Radiation therapy (RT) is an integral treatment modality for several malignancies. The ionizing effects of radiation damage the DNA leading to cell death (6). Although aimed at malignant cells, normal cells are also susceptible to the damaging effects of RT. Side effects of RT is dependent upon tissue sensitivity and proximity to the radiation source, cumulative radiation dose, and concomitant chemotherapy. Adverse effects of RT stems from acute tissue swelling, secondary malignancies, and the long-term sequelae of tissue fibrosis (7–9). Neck radiation is known to cause lymphedema and tissue fibrosis in the long term (10). The likelihood of radiation-induced esophageal injuries is influenced by the radiation modality, total radiation dose to the esophagus, concurrent chemotherapy, and pre-existing esophageal diseases (11–15). Radiation doses in excess of 40–50 Gray (Gy) correlate with esophagitis risk (16). Radiation-induced esophageal injuries are commonly graded using the Radiation Therapy Oncology Group (RTOG) and the European Organization for Research and Treatment of Cancer (EORTC) toxicity grading scale (17). In patients with non-small cell lung cancer (NSCLC) acute severe esophageal injuries had a reported incidence of 46% in one study (18) while only 3% had RTOG grade 3 late toxicity in another report (13). Esophageal strictures have been reported in pediatric patients, 10–15 years of age, after chest radiation for Hodgkin lymphoma (19, 20). The incidence of esophageal strictures in adults after radiotherapy for head and neck cancer was 3.3% in one report (21). NSCLC radiotherapy is also associated with the development of esophageal strictures (22).
The incidence of esophageal adverse effects with breast cancer radiotherapy is less well-studied. It is known, however, that there is an increased risk of esophageal cancer as second primary cancer in breast cancer survivors, and that risk is incremental with increasing radiation dose (23–25). Radiation doses to the esophagus are highest if supraclavicular and/or internal mammary lymph nodes were included in the treatment fields with a median dose of 25–38 Gy. Tangential fields resulted in significantly lower doses to the esophagus (less than 2 Gy) (24, 26).
The aforementioned late esophageal sequelae of radiation therapy pose a concern for higher risk of injuries with esophageal instrumentation, especially those done without direct visualization. Prior chest radiation is considered a relative contraindication to transesophageal echocardiography (5) however, the evidence supporting such recommendation is limited to case reports (27). In a meta-analysis of 22 studies, all perforations occurred in patients without perceivable risk factors (28). In another large single-center study, including 10,000 patients, 3 perforations occurred, none of which had risk factors, including chest radiation (29). Nevertheless, the safety of TEE in patients with prior chest radiation has never been systematically studied.
In our study 49 TEE examinations, in 31 patients, were performed successfully with no reported complications in a 30 day follow up period. The most frequent indication for TEE was intraoperative for cardiac surgeries (Fig. 4). The median radiation dose was relatively high at 54 Gy (Fig. 3). The study included 16 patients with combined chemoradiation therapy, which infers a higher risk of esophageal adverse effects, none of which suffered significant complications.
The limitations of our study include a small sample size and possible selection bias, where only 3 patients (9.6%) had reported dysphagia/odynophagia. It is possible that patients with significant dysphagia were denied the procedure and can’t be accounted for in our conclusion. Another limitation of the study is the inclusion of 12 patients with lymph node-negative breast cancer who may not have received a significant radiation dose to the esophagus given the use of tangential fields and the exclusion of regional lymphatics from the radiation field (24, 26).