Radiation Recall Phenomena in Cancer Treatments

Radiation recall phenomena encompass acute inflammatory responses occurring in tissues that were previously subjected to ionising radiation, triggered by the subsequent administration of certain systemic agents. These reactions can present in diverse organs—most commonly skin and lung—and range from mild erythema to severe pneumonitis. The interval between radiotherapy and recall may span days to years, underscoring the complex interplay between radiation-induced tissue alterations and drug-mediated immune or vascular effects. Clinically, radiation recall dermatitis manifests as confluent erythema, oedema and desquamation confined to the irradiated field, while radiation recall pneumonitis presents with cough, dyspnoea and radiographic opacities localised to prior radiation portals. A wide variety of antineoplastic drugs, including cytotoxics, targeted agents and immune checkpoint inhibitors, have been implicated, and rare reports now suggest vaccines as possible triggers. Although the precise mechanisms remain poorly defined, prevailing theories invoke upregulated cytokine release, endothelial damage and aberrant immune cell recruitment. Management rests on early recognition, withdrawal or modification of the inciting agent and initiation of corticosteroids or other supportive measures to prevent treatment delays and preserve patient quality of life.

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Radiation Recall Phenomena in Cancer Treatments publication trend

The graph below shows the total number of articles in radiation recall phenomena in cancer treatments across all publications each year (not limited to Nature Index journals).

Technical terms

Radiation recall reaction: An acute inflammatory response in a previously irradiated region following administration of a triggering systemic agent.

Radiation recall pneumonitis: Localised inflammatory lung injury confined to prior radiation fields that occurs after exposure to a recall-inducing drug or agent.

Radiation recall dermatitis: Re-emergence of skin inflammation—such as erythema and desquamation—in previously irradiated skin upon re-exposure to a triggering systemic therapy.

Immune checkpoint inhibitor: A class of anticancer therapeutics that block regulatory pathways in T cells to enhance host antitumour immune responses.

References

1. Radiation Recall Pneumonitis: A Rare Syndrome That Should Be Recognized. Cancers (2022).
2. Radiation Recall Pneumonitis Induced by Sintilimab: A Case Report and Literature Review. Frontiers in Immunology (2022).
3. Radiation recall dermatitis following letrozole administration in patient with a remote history of radiation therapy. npj Breast Cancer (2021).