Radiation oncology

ALSO KNOWN AS: Radiotherapy oncology

DEFINITION: Radiation oncology is the treatment of cancers using radiation, including therapeutic high-dose, high-energy forms of ionizing radiation, to shrink tumors and kill cancer cells. As one of the four major approaches to cancer treatment (surgery, chemotherapy, and biological therapy), radiation oncology is at the forefront of cancer treatment and research.

Subspecialties: Clinical radiation therapy, radiation and cancer biology, radiation physics

Cancers treated: Many cancers, including brain, head and neck, lung, breast, prostate, skin, eye, thyroid, rectum, cervical, and uterine cancer, as well as lymphomas and sarcomas.

Training and certification: The structure of accredited radiation oncology programs and residencies varies. In North America, most radiation oncologists have completed a radiation oncology residency in a program approved by the Accreditation Council for Graduate Medical Education (ACGME), the American Board of Radiology (ABR), or the Royal College of Physicians and Surgeons of Canada.

Radiation oncologists must possess a broad and deep command of cancer biology and imaging technology. They study the etiology of cancer; its evaluation, diagnosis, and treatment in a clinical setting; the ways radiation interacts with various cancers at all levels, from molecular to multicellular; the physics of radiotherapeutic technologies and associated machines such as linear accelerators and hyperthermia devices; techniques such as interstitial brachytherapy, intraoperative radiotherapy, and stereotactic radiosurgery; and a host of other disciplines associated with radiation therapy, such as nuclear medicine, oncology, diagnostic radiology, and surgical pathology.

During postdoctoral training, students may elect to focus on research, such as radiation biology, integrating advanced technologies and radiation physics with clinical research, or clinical practice. Most residencies in clinical radiation oncology require at least three, more often four, years to complete, usually following a first postgraduate year (PGY-1) of the surgical, medical, or flexible internship.

After receiving their primary certification, radiation oncologists must renew it every several years, depending on their subspecialties. For example, the American Board of Radiology requires its diplomates to satisfy its maintenance of certification (MOC) program to maintain their primary certification.

Services and procedures performed: All radiation oncologists participate in their patients' evaluation, staging, treatment, and therapy. They oversee the patient’s radiation oncology team, ensuring the precision and accuracy of radiation treatment, and they work with physicians treating the patient’s cancer in other ways. Throughout radiation therapy, radiation oncologists are responsible for monitoring the patient’s progress, side effects, and treatment to meet two goals—effectively halting the spread or reducing the size of cancer while considering the patient’s comfort. Balancing these objectives is essential to achieving the best outcome.

Radiation oncologists head a team of medical professionals who design and deliver the patient’s radiation treatments together. In concert with the patient’s primary oncologist, the radiation oncologist learns about the specifics of the patient’s cancer to determine the role radiation therapy will play in its treatment, then meets with the patient to evaluate their probable response to radiation therapy. Along with a radiation physicist and a dosimetrist, the radiation oncologist will design the treatment plan, which involves simulations, immobilization devices, calculating radiation dosages, and conducting periodic checks to confirm accurate treatment delivery.

The types of procedures radiation oncologists design and perform with the radiology team fall into two major categories. In the various forms of external beam radiation, the most common type of radiotherapy, the radiation oncologist uses a machine similar to an X-ray machine to direct high-energy X and gamma rays to the specific area of the body where the tumor resides. Treatments are given daily, usually for one to eight weeks and sometimes more than once a day, depending on the tumor and its aggressiveness.

Brachytherapy, also known as internal, implant, interstitial, or intracavitary radiation therapy, is the other main form of radiotherapy. The radiation oncologist implants a small amount of a radioactive substance in the body near the tumor in capsules called needles or seeds while the patient is under general anesthesia. Among the radioactive materials used are cesium, iridium, iodine, phosphorus, and palladium. This procedure often treats cancer in the cervix, prostate, eye, head, or neck.

Other procedures include electron therapy, including total skin treatment; radioimmunotherapy, in which monoclonal antibodies deliver the radiation by binding to the tumor cells; proton beam therapy, which uses protons to deliver higher doses of radiation to tumors than can be accomplished using conventional X and gamma radiation; neutron therapy, which can work in oxygen-free environments, such as the depths of a large tumor, to deliver radiation to cancers that other forms cannot treat; and stereotactic radiosurgery, such as the Gamma Knife, used to treat head and neck cancers by delivering a very high dose of radiation targeted directly at a tumor and sparing surrounding, healthy tissue.

Finally, radiation oncologists offer palliative treatment for those whose outcome is not expected to be survival but whose pain can be ameliorated by halting the growth of a tumor or shrinking its size.

Related specialties and subspecialties: Many radiotherapy subspecialists work with the radiation oncologist. While radiation oncologists oversee the care and integrate it with that of surgeons, chemotherapy oncologists, and other physicians, others on the radiology team often carry out the day-to-day application of radiotherapy to the patient’s tumor members.

First, radiation physicists, certified by the American Board of Radiology or the American Board of Medical Physics, work directly with the radiation oncologist, oversee dosimetrists, develop quality-control programs for procedures, and perform safety tests on equipment. Their education usually consists of four years of college, two to four years of graduate school, and one or two years of clinical physics training.

Radiation therapists, under the supervision of radiation oncologists, administer the daily treatments, keep records, and check the performance of machines. They typically have two to four years of college education and have been certified by the American Registry of Radiologic Technologists. Many states also require licensing for radiation therapists.

Dosimetrists calculate radiation dosages and durations to damage the tumor while preserving normal tissue. Because of the complexity of determining treatment dosages, dosimetrists often start as radiation therapists, recieve additional training, and advance to dosimetry. Some intensive dosimetry programs last one to two years. Dosimetrists are certified by the Medical Dosimetrist Certification Board.

Radiation oncology nurses are charged with caring for radiation patients from before the beginning of treatment through its completion. They are the patient’s first line of communication regarding what to expect during the procedure and how to identify and evaluate side effects. All radiation oncology nurses are registered nurses. Most are accredited in oncology nursing, requiring a master’s degree.

Bibliography

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Chandra, Ravi A., et al. Career Development in Academic Radiation Oncology. Springer, 2021. 

Halperin, Edward C., et al. Perez and Brady's Principles and Practice of Radiation Oncology. 7th ed., Lippincott, 2019.

Holmes, Jason, et al. "Evaluating Large Language Models on a Highly-specialized Topic, Radiation Oncology Physics." Frontiers in Oncology, vol. 13, 2023. doi.org/10.3389/fonc.2023.1219326.

Hristov, Boris, et al. Radiation Oncology: A Question-Based Review. 3rd ed., Wolters, 2019.

"Radiation Therapy to Treat Cancer." National Cancer Institute, 8 Jan. 2019, www.cancer.gov/about-cancer/treatment/types/radiation-therapy. Accessed 20 July 2024.

"Radiation Oncology." Mayo Clinic, 7 May 2024, www.mayoclinic.org/departments-centers/radiation-oncology/sections/overview/ovc-20188591. Accessed 20 July 2024.

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"What Is Radiation Oncology?" WebMD, 30 Aug. 2022, www.webmd.com/cancer/radiation-oncology. Accessed 20 July 2024.