ENO2 and neoplasm: The following inferences can be drawn from these findings: (1) In small cell lung cancer, the hypothalamus and pituitary gland are involved in tumor growth, particularly primary tumor growth (hypothalamic/pituitary TLG and primary tumor TLG/volume showed a statistically significant positive correlation); (2) NSE reflects the tumor burden, particularly lymph node metastases, and hypothalamus/ pituitary activity; and (3) prophylactic whole-brain irradiation does not eradicate microscopic brain metastases but depresses hypothalamic–pituitary regions, which reduces tumor activity.