Elsevier

The Lancet

Volume 398, Issue 10295, 10–16 July 2021, Pages 171-184
The Lancet

Review
Contemporary radiotherapy: present and future

https://doi.org/10.1016/S0140-6736(21)00233-6Get rights and content

Summary

Oncology care is increasingly a multidisciplinary endeavour, and radiation therapy continues to have a key role across the disease spectrum in nearly every cancer. However, the field of radiation oncology is still one of the most poorly understood of the cancer disciplines. In this Review, we attempt to summarise and contextualise developments within the field of radiation oncology for the non-radiation oncologist. We discuss advancements in treatment technologies and imaging, followed by an overview of the interplay with advancements in systemic therapy and surgical techniques. Finally, we review new frontiers in radiation oncology, including advances within the metastatic disease continuum, reirradiation, and emerging types of radiation therapy.

Introduction

Although the beginnings of modern radiotherapy can be traced back to the discovery of the x-ray in the late 1800s, the field of radiation oncology has had multiple renaissances since its formal inception six decades ago.1, 2 As imaging and treatment delivery techniques have improved, the applications of radiation oncology have expanded. Approximately half3, 4 of patients are estimated to receive radiotherapy at some point after a diagnosis of cancer, with indications spanning curative treatment to symptom palliation.

Close collaboration across oncological fields is crucial to improve treatment and ensure the optimal application of radiotherapy. There have been multiple advances in radiotherapy. For this Review, we aimed to provide a useful and pragmatic overview for non-radiation oncologists, with an emphasis on how technological enhancements have led to smaller treatment volumes, shorter treatment times, better outcomes, and decreased toxicity. We have focused on data from randomised trials, consensus guidelines, and promising emerging research that have transformed the field. We also look at the potential effect of current technologies and how they might shape the field during the coming decades.

Section snippets

New technology: evolving radiotherapy

Improvements in diagnostic imaging, treatment planning, and treatment delivery have enabled more accurate and precise treatment of diseased tissue and avoidance of healthy tissues. This has expanded the so-called therapeutic window, the dose range in which tumours can be effectively treated and side-effects can be minimised.

The evolution of modern radiotherapy is shown in figure 1. Historically, radiotherapy was planned and delivered in two dimensions, with treatment fields based on bony

New imaging: improved target definition, quantification of response, and novel therapies

Improvements in diagnostic imaging have enabled more precise identification of both target volumes and healthy tissue in radiotherapy treatment planning. For example, improvements in MRI have allowed a more complete assessment of intracranial disease burden than before. Coupled with advances in radiotherapy planning, this enhanced assessment of intracranial disease has led to a shift in the management of brain metastases, from whole brain radiotherapy to targeted treatments with stereotactic

New biology: a changing role with systemic therapy

Developments in systemic therapy have also transformed the role of radiotherapy, enabling treatment with smaller radiotherapy fields, which has decreased the potential short-term and long-term side-effects of radiotherapy. One example of this decrease in side-effects has been in Hodgkin lymphoma. This highly radio-responsive disease was historically treated successfully with radiotherapy alone, with treatment of the primary tumour and draining nodal basins. Although patients, often diagnosed in

New surgical cooperation: evolving framework of care

With the increase of multimodality treatment use, outcomes for many cancer patients have improved; however, treatment intensification often comes with an effect on patients' quality of life. The need for treatment intensification to improve outcomes or de-intensification to improve quality of life differs between cancers. Substantial improvements in outcomes for breast, Hodgkin lymphoma, and head and neck cancer have resulted in exploring de-escalation of treatments. The balance and need of

Special example: stereotactic radiosurgery or SBRT

The development and increasing use of stereotactic radiosurgery and SBRT in multiple disease sites has ushered in a new era of radiotherapy. There is established data for SBRT in nearly every cancer subsite that radiation oncologists treat, with indications ranging from early-stage disease (eg, in lung cancer) to locally advanced disease (eg, unresectable pancreatic cancer) and metastatic disease. These techniques are particularly appealing given the short course of treatment and small volumes

Evolving indications: re-irradiation

Improved survival of patients with cancer has resulted in increased consultations for re-irradiation. In radiotherapy-naive patients, dose constraints and corresponding toxicity profiles are robust. For re-irradiation, there is a paucity of data, which limits determination of firm guidelines or dose constraints. Therefore, efforts to guide clinical decision making in re-irradiation and determination of cumulative tolerated doses are based on small series and consensus recommendations.114, 115

Costs and gains of new treatment advances

In the past decades, radiotherapy technology has rapidly evolved, and many new radiotherapy treatment options have become available in high-income countries. Although these advances often reduce toxicity and improve patient outcomes,15, 124 they also have an increased financial cost.125 Cost-effectiveness studies have attempted to objectively quantify the benefit of these treatments. For example, for paediatric patients who have medulloblastoma, proton beam therapy is associated with decreased

Future for radiation oncology

As discussed in this Review, advances in radiotherapy could lead to the use of personalised radiotherapy prescriptions, individualised treatment based on accurate response prediction, an increase in organ preservation, novel indications in non-oncological diseases, increased use of particle therapy, and even more robust and adaptable responses to immunomodulatory therapies than before. Technological advances in radiotherapy delivery will continue in the coming years. We have highlighted

Search strategy and selection criteria

References for this Review were identified through searches of PubMed and MEDLINE for articles, including high quality reviews, reports of practice changing, and randomised trial data, from Jan 1, 1980, to Dec 31, 2020, with search terms such as “radiotherapy”, “charged particle therapy”, “3D conformal radiotherapy”, “intensity-modulated radiotherapy”, and “randomized trial”. Emphasis was placed on articles less than 10 years old. We organised new developments into topical areas, which then

Declaration of interests

We declare no competing interests.

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