Association between PET-CT accumulation in the hypothalamic /pituitary regions and neuron-specific enolase /primary tumor in limited-stage small cell lung cancer

Abstract Objective: This study aimed to investigate the relationship between positron emission tomography-computed tomography (PET-CT) accumulation at hypothalamic /pituitary regions, tumor, and neuron-specific enolase (NSE) in limited-stage small cell lung cancer. Methods: We analyzed patients who were diagnosed with limited-stage small cell lung cancer at Tokyo Medical University Hospital between July 1, 2019 and May 31, 2023 and who underwent chemoradiotherapy or radiotherapy. Leukocytes, erythrocytes, hemoglobin, platelets, total protein, albumin, NSE, and carcinoembryonic antigen were measured in blood samples taken before the start of treatment. In PET-CT, the maximum standardized uptake value (SUVmax), volume. total lesion glycolysis (TLG) of the hypothalamic /pituitary regions, primary tumor, lymph node metastases were extracted. And total tumor volume (primary tumor and lymph node metastases), total TLG (primary tumor and lymph node metastases) were calculated. Results: A total of 19 patients were selected (mean age 70.1±8.8 years; 13 male and six female). The pathology of all cases was small cell lung cancer. Cases were classified into two groups according to the NSE standard value (16.3 ng/mL); six cases were below the standard value and 13 were above the standard value. The SUVmax in the hypothalamic/pituitary region was 2.95 in the NSE <16.3ng/mL group and 4.10 in the NSE >16.3ng/mL group, showing a statically significant difference (p=0.03).The total tumor volume was 17.8 ml in the NSE <16.3ng/mL group and 98.9 ml in the NSE >16.3ng/mL group, showing a statically significant difference (p<0.01).A correlation coefficient of r=0.458 and p=0.0486 was observed between SUVmax in the hypothalamus/pituitary and NSE. A correlation coefficient of r=0.647 and p<0.01 was observed between total tumor volume and NSE. A correlation coefficient of r=0.53 and p=0.01 was observed between hypothalamic/pituitary TLG and primary tumor TLG. Conclusions: There was correlation between hypothalamic/pituitary activity and tumor activity.