Beyond Tumor Control in Sporadic Neuroendocrine Tumor: Metabolic and Bone Health During Treatment with Somatostatin...

Background: Somatostatin analogs (SSAs) are widely used in the treatment of neuroendocrine tumors (NETs). Despite SSAs having a favorable safety profile, their long-term impact on glucose metabolism and bone health remains uncertain. This study aimed to compare glycemic, calcium-phosphorus, and densitometric parameters between patients with sporadic NETs receiving SSA therapy and untreated patients. Methods: A retrospective observational study enrolling patients with sporadic NETs was conducted at Federico II University of Naples, Endocrinology Unit, ENETS Center of Excellence. Results: A total of 40 patients were enrolled: 18 (45%) treated with SSA (SSA+) and 22 (55%) untreated (SSA-). The median duration of SSA treatment was 24.5 months (range 12-180). HbA1c was significantly higher in the SSA+ group compared to SSA- (median 6.20% vs. 5.70%; p = 0.027). Corrected calcium levels were significantly lower in SSA+ patients (8.90 vs. 9.47 mg/dL; p = 0.045). No significant differences were observed between groups in phosphorus, vitamin D or PTH levels. Median lumbar T-score was -0.15 in SSA+ vs. -1.10 in SSA- (p = 0.256); lumbar BMD was 1.23 vs. 0.97 g/cm² (p = 0.127). Femoral neck T-score was -0.85 vs. -1.55 and femoral BMD was 0.89 vs. 0.78 g/cm². The prevalence of osteoporosis and osteopenia did not differ significantly between groups. Within the SSA+ group, treatment duration showed no significant correlations with any densitometric parameter. Conclusions: SSA treatment in patients with sporadic NETs is associated with a significant impairment of glycemic control. The reduction in serum calcium observed in SSA+ patients may indicate an indirect effect on calcium-phosphorus metabolism that warrants further investigation. These findings support careful metabolic assessment during follow-up. Although routine densitometric evaluation based solely on SSA exposure does not appear warranted, bone health assessment may be considered according to individual skeletal risk factors and the patient's overall clinical profile.