Successful management and 10-year survival of a rectal neuroendocrine tumor with rare systemic metastases via a non-portal venous pathway

Metastatic neuroendocrine tumors (NETs) typically involve the liver and lymph nodes. Metastases in the orbit, heart, and ovary are rare and present unique clinical challenges. We report a woman who was 70 years old at the time of initial presentation with liver metastases from a rectal neuroendocrine tumor. Following a right hepatectomy for liver metastases, she remained free of hepatic recurrence for 10 years. Notably, four years after the right hepatectomy, she developed new metastases in the left orbit, right ventricle, and left ovary, with diplopia as the sole clinical symptom. This clinical course suggests a distinct metastatic pathway associated with the lower rectum that bypasses the portal circulation, consistent with the dual drainage system of the rectal region. Management involved a strategic multimodal approach that includes systemic therapy with everolimus and lanreotide as well as targeted surgical resectioning of the cardiac and ovarian lesions. The orbital lesion achieved a complete response through systemic therapy alone, preserving visual function. Currently, 10 years after the initial treatment, the patient maintains an excellent performance status (ECOG PS 0) while receiving peptide receptor radionuclide therapy (PRRT). This case demonstrates that recognizing atypical metastatic pathways and employing strategic multimodal therapies can achieve long-term survival and functional preservation in rectal NETs.