Conventional cancer drugs are toxic to both tumour and other normal tissue and so are often associated with significant side effects. Recently, novel drugs which selectively target tumours have been developed. For such drugs (biologically targeted anticancer drugs), the clinical effects are observed at doses below the toxicity levels. Therefore, the side-effects are significantly reduced compared to conventional chemotherapy. A major challenge in using these targeted drugs however is determining the right dose to use for optimal clincial effect. Since certain molecules targeted by the drugs are also present in skin, we propose to monitor the molecular changes in the skin to assess the efficacy of these novel drugs. We will use a non-invasive optical method (Raman spectroscopy) to detect molecular changes is the skin of patients without need of biospy.If successful this would be a very useful method in the development and clinical use of such drugs.