Zietman, A.L. Journal of Clinical Oncology. July 10, 2016 vol. 34 no. 20 2323-2324
Why is radiation therapy not simply given in one large dose? This is a question that patients often ask of their radiation oncologists. The answer is simple: it could be, but such a dose would be equally damaging to the cancer and to the normal tissues within the radiation field. It would, essentially, be ablative, and this is an outcome that can easily be achieved by many other methods of energy delivery, not to mention surgery. In the early twentieth century, the pioneers of radiation therapy discovered empirically that fractionating the radiation—delivering it in multiple smaller doses to a higher total dose—not only preserved the power of the treatment to eradicate the tumor, but did so while better maintaining the integrity of the nearby normal tissues. Our increased understanding of radiation biology has given a scientific rationale to support fractionation, and radiation therapy became the cornerstone of the nonablative, organ-preserving strategies that we so commonly use today in breast, head and neck, and, of course, prostate cancer. Over the decades, small, daily fractions of 1.8 Gy to 2.0 Gy were recognized as safe, and these doses became customary throughout much of the world. Treatment courses are currently protracted out to ≤ 8 weeks, a time frame that is certainly inconvenient for many but a small price for a patient to pay for a treatment whose legacy may last a lifetime.
Read the full article here