Usefulness of a clinicopathological classification in predicting treatment-related outcomes and multimodal therapeutic approaches in pituitary adenoma patients: retrospective analysis on a Portuguese cohort of 129 patients from a tertiary pituitary center

Purpose A clinicopathological classification has been designed to predict recurrence/progression in patients with pituitary adenomas (PAs). We aimed to study its usefulness in predicting PAs that will have a challenging disease course and may require more often complex multimodal and multiple therapeutic approaches. Methods Retrospective analysis of 129 patients with PAs operated in our institution between 2001 and 2020 (84 non-clinically functioning PAs, 32 acromegaly, 9 Cushing's disease, 2 prolactinomas and 2 thyrotropinomas). Grading was based on invasion and proliferation: 1a (non-invasive, non-proliferative; n = 59), 1b (non-invasive, proliferative; n = 17), 2a (invasive, non-proliferative; n = 38), and 2b (invasive, proliferative; n = 15). Results Of the 129 patients, 68 (52.7%) were females, and the mean age at diagnosis was 53.7 +/- 15.4 years. The mean follow-up duration was 93.1 +/- 61.8 months. Grade 2b PAs when compared to other grades (2b-2a-1b-1a) had significantly higher rates of persistent tumor remnant within 1-year after operation (93-78-18-30%; p < 0.001), active disease at last follow-up (40-27-12-10%; p = 0.004), re-operation (27-16-0-5%; p = 0.023), irradiation (53-38-12-7%; p < 0.001), multimodal treatment (67-49-18-25%; p = 0.003), multiple treatment (33-27-6-9%; p = 0.017). Patients with grade 2b PAs also required a higher mean number of treatments (2.6-2.1-1.2-1.4; p < 0.001). Conclusions This clinicopathological classification appears to be a useful grading system to identify PAs that may be more refractory and more often require complex multimodal and multiple therapeutic approaches. Invasive PAs, especially grade 2b tumors, may be more likely to need complex treatment approach, including radiotherapy, and may display higher rates of active disease at last follow-up, despite receiving higher number of treatments.