Recent developments in radiation oncology-integrating radiation physics and molecular radiobiology advances into clinical radiotherapy practice and beyond

Significant developments in radiation oncology have taken place in recent years as a result of advances in radiation physics and molecular radiobiology. From the conventional 2-dimensional (2D) radiotherapy to 3-dimensional (3D) conformal radiotherapy, we have now entered the era of intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT). IMRT/IGRT allows conformal treatment of tumor and conformal avoidance of normal tissues leading to possible improvement of tumor control and decrease in treatment-related toxicity. Frameless stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) have now become a reality, offering more treatment options in radiation oncology. With technological advances in image guidance, brachytherapy especially in early stage prostate cancer has progressed and shown excellent long-term outcome data. Charged particle therapy including proton therapy is a promising area for new development. Combining radiotherapy with the more traditional chemotherapy and hormonal therapy to novel targeted therapy and gene therapy is aimed to overcome radio-resistance, improve the radio-therapeutic index and provide better loco-regional and systemic control of cancer. A recent randomized trial in head and neck cancer has shown improved survival data when comparing combined radiotherapy and targeted therapy with radiotherapy alone. Recent advances in functional or molecular imaging offer new opportunity to improve targeting of tumor, for example, hypoxic region, and possibly to perform radiation dose painting with IMRT. Integrating PET/CT in radiotherapy has shown promise in assisting target delineation during treatment planning and assessing radiation treatment response. Cancer stem cell, gene expression profiling and nanotechnology with the implications on radio-resistance are new exciting areas requiring more research in future as we move toward personalized medicine.