Hypofractionated radiation therapy in the modern era

Choice of the appropriate fractionation schedule in a modern radiation therapy department requires clear understanding of the radiobiologic principles that govern the tumor or normal tissue responses to radiation therapy as well as the goals and expected outcomes for the individual patient. Although the majority of patients will be most appropriately treated with conventional fractionated radiation therapy (dose per fraction less than 225 cGy), there may still be a role hypofractionated treatment for selected patients. Currently it is not feasible to taylor the fractionation regiment to the patient's individual and specific tumor cell survival characteristics. Thus, in malignant melanoma, despite the demonstration of "wide shoulders" on the cell survival curve, it has not been demonstrated clinically that large doses per fraction are clearly advantageous. Many patients may be well palliated with hypofractionated regimens. However, this requires the physicians to carefully select their patients and where resources allow, many patients will be better palliated with higher total doses and lower doses per fraction. This is especially true if they survive for longer than one year. Lastly, new technology that allows for the delivery of highly conformal radiation therapy needs further study relative to the optimal fractionation in its application.