3D volume growth rate may open new perspectives for the classification of aggressive pituitary adenomas

The 2022 WHO classification states no histological grading exists to assess pituitary adenoma (PA) aggressiveness. The European Society of Endocrinology refers to the term "unusually rapid growth rate" when defining an aggressive PA. This study aimed to evaluate three-dimensional volume growth rate (3DVGR) in multiple PAs and correlate it with tumor progression and histopathology.

Patients with growing or proliferative PAs who underwent surgery were retrospectively selected. Gadolinium-enhanced 3D T1-weighted MRI was required.

A total of 76 3DVGR measurements were performed on 50 nonproliferative and 25 proliferative PAs, with median 3DVGRs of 21.2%/year and 60.2%/year, respectively (P < .0001). ROC analysis (AUC 0.992, P < .001) defined three 3DVGR groups: <50%/year, ≥50%, and <80%/year, ≥80%/year with a median PFS of 99.0, 39.0, and 7.0 months, respectively. In tumors with 3DVGR <50%/year, proliferative status had no significant progression-free survival impact (P = .381). In contrast, proliferative tumors with 3DVGR ≥50%/year had worse outcomes than those with 3DVGR <50%/year (P < .001). In multivariate analysis, only 3DVGR ≥50%/year predicted early progression (P < .001), unlike proliferative status. Combining 3DVGR ≥80%/year or 50% ≤3DVGR < 80%/year with Ki67 ≥ 8% identified 12 PAs with a median PFS of 8.5 months vs 64 months in others.

PA proliferation may be categorized as: <10%/year: non and/or slowly progressive, 10-49%/year: slowly progressive, 50-79%/year: progressive, ≥80%/year: highly progressive. 3DVGR appears to be a valuable tool to evaluate PA proliferation alongside histology.