Vitamin D Deficiency and Replacement Challenges in Type 1 Gastric Neuroendocrine Tumors: A Comparative Study.

Vitamin D deficiency was significantly more prevalent in the type 1 gNET group compared with the EP-NET group.

• VDD prevalence was 92.3% in the gNET group versus 46.2% in the EP-NET group (p = 0.03, OR: 14).
• The study included 26 patients total: thirteen with type 1 gNET and thirteen with age- and sex-matched EP-NET.
• The cohort was followed at a tertiary referral center between 2010 and 2025.
• Dietary adherence did not differ between groups, suggesting disease-specific rather than dietary mechanisms.

Type 1 gNET patients required significantly higher daily cholecalciferol doses for vitamin D normalization than EP-NET patients.

• Mean daily cholecalciferol dose was 3198.9 ± 1629 IU/day in gNET versus 1580 ± 1121 IU/day in EP-NET (p = 0.008).
• gNET patients more frequently required multiple supplementation formulations (38.5% vs. 0%, p = 0.04).
• Multivariable linear regression analysis restricted to VDD patients confirmed that gNET was independently associated with higher daily cholecalciferol dose requirements (p = 0.037).
• Time and dose required for normalization, supplementation formulations, bone status, and dietary habits were all analyzed in the study.

Bone impairment was significantly more common in the type 1 gNET group than in the EP-NET group.

• Bone impairment, defined as osteoporosis or osteopenia, was present in 61.5% of gNET patients versus 15.4% of EP-NET patients (p = 0.04, OR: 8.8).
• This difference was observed irrespective of dietary habits, which did not differ between groups.
• Type 1 gNET arises in the setting of autoimmune chronic atrophic gastritis and secondary hypergastrinemia, which may contribute to disease-specific mechanisms of bone involvement.

Type 1 gastric NETs arise in the context of autoimmune chronic atrophic gastritis and secondary hypergastrinemia, which may underlie disease-specific vitamin D malabsorption mechanisms.

• Vitamin D deficiency has been associated with bone impairment and adverse outcomes in patients with neuroendocrine tumors generally.
• Data specifically addressing gNET and vitamin D status were described as limited prior to this study.
• The authors suggest that disease-specific mechanisms rather than dietary differences account for the higher VDD burden and supplementation requirements in gNET.

The study design was a retrospective, comparative analysis at a single tertiary referral center with an age- and sex-matched control cohort.

• A total of 26 patients were included: 13 with type 1 gNET and 13 with EP-NET matched by age and sex.
• The study period spanned from 2010 to 2025.
• Variables analyzed included VDD prevalence, time and dose required for normalization, supplementation formulations used, bone status, and dietary habits.