Randomized, placebo-controlled trial of gastric acid-lowering therapy on duodenal polyposis and relative adduct labeling in familial adenomatous polyposis

PURPOSE

Bile has been implicated in the pathogenesis of duodenal polyps in patients with familial adenomatous polyposis. In vitro experiments have shown that familial adenomatous polyposis bile is capable of producing DNA adducts. This effect can be ameliorated by increasing the pH of the incubate. The aim of this double-blind randomized placebo-controlled trial was to examine the effect of oral ranitidine on duodenal polyposis in a group of patients with familial adenomatous polyposis.

METHODS

Twenty-six patients with familial adenomatous polyposis were randomly assigned to ranitidine 300 mg daily or placebo for six months after baseline endoscopy. Polyp counts were performed and biopsy specimens taken to detect DNA adducts by 32P-postlabeling.

RESULTS

No difference was seen in polyp numbers (P = 0.9) or relative adduct labeling (P = 0.7) after treatment with ranitidine or placebo.

DISCUSSION

Acid suppression therapy does not seem to improve duodenal polyposis despite in vitro findings. On the other hand, ranitidine does not exacerbate actual (or markers of) neoplasia in this highly tumor-prone condition.

A randomised study to determine whether routine intravenous magnesium supplements are necessary in patients receiving cisplatin chemotherapy with continuous infusion 5-fluorouracil

Cisplatin is an effective antineoplastic agent, but can cause renal tubular damage leading to urinary magnesium wasting and hypomagnesaemia. Cisplatin and 5-fluorouracil, when used in combination, have synergistic antitumour activity in upper gastrointestinal malignancies, but it is unclear whether they have additive effects on renal magnesium loss. To determine the optimal regimen for magnesium supplementation in these patients, we have conducted a randomised trial of routine intravenous magnesium supplements compared with magnesium given on an 'as required' basis. 32 patients were randomised to receive magnesium intravenously in prehydration and posthydration fluids with cisplatin chemotherapy, or to receive magnesium only when the serum level was low. 5-fluorouracil was given as a continuous infusion. Serum magnesium was measured on admission for each cycle of chemotherapy and an interim measurement performed between each cycle. 28 patients were evaluable. All patients randomised to receive magnesium on an 'as required' basis had at least one episode of hypomagnesaemia. On subsequent admissions for chemotherapy (cycles 2 and 3), the mean serum magnesium level was significantly lower in these patients compared with patients who received magnesium routinely (P < 0.05). After omission of magnesium from the first cycle of cisplatin, magnesium supplements were necessary in 50% of subsequent cycles, usually by the second or third cycle. Moreover, there were several instances of symptomatic hypomagnesaemia requiring further intravenous supplements in mid-cycle. Patients treated with a combination of cisplatin and 5-fluorouracil should be given intravenous magnesium supplements with each cycle of cisplatin chemotherapy. Nevertheless, episodes of hypomagnesaemia still occur, and additional intravenous supplements may be required, highlighting the importance of measuring this electrolyte.