RadiotherapyEdit

Radiotherapy, or radiotherapy, is a foundational modality in cancer care that uses high-energy radiation to damage the DNA of cells, with the aim of killing malignant cells or halting their growth. Because cancer cells often divide more rapidly and are less able to repair radiation-induced damage than surrounding normal tissues, radiotherapy can achieve tumor control or palliation with a favorable balance of benefits and risks when applied with careful planning. Treatments can be curative for certain cancers, palliative to relieve symptoms in others, or employed in combination with surgery and systemic therapies such as chemotherapy or immunotherapy. Advances in imaging, treatment planning, and delivery have improved precision, reducing exposure to healthy tissue and expanding the range of cancers that can be treated effectively. RadiotherapyExternal beam radiotherapyBrachytherapy.

Radiotherapy is delivered through a few broadly defined approaches, each with its own strengths and limitations. External beam radiotherapy (EBRT) uses linear accelerators to project high-energy photons or particles at the tumor from outside the body, with modern planning technologies shaping the dose to conform to the target while sparing normal tissue. Internal or brachytherapy places a radiation source inside or very near the tumor, delivering high doses over short distances and times. A range of specialized techniques—such as intensity-modulated radiotherapy (IMRT), image-guided radiotherapy (IGRT), and stereotactic body radiotherapy (SBRT)—increase precision and allow complex dose distributions. Proton therapy and other particle therapies, leveraging the physical properties of protons or heavier ions, offer potential advantages in certain settings but remain areas of active discussion regarding cost and selective indications. IMRTVMATSBRTImage-guided radiotherapyProton therapy.

History and context help explain how radiotherapy fits into modern medicine. Early use of radiation began in the late 19th and early 20th centuries, with gradual improvements in equipment, dosing, and understanding of tissue response. The development of fractionation—delivering the total dose in multiple smaller fractions over several weeks—proved crucial for balancing tumor control with the protection of normal tissues. Over the decades, radiotherapy has evolved from large, crude devices to highly precise systems guided by computerized planning, high-resolution imaging, and real-time positioning. For patients and clinicians, radiotherapy sits alongside surgical and medical oncology as a standard treatment modality in many cancers, with ongoing research aimed at expanding indications and improving outcomes. Radiation therapyFractionation.

Techniques and planning are central to radiotherapy. Planning begins with imaging studies (often CT, sometimes MRI or PET) to delineate the tumor and nearby organs at risk. The planned dose—measured in gray (Gy)—is distributed across the treatment fields so that the tumor receives an adequate total dose while minimizing exposure to healthy tissue. Modern systems use advanced delivery methods, such as IMRT or volumetric modulated arc therapy (VMAT), to sculpt dose distributions in three dimensions. Image guidance ensures the patient’s position and anatomy match the planning data at daily treatment, enabling tighter margins and reduced toxicity. For certain cancers, brachytherapy delivers high doses locally and has a long track record of effectiveness in diseases like cervical cancer and prostate cancer. Radiation therapy planningIMRTBrachytherapy.

Clinical use and outcomes reflect a balance of effectiveness, toxicity, and patient preferences. In many solid tumors, radiotherapy can achieve local control and long-term survival, particularly when integrated with surgery or systemic therapy. It is especially well established in cancers of the head and neck, cervix, endometrium, prostate, lung (as a definitive or adjunctive treatment), and breast, among others. In palliative settings, radiotherapy can rapidly relieve pain, reduce obstruction, or improve quality of life for patients with advanced disease. Across indications, the choice of modality, dose, and fractionation is guided by tumor biology, anatomy, prior treatments, and patient values. Prostate cancerCervical cancerHead and neck cancerBreast cancerLung cancer.

Controversies and debates surrounding radiotherapy often center on cost, access, and value. From a policy and practice perspective, a central question is how to allocate resources efficiently while expanding patient choice. High-cost technologies, such as proton therapy, offer theoretical advantages for certain tumors or pediatric cases but require careful patient selection and robust comparative data to justify their higher price tag relative to conventional photon-based approaches. Critics argue that the most cost-effective care emphasizes proven protocols, guideline-concordant use, and timely access, while supporters contend that selective investment in advanced technologies can drive better outcomes for specific patients and tumor types. The core principle in this debate is aligning clinical benefit with real-world value, avoiding both underuse and overtreatment. Proton therapyCost-effectivenessQuality-adjusted life year.

In the broader ethics and regulation conversation, safety and equity are paramount. Radiotherapy is governed by radiation protection standards intended to minimize unnecessary exposure to healthy tissue, guided by the ALARA principle (As Low As Reasonably Achievable). Regulators and professional bodies—such as national health authorities, radiation safety commissions, and specialty associations like the American Society for Radiation Oncology (ASTRO) in the United States and the European Society for Radiotherapy and Oncology (ESTRO)—define practice guidelines, credentialing, and quality assurance programs. Safety considerations extend to patient care pathways, staff training, and the maintenance of equipment, ensuring that advances in technology do not outpace safeguards. ALARAASTROESTRO.

Economic aspects and access to radiotherapy vary widely across health systems. In many settings, radiotherapy is delivered in publicly funded hospitals, private clinics, or hybrid arrangements, with reimbursement levels shaping availability and timeliness. The high upfront cost of modern radiotherapy units, maintenance, and facility requirements can limit access in rural or low-resource regions, raising concerns about disparities. Policymakers and health economists emphasize outcomes research, cost-effectiveness analyses, and strategic investment to maximize patient value while encouraging innovation. This includes considering when shorter, hypofractionated schedules can achieve comparable outcomes with fewer visits, thereby improving patient convenience and reducing system burdens. Healthcare economicsHypofractionationGlobal health.

Future directions in radiotherapy combine precision with personalization. Ongoing research explores adaptive radiotherapy, where treatment is adjusted in response to anatomical changes during therapy; MR-Linac platforms integrate magnetic resonance imaging with linear accelerators for real-time guidance. Combinations with immunotherapy and targeted agents hold promise for synergistic tumor control, while ongoing trials assess optimal dosing, sequencing, and toxicity management. The goal is to extend the reach of radiotherapy to more patients, improve outcomes, and reduce side effects, all within a framework that rewards value, safety, and patient-centered care. MR-LinacAdaptive radiotherapyImmunotherapy.

See also - Proton therapy - Brachytherapy - IMRT - Stereotactic body radiotherapy - Image-guided radiotherapy - Fractionation - Radiation safety - ASTRO - ESTRO - Cancer therapy