Lutathera Peptide Therapy Worked Even on Liver Tumors That Didn't Show Up on Diagnostic PET Scans

This is a clinical case report of a single 73-year-old male patient. The diagnostic workup included 68Ga-DOTATATE PET/CT, which identified both positive and negative liver lesions along with extrahepatic metastases. Histopathological biopsy of a PET-negative lesion was performed to rule out secondary malignancy. After confirming neuroendocrine origin with high somatostatin receptor expression, 177Lu-DOTATATE therapy was initiated with close monitoring of PET-negative lesions via post-therapeutic scintigraphy and follow-up PET/CT.

In standard practice, a negative PET scan for a specific lesion often means that lesion won't be targeted by therapy. This case challenges that assumption — showing that some PET-negative tumors can still respond to peptide receptor therapy. This has important implications for treatment decisions, as some patients with mixed PET-positive and PET-negative disease might benefit from PRRT even when not all metastases are visible on diagnostic imaging.

Peptide receptor radionuclide therapy is one of the most important advances in neuroendocrine tumor treatment. The standard treatment paradigm relies on diagnostic PET scans to select eligible patients and predict which lesions will respond. This case report reveals a potential gap in that paradigm — false-negative PET scans could lead to undertreating patients who might actually benefit. It raises questions about whether biopsy confirmation should play a larger role in treatment decisions when PET results are discordant.

This is a single case report, which represents the lowest level of clinical evidence. The findings may not be generalizable to other patients or tumor types. The reason for the discordance between diagnostic PET (negative) and therapeutic uptake (positive) is not fully explained. Quantitative uptake values were not reported. Long-term survival outcomes were not described.