From the Guidelines
Axillary neuroendocrine tumors are staged using the TNM classification system, with the American Joint Committee on Cancer (AJCC) staging system being the most commonly used, as recommended by the European Neuroendocrine Tumor Society (ENETS) and supported by recent guidelines 1.
Staging Process
The staging process for axillary neuroendocrine tumors involves:
- Comprehensive imaging, including CT scans of the chest, abdomen, and pelvis
- Somatostatin receptor scintigraphy (Octreoscan) or Gallium-68 DOTATATE PET/CT to assess the extent of disease
- Laboratory tests, including chromogranin A, 5-HIAA, and specific hormones related to symptoms
- Tissue diagnosis through core needle biopsy or excisional biopsy, with immunohistochemical staining for neuroendocrine markers (synaptophysin, chromogranin A, CD56) and Ki-67 proliferation index to determine tumor grade
Importance of Primary Site Identification
Since axillary neuroendocrine tumors are often metastatic, identifying the primary site is crucial for proper staging and treatment planning, as the primary tumor site has an impact on the prognosis in advanced disease 1.
Treatment Decisions
The staging process guides treatment decisions, including:
- Surgical resection
- Somatostatin analogs (octreotide LAR 20-30 mg monthly or lanreotide 90-120 mg monthly)
- Targeted therapies
- Peptide receptor radionuclide therapy, depending on disease extent and tumor characteristics, with the goal of improving morbidity, mortality, and quality of life outcomes 1.
From the Research
Staging of Axillary Neuroendocrine Tumors (NETs)
The staging of axillary neuroendocrine tumors (NETs) is a complex process that involves various imaging modalities.
- Accurate staging is crucial for therapy planning, but it remains a challenge 2.
- Imaging techniques such as positron emission tomography (PET) scans, computed tomography (CT) scans, and magnetic resonance imaging (MRI) are used to stage NETs 2, 3, 4.
- A combination of morphologic and molecular imaging is recommended for accurate staging 2.
- The choice of imaging modality depends on the location of the primary and metastatic lesions 4.
Imaging Modalities
- PET/CT is a sensitive imaging modality for detecting metastatic lymph nodes and pulmonary lesions 3.
- MRI is superior to other modalities for assessing liver metastasis 3, 4.
- CT scans are typically the primary imaging modality for evaluating NETs, while MRI is used as a complementary modality 4.
- Nuclear medicine imaging is also widely used in NET assessment 4.
Grading Schemes
- A novel grading scheme, known as the NETPET grade, has been proposed to describe the joint results of FDG and somatostatin receptor imaging PET scans in staging subjects with NETs 5.
- The NETPET grade has been shown to be significantly correlated with overall survival and may be a useful prognostic imaging biomarker in NETs 5.
Clinical Implications
- The imaging results can influence treatment decisions, and individual treatment strategies can benefit from complementary information from different imaging modalities 3.
- A multimodality approach, including a combination of chemotherapy regimen and surgical resection, may be used to manage axillary NETs 6.