Reduced Pineal Gland Volume in Oncology Patients: Association with Chemotherapy Duration

Background and Objectives: The pineal gland is a neuroendocrine structure whose function can be disrupted in patients with malignancies. This study examines the differences in pineal gland volume between oncology patients and healthy controls, as well as the relationship between volume and the duration of chemotherapy. Materials and Methods: A retrospective study included 400 participants, divided into two groups: 200 oncology patients and 200 healthy controls. The pineal gland volume was measured using MRI scans, utilizing T1-sagittal, T2-coronal/axial sections, and post-contrast 3D T1W MPRAGE tomograms. The volume was calculated based on the ellipse approximation formula: V = (L × H × W)/2. The study analyzed the relationships between pineal gland volume and factors such as age, sex, primary tumor origin, and the duration of chemotherapy. Results: The pineal gland volume was significantly smaller in oncology patients in comparison with the healthy controls (p < 0.001). The average volume in oncology patients was 32.41 ± 16.79 mm³, whereas in healthy controls, it was 59.26 ± 29.99 mm³. A significantly smaller pineal gland volume was observed in patients with malignancies, regardless of sex, with no notable differences between groups. Age also did not significantly influence gland volume (p > 0.05). The primary tumor site did not significantly influence gland volume (p > 0.05). A moderate positive correlation was observed between the duration of chemotherapy and pineal gland volume (ρ = 0.322; p = 0.007). Conclusions: The pineal gland showed reduced volume in oncology patients compared to controls. The observed positive correlation with chemotherapy duration should be interpreted cautiously and may reflect survivorship bias rather than direct treatment effects.