Somatostatin-receptor avidity of pancreatic neuroendocrine tumor thrombus in porto-caval venous systems on ^99mTc-Octreotide and posttherapeutic ¹⁷⁷Lu-DOTA-TATE scans

Abstract

A 62-year-old woman with a history of abdominal pain presented with multiple hepatic lesions and dilatation of portal, splenic and superior mesenteric veins on the magnetic resonance imaging referred for a ^99mTc-octreotide scan. Accordingly, similar octreotide-avid lesions were found as well as an uptake in the epigastric region conforming to the anatomy of the portocaval venous system, compatible with a tumor thrombosis. Then, the patient underwent two cycles of therapy with ¹⁷⁷Lu-DOTA-TATE, on that the same appearance was observed. The uptake in the tumor thrombus remained somewhat unchanged, but clinically, a significant improvement of the intractable ascites was achieved.

Keywords

¹⁷⁷Lu-DOTA-TATE - ^99mTc-Octreotide - pancreatic neuroendocrine tumor - somatostatin-receptor - tumor thrombosis

A 62-year-old woman with a history of abdominal pain, episodes of hypotension, and syncope presented for a 99mTc-octreotide scan. On the ultrasonography (USG) performed before, there were multiple heterogeneous and hypoechoic masses in hepatic parenchyma and significant dilatation and intraluminal thrombosis of the portal and splenic veins. Doppler USG also showed intrathrombotic vascular components suggestive of tumor thrombosis. The patient then underwent a gadolinium-enhanced magnetic resonance imaging (MRI) of the abdomen which confirmed multiple hypointense lesions in the liver and portal, splenic and superior mesenteric venous dilatation with heterogenous enhancement [Figure 1]. After receiving an informed consent, whole-body 99mTc-octreotide scan [Figure 2] was performed that demonstrated multiple octreotide-avid lesions in the liver as well as a less intense uptake in the epigastric region conforming to the anatomy of the portal and the splenic venous system as those found on the MRI. Afterward, the patient underwent a liver biopsy. Poorly differentiated neuroendocrine carcinoma of pancreatic origin was confirmed on histopathologic examination. The patient was on Sandostatin LAR treatment for several months before being referred for a radiopeptide therapy with 177Lu-DOTA-TATE as a result of exacerbation of the symptoms and developing intractable ascites. On post-therapeutic whole-body scan one day following intravenous administration of 5550 MBq [150 mCi] of 177Lu-DOTA-TATE [Figure 3a], the same findings were observed as those on the 99mTc-octreotide scan. The patient received another dose of 177Lu-DOTA-TATE therapy 6 months later [Figure 3b]. The ascites improved remarkably by clinical assessment thereafter, but other lesions remained unchanged. Neuroendocrine tumors of pancreatic origin are among the tumors with a predilection for involvement of the portal and caval venous systems through the direct intraluminal extension of malignant tumoral cells. This mechanism is other than the predisposition toward the hypercoagulable state, i.e. venous thrombosis, induced by cancer. The former seems to be prognostically less favorable, because of predictably less response to anticoagulation therapy.[1],[2],[3] Unfortunately, since the uptake can be attributed to radiotracer accumulation either in the activated leukocytes trapped in the clot or malignant tumoral cells, octreotide-based scans seem not to be able to reliably differentiate the two conditions, but CT and MRI are more useful by demonstrating different enhancing patterns.[4],[5] The octreotide avidity of tumor thrombus has been shown in previous reports on 68Ga-DOTA-TATE/NOC positron emission tomography scans,[6],[7],[8],[9] but the response to 177Lu-DOTA-TATE therapy is yet to be investigated. Currently, the effective therapeutic method is surgical resection of the thrombus to alleviate the unpleasant symptoms.[10] In our case, because of the patient's refusal, surgical thrombectomy was not performed, but despite octreotide avidity of the thrombus, two cycles of 177Lu-DOTA-TATE therapy were not remarkably effective. However, a considerable clinical improvement in ascites has been observed, and therefore, this achievement, i.e. symptom alleviation, can be of notable importance. Taken together, further investigations are required to assess the effectiveness of radiopeptide therapy in resolving tumor thrombus from neuroendocrine tumors.

Figure 1: Transverse (a and b) and coronal (c) slices of a gadolinium.enhanced magnetic resonance image show hepatic lesions, ascites (small arrowheads) and dilatation of the portal (small arrow), superior mesenteric (large arrowhead) and splenic (large arrow) veins as well as intraluminal tumor thrombosis

Figure 2: Whole.body (a), tomographic slices (b.d) of the ^99mTc-octreotide scan demonstrate multiple octreotide.avid lesion in the liver as well as uptake matching the anatomy of portal and splenic venous system

Figure 3: Posttherapeutic ¹⁷⁷Lu-DOTA-TATE scans of first (a) and second (b) cycles of therapy shows similar finding as those observed on ^99mTc-octreotide scan

Conflict of Interest

There are no conflicts of interest.

Financial support and sponsorship

Nil.

• References

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Publikationsverlauf

Eingereicht: 16. März 2021

Angenommen: 24. Mai 2021

Artikel online veröffentlicht:
24. März 2022