Objective To explore changes of blood pressure and thyroid hormones and their correlations after radiotherapy in patients with cervical and upper thoracic (CUT) esophageal cancer.

Methods A retrospective analysis was conducted on patients with esophageal cancer who received concurrent chemoradiotherapy in the Department of Radiation Oncology, Zhongshan Hospital, Fudan University, from January 2019 to September 2021. According to tumor location, patients were divided into the CUT group and the middle and lower thoracic (MLT) group. Systolic blood pressure (SBP), diastolic blood pressure (DBP), serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid stimulating hormone (TSH) levels were compared between the two groups before radiotherapy and 7.5 months after radiotherapy. Pearson’s test was used to assess the correlation between changes in thyroid hormones and changes in blood pressure.

Results A total of 112 patients were enrolled, 55 cases in the CUT group and 57 cases in the MLT group. Compared with before radiotherapy, SBP and DBP decreased (P＜0.001), serum FT3 and FT4 levels decreased (P＜0.001), and TSH levels increased (P＜0.001) in the CUT group 7.5 months after radiotherapy; changes in blood pressure and thyroid hormones in the MLT group were not statistically significant. Pearson’s test showed that changes in FT3 and FT4 were positively correlated with changes in SBP (FT3: r＝0.430, P＝0.001; FT4: r＝0.667, P＜0.001) and DBP (FT3: r＝0.370, P＝0.005; FT4: r＝0.469, P＜0.001).

Conclusions Radiotherapy in patients with CUT esophageal cancer can cause a decrease in blood pressure, which may be related to changes in thyroid hormones caused by radiation-induced thyroid injury.