SSTR2 and neoplasm: In addition, SSTR2 isinvolved in antitumor responses in the body, and its low expression may promotetumor cell proliferation and migration (18).Research has shown that highly differentiated tumor cells typically have high SSTR2expression, whereas poorly differentiated tumor cells have low SSTR2 expression,resulting in lower sensitivity of 68Ga-DOTA-SSA probes (19,20).Therefore, 68Ga-DOTA-SSA probes for metastatic paragangliomas used inclinical practice may need to be combined with other investigations to exclude thepossibility of liver metastases.