Initial management of locally advanced and metastatic well-differentiated low-grade (G1) and intermediate-grade (G2) gastrointestinal neuroendocrine tumors

CT: computed tomography; G1: low-grade; G2: intermediate-grade; LAR: long-acting release; MRI: magnetic resonance imaging; PET: positron emission tomography; PRRT: peptide receptor radionuclide therapy; SSTR: somatostatin receptor.

* We obtain surveillance imaging of the abdomen and pelvis with either contrast-enhanced CT or gadolinium-enhanced MRI, along with a CT chest with or without contrast at 3 and 6 months. The frequency of subsequent imaging is based on the pace of disease progression (eg, every 6 months for slowly progressive disease).

¶ Tumor SSTR expression is determined using an SSTR PET-CT or PET-MRI. Only SSTR-positive tumors are likely to benefit from somatostatin analogs or PRRT.

Δ Some patients with tumors that lack uptake on SSTR imaging may still be candidates for a somatostatin analog for symptom control, if needed, but disease control is less certain.

◊ Eligibility criteria for PRRT include tumor SSTR expression, sufficient bone marrow reserve (grade 1 to 2 hematologic toxicity is usually acceptable), creatinine clearance >50 mL/minute, Karnofsky performance status >50, and expected survival greater than 3 months.

§ Somatostatin analog is continued during and after PRRT.

¥ Both agents are equally acceptable, effective therapies for well-differentiated NETs that can be administered with minimal patient discomfort. The cost of lanreotide can be higher than octreotide LAR.