Influence of radiotherapy on blood pressure in patients with cervical and upper thoracic esophageal cancer

Abstract Background An interesting clinical phenomenon occures frequently in our work, which indicates that blood pressure could return to normal in some hypertension patients with cervical & upper thoracic esophageal cancer undergoing radiotherapy. We speculated that this may be related to thyroid gland damage by radiotherapy.Methods We retrospectively analyzed pre- and post-radiotherapy (RT, 1.5months, 4.5months and 7.5months) systolic blood pressure (SBP) and diastolic blood pressure (DBP) for a cohort of esophageal cancer patients. At 7.5 months post-RT, serum free triiodothyronine (FT3), free tetraiodothyronine (FT4) and thyroid-stimulating hormone (TSH) concentrations were also measured to evaluate the changes of thyroid hormones (THs) and its correaltion with changes of blood pressure. To confirm the influence of radiation on thyroid, patients were divided into cervical & upper thoracic group (C&U, n=55) and middle & lower thoracic group (M&L, n=57). Results In the C&U group, the decreases (±SD) in SBP and DBP, respectively, were 5.51 mmHg (±1.83, P=0.003) and 3.62 mmHg (±1.38, P=0.002) at 1.5 months post-RT, 6.73 mmHg (±2.24, P=0.001) and 6.15 mmHg (±1.57, P=0.012) at 4.5 months post-RT, and 8.02 mmHg (±2.73, P<0.001) and 7.91 mmHg (±2.33, P<0.001) at 7.5 months post-RT. The corresponding decreases in the M&L group were not significant at any time post-RT. At 7.5 months post-RT, serum FT3 and FT4 concentrations in C&U group decreased significantly (P<0.05) from before RT to 7.5 months after the end of RT, and TSH concentration increased significantly after RT (P<0.05). In addition, Pearson analysis showed that both FT3 and FT4 was positively correlated with decrease of systolic BP (r= 0.430, P =0.001; r=0.667, P <0.001, respectively) and diastolic BP (r = 0.370, P =0.005; r = 0.469, P < 0.001 respectively). Conclusion The present study suggests that radiotherapy in patients with cervical and upper thoracic esophageal cancer might result in lowering BP, which might be related to thyroid gland damage by radiotherapy.