to cancer, then taking excessive antioxidants could plausibly impair the body's ability to fight cancer.
My understanding of the case against antioxidants is that thefree radicals (etc.) are an essential cell signaling mechanism ... and the signal is "kill me, I'm a bad cell".
If you somehow disrupt or eliminate the signal, you allow bad, or inefficient, or perhaps cancerous cells to live longer than they would otherwise.
I'm paraphrasing directly from the excellent, excellent book _Power, Sex, Suicide: Mitochondria and the Meaning of Life_ by Nick Lane, which is highly skeptical of antioxidant supplementation and is a truly fascinating book.
Another theory, which i think is interesting is that free radicals damage strong as well as weak cells, those weak cells that are killed by free radicals could actually more easily transition into cancer in the absence of free radicals.
It is too easy to explain less free radicals as good. There isn't a single variable in this equation.