Retinoids These are synthetic and natural derivatives of vitamin A. Patients with vitamin A deficiency may have an increased susceptibility to skin cancer. This deficiency causes a premalignant change of the skin that can be reversed by applying vitamin A.
Retinoids induce differentiation (maturing) of tumor cells derived from surface tissues (epithelium). Recent investigations have used the retinoids to treat premalignant and malignant skin cancers. Use of the locally applied (topical) and internal (systemic) forms have demonstrated a fair cure rate when treating basal cell cancers. Limited information exists for use in SCC, but one study reported a 70 percent response rate.
Interferons Interferons are proteins produced by human cells in response to a viral infection. Interferons have an antiviral activity, they inhibit the growth of malignant cells and they promote cell maturation. There are three interferons— alpha, beta and gamma.
• Interferon-alpha is found in T and B lymphocytes and in macrophages .
• Interferon-beta is found in fibroblasts (connective tissue producing cells).
• Interferon-gamma is found in activated T cells.
Interferon-alpha has been the most frequently studied interferon for use with skin cancers as well as other types of cancer. Preliminary reports have shown significant results in short-term remission of basal cell carcinomas when interferon-alpha is injected into the tumor (intralesional injection). Interferon is also effective
