Neither Homeopathic nor Herbal remedies are considered appropriate cancer treatment. There is no biological mechanism for them to have an effect greater than a placebo, so studies on such products are not something researchers would be interested in.
However, it is well known that determination to beat cancer does actually correlate with beating cancer.
Given that there is an immune system -mind interface that is poorly understood. This could make the immune system more effective through the person's belief.