Proton Beam Therapy: How Protons are Revolutionizing Cancer Treatment PDF
Preview Proton Beam Therapy: How Protons are Revolutionizing Cancer Treatment
Proton Beam Therapy Santosh Yajnik Proton Beam Therapy How Protons are Revolutionizing Cancer Treatment Santosh Yajnik, MD Radiation Oncologist Radiation Oncology Consultants, Ltd. Chicago , IL, USA ISBN 978-1-4614-5297-3 ISBN 978-1-4614-5298-0 (eBook) DOI 10.1007/978-1-4614-5298-0 Springer New York Heidelberg Dordrecht London Library of Congress Control Number: 2012944982 © Springer Science+Business Media New York 2013 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, speci fi cally the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on micro fi lms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied speci fi cally for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is permitted only under the provisions of the Copyright Law of the Publisher’s location, in its current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a speci fi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface As a physician who has treated thousands of patients with cancer, I am aware of two obvious truths about my specialty of radiation oncology. First, if you give a high enough dose of radiation to a tumor, it will be destroyed. As an obvious example, an atomic bomb sized dose of radiation will destroy even the most aggressive tumor. But, alas, what would become of our patient? This brings to bear the second obvious truth about my specialty. Too much radiation kills healthy tissue. Thus, the ideal treatment should deliver a lethal dose to the area of cancer while sparing the sur- rounding normal tissues from the harmful effects of radiation. In other words, the bene fi cial effects of radiation therapy occur when a lethal dose of radiation is depos- ited in the area of cancer and the harmful effects of radiation therapy occur when healthy tissue is inadvertently irradiated while trying to treat the cancer. Radiation therapy is a mainstay of treatment for cancer. In fact, more than half of the patients diagnosed with cancer in the USA receive radiation therapy. Most radia- tion therapy is delivered via electron accelerators. There are thousands of electron accelerators in the USA. They speed up electrons to a high velocity. The electrons can be made to strike a tungsten target within the head of the accelerator to create a beam of photons (or “X-rays”). These X-ray beams are then directed at the site of cancer. Photons have no charge or mass and can be regarded as small packets of energy. Photons deposit their energy along the entire path that they travel through the body. Therefore, a beam of X-rays irradiates not only the area of cancer but also the healthy tissue that the beam encounters on its way towards the tumor and beyond the tumor. X-rays used for treating cancer usually do not stop within the body. X-rays travel right through you. On the other hand, proton beam therapy is delivered by larger, much more expen- sive accelerators called cyclotrons and synchrotrons. There are only ten functioning proton beam therapy centers in the USA, but many more are being constructed or planned. Protons have a positive charge and mass. Because of their charge and mass, protons behave very differently than X-rays within the body. A proton beam directed at a tumor travels in a straight trajectory towards its target, gives off most of its energy at a de fi ned depth called the Bragg peak, and then stops. While X-rays often deposit more energy within the healthy tissues of the body than within the cancer v vi Preface Fig. 1 The dose deposited as a function of depth within the body is shown for X-rays (photons) by the red line and protons by the b lue line . Note that the b lue line travels in a straight trajectory towards the tumor, has a spread out burst of energy that covers the tumor, and then stops. Note that the X-ray beam (r ed ) continues to travel past the tumor and delivers radiation to the healthy tissues both anterior and posterior to the tumor. The red color-wash represents the amount of excess healthy tissue within the body that is irradiated by X-rays but not irradiated by proton beam ther- apy. Provided by Procure Treatment Centers, Inc. with permission itself, protons deposit most of their cancer killing energy within the area of tumor (see Fig. 1 ). Compared with X-rays, proton beam therapy has the ability to improve cure rates by increasing the dose delivered to the tumor and simultaneously reduce side effects by decreasing the dose to surrounding healthy tissue. Tumors of the base of the skull offer an excellent example of the bene fi ts of pro- ton beam therapy compared with X-rays. A tumor arising in or extending to the base of the skull in a child can be a devastating diagnosis. Such tumors are in close prox- imity to critical structures such as the brainstem, optic chiasm, cranial nerves, and critical blood supply. The tumor may present itself when symptoms such as blind- ness, facial droop, headache, or numbness appear. While surgery is often attempted for these tumors, complete surgical removal is often unachievable. The challenges of irradiating such a critical part of the body are magni fi ed in a child compared with an adult because the developing tissue of the child is much more susceptible to the harmful effects of radiation. The potential for devastating long-term cognitive, behavioral, and cosmetic defects from treatment is high. Conventional X-ray treat- ments have proven to show inferior results when compared with proton beam ther- apy for such tumors. A study done at the Harvard Cyclotron Laboratory and the Loma Linda University Medical Center demonstrated 5-year local control in 72% of children with base of skull tumors treated with proton beam therapy [1]. Proton Preface vii