What is Involved-Field Radiation Therapy (IFRT)?

A patient undergoing a radiation treatment.
A patient undergoing a radiation treatment. Isa Foltin/Getty Images

Question: What is Involved-Field Radiation Therapy (IFRT)?

Involved-field radiation therapy (IFRT) is a term used for delivering radiation to only those areas of the body involved by lymphoma. For example, if lymphoma affects the left side of the neck, IFRT will deliver radiation to the entire left side of the neck. If lymphoma affects two areas like the neck and the armpits, radiation will be delivered to these two sites only.

Field Size for Radiation Therapy is Shrinking

This term is used in comparison with extended field radiation therapy, which delivers radiation to larger areas of the body, including regions not immediately involved by lymphoma. It was used for many years for lymphoma. However, the radiation also affects nearby areas and organs and patients had higher rates of secondary cancer in the part of the body exposed, especially breast cancer in women and lung cancer in men. They could also have damage to their heart, lung and thyroid function.

While a good survival rate for lymphoma was achieved, some patients would develop secondary cancers or have damage to their other critical organs.

Studies found similar effectiveness for radiating only the involved field rather than an extended area. The patients studied had the same rates of complete response, progression, relapse and deaths. But they also had fewer immediate side effects such as low blood counts, nausea, and change of taste.

Because of these advantages, there was widespread adoption of IRFT for radiation treatment in Hodgkin and Non-Hodgkin lymphoma. Here are some situations where IFRT became to be used:

  • Follicular lymphoma treatment– as the only treatment in stage I disease.
  • In any type of lymphoma when there is a residual mass after chemotherapy, or a small area of relapse after a period of remission with chemotherapy.

Most treatments with involved field radiation are completed in 4 to 5 weeks. The duration of treatment depends on the dose delivered. As IFRT is commonly given after chemotherapy, the dose is often based on how much disease remains after chemotherapy.

Adoption of Involved Site Radiation Therapy

However, even smaller areas of radiation are becoming more standard with involved site radiation therapy, aimed only at the lymph nodes that originally contained Hodgkin disease. This is replacing IFRT for Hodgkin disease in some clinical guidelines and institutions.

There is also involved nodal radiation therapy (INRT). Whereas IFRT irradiates a region of lymph nodes, INRT focuses only on the nodes that are enlarged after chemotherapy. It also compares favorably in trials with extended field and involved field radiation therapy.

The preferred treatment will continue to evolve so there is less damage to healthy tissues while still being effective against the lymphomas. The goal is to kill only the lymphoma cells without exposing other areas to radiation and its effects.

Discuss radiation therapy with your doctor to understand how and why different types of therapy may be used for your case.


Magdalena Witkowska, * Agata Majchrzak, and Piotr Smolewski. "The Role of Radiotherapy in Hodgkin's Lymphoma: What Has Been Achieved during the Last 50 Years?" Biomed Res Int. 2015; 2015: 485071.

Radiation therapy for Hodgkin disease, American Cancer Society, 02/09/2016.

Continue Reading