Yes, cytokines can be used in cancer therapy. This form of treatment is known as cytokine therapy. For example, interleukin-2 (IL-2) has been used to treat kidney cancer and melanoma. Interferons (particularly interferon-alpha) have also been used to treat cancers such as hairy cell leukemia, chronic myeloid leukemia, and malignant melanoma. These treatments aim to boost the immune system's ability to fight cancer.