Fig. 2 Images of a skull base tumor treatment plan with red depicting the target and blue and blue–green colors depicting the radiation dose deposited in the target and surrounding tissue. The axial and sagittal images on the l eft panel show the dose deposited by proton beam therapy. The panel in the center shows the dose deposited with photons (X-rays). The panel on the right shows in red color-wash the excess dose that is deposited by X-rays compared with proton beam therapy. Provided by Procure Treatment Centers, Inc. with permission beam therapy controlled these devastating tumors in the majority of children while shielding precious normal tissues from the harmful effects of radiation (see Fig. 2 ). The bene fi ts of proton beam therapy in delivering a lethal hit to the target while sparing surrounding normal tissues from radiation are becoming applicable to an increasing number of patients and a growing list of conditions. In this book, I will guide the reader through the existing evidence supporting proton beam therapy for pediatric conditions, prostate cancer, lung cancer, mediastinal tumors, central ner- vous system conditions, skull base tumors, conditions of the eye, and sarcomas. This book offers, in an easy-to-read format, an introduction to some of the common indications for proton beam therapy. In writing this book, I have drawn upon three aspects of my background. First, as a radiation oncologist who is on staff at the CDH Proton Center, I utilize proton beam therapy to treat patients with a variety of conditions. Second, I am a partici- pant in the research efforts of the Proton Collaborative Group and conduct clinical research using proton beam therapy. Finally, I am part of a team of physicians, engi- neers, physicists, and entrepreneurs who came together to conceptualize, fi nance, build, and operate the CDH Proton Center, the ninth proton beam therapy center to treat patients in the USA ( Fig. 3 ). viii Preface Fig. 3 A photograph of the CDH Proton Center located in the Chicago suburb of Warrenville, Illinois, where we have been treating patients since October of 2010. Provided by Procure Treatment Centers, Inc. with permission I would like to thank my patients for teaching me some of life’s most important lessons. I would like to thank my colleagues in medicine, medical physics, and nurs- ing for the important work that you do. I would like to thank my family for their love and support. I greatly appreciate the opportunity to write this book and will donate all my author’s royalties to the Procure Cancer Foundation, an organization that provides fi nancial support to patients undergoing proton beam therapy. Reference 1. Hug EB, Sweeney RA, Nurre PM, Holloway KC, Slater JD, Munzenrider JE. Proton radio- therapy in management of pediatric base of skull tumors. Int J Radiat Oncol Biol Phys. 2002;52(4):1017–24 . Contents 1 An Introduction to Proton Beam Therapy ............................................ 1 Rationale for Proton Beam Therapy .......................................................... 1 Early Therapeutic Uses of Proton Beam Therapy ..................................... 3 Selected Current Clinical Applications of Proton Beam Therapy ............. 4 Discussion and Future Directions .............................................................. 8 Relative Biologic Effectiveness ............................................................. 8 Secondary Malignancy Risk .................................................................. 9 Cost Considerations ............................................................................... 9 Conclusion ................................................................................................. 10 References .................................................................................................. 10 2 Comparative Treatment Plans ................................................................ 13 Comparative Treatment Plans .................................................................... 13 Pediatric Craniospinal Irradiation .............................................................. 14 Brain Tumors ............................................................................................. 16 Prostate Cancer .......................................................................................... 19 Liver ........................................................................................................... 23 Spine .......................................................................................................... 25 Mediastinal Tumors ................................................................................... 25 Discussion and Future Direction ................................................................ 28 References .................................................................................................. 28 3 Proton Therapy for Pediatric Conditions .............................................. 31 Proton Therapy for Pediatric Conditions ................................................... 31 Pediatric Cancer ..................................................................................... 31 Simulation and Treatment Planning ........................................................... 32 Dosimetric Considerations ......................................................................... 32 Selected Conditions and Trials .................................................................. 34 Medulloblastoma .................................................................................... 34 Other Central Nervous System Conditions ................................................ 35 Noncentral Nervous System Pediatric Conditions ..................................... 37 ix
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