264. SIGNIFICANCE AND USEFULNESS OF PLASMA SUBSTANCE P CONCENTRATION IN PREDICTING HIGH-RISK PATIENTS FOR ASPIRATION AFTER ESOPHAGEAL CANCER SURGERY

Abstract Background The greatest challenge in postoperative complications of esophageal cancer is the prevention of pulmonary complications, especially aspiration pneumonia. Although the introduction of minimally invasive surgery and intervention in breathing and swallowing rehabilitation can improve the motor function of breathing and swallowing, we reported the possibility that a decline in the swallowing reflex may play a significant role in esophageal cancer patients, many of whom are elderly. In fact, about 80% of esophageal cancer patients in Japan are over 60 years old, and 53% of them have asymptomatic cerebral infarction, about half of which are reported to be found near the basal ganglia, which control the swallowing reflex. The swallowing reflex is controlled by the secretion of substance P, synthesized in the cervical sympathetic ganglia, into the pharynx and trachea upon stimulation of dopamine synthesized in the basal ganglia. Methods To test the hypothesis that patients with preoperative subclinical cerebral infarction are more likely to develop aspiration postoperatively due to decreased substance P secretion. To compare the association between the presence or absence of cerebral infarction near the basal ganglia and serum substance P levels and the development of postoperative aspiration or aspiration pneumonia due to videoendoscopy and video fluorography in patients with thoracic esophageal cancer scheduled for video-assisted esophagectomy by preoperative brain MRI imaging and blood sampling. Results We report the results of an interim analysis of 54 cases in which the measurement of substance P was completed. Male: 39 cases, female: 15 cases. Mean age: 69.3 (49-82) years. Tumor location: Ut/Mt/Lt=13/25/14. MRI showed infarction in or near the basal ganglia in only 2 cases. Median preoperative blood substance P concentration: 48.2 pg/ml. Eleven one patients had postoperative aspiration. Preoperative substance P levels ≥48.2 pg/ml were defined as the High group, and those below 48.2 pg/ml were defined as the Low group. Postoperative aspiration was observed in 2/27 (7.4%) patients in the High group, while 9/26 (34.6%) patients in the Low group, which was significantly higher (p=0.015). Conclusion In fact, subclinical cerebral infarction was much less common than reported and was not useful as a predictor of postoperative aspiration. On the other hand, patients with low preoperative blood substance P levels had a very high risk of developing aspiration postoperatively due to impaired swallowing reflexes, suggesting that preoperative blood substance P levels may be useful in assessing postoperative aspiration risk in patients with thoracic esophageal cancer.