Background: Diarrhea is part of the carcinoid syndrome and a significant clinical problem in neuroendocrine tumor (NET) patients. Somatostatin analog (SA) treatment usually alleviates carcinoid diarrhea, but little is known about the objective effects of SA on gastrointestinal transport.
Aim: To compare gastrointestinal motility in healthy subjects and NET patients before and during SA treatment.
Methods: Twelve NET patients were studied before and during 4 weeks of SA treatment and were compared with 12 healthy controls. Radio-opaque markers were used for the assessment of total gastrointestinal transit time (GITT). Gastric and small intestinal (SI) transit patterns were described via the external tracking of a small magnetic pill ingested by the subjects.
Results: Compared with controls, NET patients had a significantly shorter GITT (0.7 days (0.5-1.5) vs. 1.9 days (1.0-2.3)), a shorter SI transit time (184 min (74-307) vs. 322 min (131-376)), and a faster SI velocity (2.16 cm/min (0.91-3.66) vs. 1.29 cm/min (0.76-2.60)) (all p < 0.05) but a similar gastric emptying time. SA treatment was followed by a reduction in bowel movements (five per day (3-12) vs. four per day (1-7; p < 0.02)) as well as an increase in GITT (1.4 days (0.5-2.2; p < 0.05)). Further, a trend was observed toward increased SI transit time (253 min (145-344; p = 0.08)). Gastric emptying time increased during SA treatment (19 min (4-200) vs. 179 min (5-389; p < 0.02)). Elevated chromogranin A (CgA), serotonin, and urinary 5-hydroxyindoleacetic acid (U-5HIAA) levels decreased during SA treatment.
Conclusion: NET patients have faster than normal total GITT and SI transit times. SA treatment prolongs gastric emptying and GITT, thereby reducing the number of bowel movements.