Radiation recall syndrome in a patient with breast cancer, after introduction of everolimus

Radiation recall reactions: An oncologic enigma

Radiation recall reactions (RRR) are uncommon but are a well-known phenomenon to oncologists. Tissue damage in a prior irradiation portal is 'recalled' after the administration of a drug, historically cytotoxics, or more recently, targeted or immunotherapeutic agents. Even COVID-19 vaccines are a reported cause. RRR are enigmatic in that their cause is unknown, but they generally have the histopathological and clinical features of acute or chronic inflammation. They can occur in a variety of tissues, the commonest being skin, which accounts for two-thirds of reported cases. They are generally relatively mild and self-limiting once the trigger drug is stopped, although severe cases with tissue necrosis have occurred. Rechallenge with drug does not necessarily cause reactivation of the reaction. Symptomatic treatment with steroids and antihistamines are usually effective, but their impact on the clinical course is unclear. Various hypotheses have been proposed as to the mechanism of RRR; a non-immune fixed drug reaction-like condition, dysregulated release of reactive oxygen species, abnormalities of tissue vasculature and impaired DNA repair. All could lead to a characteristic inflammatory microenvironment, resulting in dysfunction of tissue stem cells, keratinocyte necrosis and dermal abnormalities. Alternatively or in addition, low levels of inflammatory tissue cytokines induced by previous irradiation might be further upregulated by drug exposure. Most information in this review refers to data derived from cutaneous RRR, since they are the most common form reported.

“Radiation Recall Phenomenon” with Novel Cytotoxic Agents: An Emerging Trend in the Last Decade

Radiation recall phenomenon (RRP) is an acute inflammatory reaction manifested in the previously irradiated tissues after the administration of various pharmacologic compounds. While skin manifestations are the most common clinical features, patients may also present with visceral recall events including pneumonitis, hematuria, myopathy, and mucositis if any particular organ was exposed to the prior radiation portals. This article has reviewed the published case reports, case series, abstracts, and poster presentations in the past 10 years in any language on RRP caused by various novel cytotoxic drugs including immunotherapies, molecularly targeted agents, and unconventional chemotherapies. We retrieved the data through the literature search of MEDLINE and PubMed using the keywords “radiation,” “recall,” “targeted therapy,” and “immunotherapy,” and references identified in retrieved articles were also used for further search of the literature. With the increasing use of unconventional, novel cytotoxic agents and targeted molecules, concurrent or sequentially with radiation, we expect more incidences of RRP in future that may present with either dermatological or visceral recall reactions.

Concurrent Radiation and Modern Systemic Therapies for Breast Cancer: An Ever-Expanding Frontier

Radiotherapy is a critical tool for reducing locoregional recurrence, extending survival, and palliating symptoms in patients with breast cancer. With an ever-expanding armamentarium of systemic agents available, and an increasing trend toward the use of hypofractionated radiation regimens, it can be difficult to determine the safety of concurrent therapy. In particular, new targeted agents in both the adjuvant and metastatic setting have limited prospective or long-term data demonstrating safety when delivered concurrently with radiotherapy. Other systemic agents, including chemotherapy and endocrine therapy, are also important components of the overall treatment strategy for localized and metastatic breast cancer, and are often delivered concurrently with radiation in certain clinical scenarios. This review explores the safety, efficacy, and pitfalls of delivering radiation in conjunction with systemic therapies for breast cancer.