Search

Purpose: The synergic combination of oxaliplatin and capecitabine has demonstrated activity against various gastrointestinal cancers, including colon cancer. We therefore undertook this phase II study to test this first-line combination in patients with metastatic adenocarcinoma of the esophagus, gastroesophageal junction and gastric cardia., Patients and Methods: Forty-three patients with histologic or cytologic confirmation of the above malignancy were recruited. The cohort had Eastern Cooperative Oncology Group performance statuses of 0, 1 and 2 in 47%, 51%, and 2%, respectively. Median age was 61 years (range 32-80). All had adequate organ function. Initially, patients were prescribed 130 mg/m2 intravenously on day 1 and capecitabine 1000 mg/m2 orally twice a day, on days 1-14 of a 21-day cycle. Four treatment-related deaths in the first 24 patients led to a reduction in capecitabine to 850 mg/m2 orally twice a day, days 1-14, for the remainder of the cohort., Results: The tumor response rate was 35% [95% confidence intervals (CI) 23% to 50%]. All responses were partial; seven of 24 occurred before the capecitabine dose reduction, and eight of 19 after. Median time to tumor progression was 4 months (95% CI 3.1-4.6), and median survival 6.4 months (95% CI 4.6-10). To date, there have been 36 deaths. Four were treatment-related (one infection, two myocardial infarctions, one respiratory failure), and all occurred before the capecitabine dose reduction. Notable grade 4 events from the entire cohort included diarrhea (two patients), vomiting (three), dyspnea (one), thrombosis (two) and anorexia (two). Grade 3 events included nausea (12 patients), diarrhea (12), fatigue (10), abdominal pain (seven), vomiting (six), dyspnea (six), hypokalemia (six), dehydration (five), hypokalemia (five) and infection (four)., Conclusions: Oxaliplatin and capecitabine in combination demonstrates activity in metastatic adenocarcinoma of the esophagus, gastroesophageal junction and gastric cardia. The lower dose (capecitabine 850 mg/m2 orally twice a day, days 1-14, and oxaliplatin 130 mg/m2 intravenously on day 1) yielded an acceptable toxicity profile and merits further study.

Background: Dietary nitrate increases saliva nitrite levels and swallowed saliva is the main source of nitrite entering the acidic stomach. In acidic gastric juice, this nitrite can generate potentially carcinogenic N-nitrosocompounds. However, ascorbic acid secreted by the gastric mucosa can prevent nitrosation by converting the nitrite to nitric oxide., Methods: To study the potential for N-nitrosocompound formation in a model simulating salivary nitrite entering the acidic stomach and the ability of ascorbic acid to inhibit the process. Concentrations of ascorbic acid, total vitamin C, nitrite, nitrosomorpholine, oxygen and nitric oxide were monitored during the experiments., Results: The delivery of nitrite into HCl containing thiocyanate resulted in nitrosation of morpholine, with the rate of nitrosation being greatest at pH 2.5. Under anaerobic conditions, ascorbic acid converted the nitrite to nitric oxide and prevented nitrosation. However, in the presence of dissolved air, the ascorbic acid was ineffective at preventing nitrosation. This was due to the nitric oxide combining with oxygen to reform nitrite and this recycling of nitrite depleting the available ascorbic acid. Further studies indicated that the rate of consumption of ascorbic acid by nitrite added to natural human gastric juice (pH 1.5) was extremely rapid with 200 micromol/l nitrite consumed 500 micromol/l ascorbic acid within 10 s., Conclusions: The rapid consumption of ascorbic acid in acidic gastric juice by nitrite in swallowed saliva indicates that the potential for acid nitrosation will be maximal at the GO junction and cardia where nitrite first encounters acidic gastric juice. The high incidence of mutagenesis and neoplasia at this anatomical location may be due to acid nitrosation arising from dietary nitrate.

Gas eructation function of the gastroesophageal sphincter (GES) was investigated in 6 conscious dogs before and after a sleeve was placed around the GES and gastric cardia and during IV infusion of a beta-adrenergic amine (epinephrine). To induce eructation, nitrogen gas was insufflated (351.4 +/- 2 ml/min; mean +/- SEM) into the stomach through 1 channel of a 4-lumen catheter. After baseline studies and epinephrine infusion studies were completed in each dog, surgery was done to limit partially gastric distension by intraluminal contents by placing a silicone rubber sleeve around the GES and the first few centimeters of the cardia. Gastroesophageal sphincter pressure was 31.8 +/- 2.2 mm of Hg in baseline studies, 17.3 +/- 1.3 mm of Hg during epinephrine infusion (P. less than 0.003), and 30.3 +/- 2.2 mm of Hg after the sleeve was placed around the GES and cardia. During insufflation, gastric pressures before eructation increased to 5.74 +/- 0.41 mm of Hg before and to 15.15 +/- 1.63 mm of Hg after cardia sleeve placement (P less than 0.001). Eructation occurred at intervals of 1.83 +/- 0.41 minutes before cardia sleeve placement, and eructations were not observed with the sleeve in place. Before the sleeve was placed, administration of epinephrine resulted in an eructation interval of 0.84 +/- 0.09 minutes, which was significantly different from that in the same dogs given no drugs (P less than 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

In 16 normal subjects the pressure characteristics of the cardiac sphincter have been examined. The effect of perfusing the gastric aspect of the sphincter mucosa has been studied by comparing the effects of saline with those of solutions where pH ranged from 1.0 to 8.0. Acid perfusion produced an increase in sphincteric pressure, particularly at pH 3.0. This suggests that a physiological mechanism exists which can increase the barrier pressure to gastrooesophageal reflux during periods of active secretion of the stomach, as occurs in digestion.

Both hog gastrin and synthetic gastrin stimulate the cardiac sphincter to increase tone and augment the resistance to reflux. Endogenous gastrin has a similar effect, and gastrin also stimulates the secretion of acid which has also been found to increase the resistance of the sphincter, but the effect of gastrin appears to be independent of the secretory stimulus.