Radiotherapy, frequently used for treatment of solid tumors, carries two main obstacles including acquired radioresistance in cancer cells during radiotherapy and normal tissue injury. Phenylpropanoids, which are naturally occurring phytochemicals found in plants, have been identified as potential radiotherapeutic agents due to their anti-cancer activity and relatively safe levels of cytotoxicity. Various studies have proposed that these compounds could not only sensitize cancer cells to radiation resulting in inhibition of growth and cell death but also protect normal cells against radiation-induced damage. This review is intended to provide an overview of recent investigations on the usage of phenylpropanoids in combination with radiotherapy in cancer treatment.
Antineoplastic Agents/*therapeutic use ; Apoptosis/drug effects/radiation effects ; Chromones/therapeutic use ; Combined Modality Therapy ; Cytoprotection/drug effects/radiation effects ; Humans ; Neoplasms/pathology/*radiotherapy ; Phenylpropionates/therapeutic use ; Plants ; Radiation Tolerance/drug effects ; Radiation-Sensitizing Agents/*therapeutic use ; *Radiotherapy

Differentiated thyroid cancer can be effectively treated with high-dose 131I and the other head and neck cancer can also be effectively treated with extra-radiotherapy, but these treatments often result in a reduction in salivary gland function, causing xerostomia. Collectively, these effects can lead to severe secondary complications, including difficulty in speaking and swallowing, decreasing appetite even affecting nutrition and sleep. Amifostine, an analog of cysteamine, is a phosphorlyated aminothiol prodrug and its active metabolite, WR-1065 etc, can selectively protect normal tissues from the cytotoxic effects of drugs and/or radiation while preserve antitumor effects. Many studies have demonstrated that amifostine protects normal tissues from both acute and late extra-radiation damage without protecting the tumor. It has been approved by FDA to be used for protecting the salivary gland from xerostomia caused by radiotherapy. It has also show protecting effects on intra-radiotherapy, but there are many problems waiting for study.
Amifostine ; adverse effects ; therapeutic use ; Animals ; Clinical Trials as Topic ; Clinical Trials, Phase II as Topic ; Clinical Trials, Phase III as Topic ; Cytoprotection ; Head and Neck Neoplasms ; drug therapy ; radiotherapy ; Humans ; Rabbits ; Radiation Injuries ; prevention & control ; Radiation-Protective Agents ; pharmacology