The Natural History of Residual Pituitary Adenomas and Risk Factors Associated with Tumor Progression after Previous Surgical Treatment

Background: Pituitary adenomas account for approximately 10 to 20% of primary intracranial tumors. Endoscopic transsphenoidal surgery (ETSS) is the treatment of choice, but a complete surgical resection is not always achievable and 50 to 60% of adenomas continue to develop after subtotal resection. The natural history of these residual tumors is variable and remains poorly understood. Consequently, the best approach, that is watchful waiting, irradiation, medical therapy or reoperation, is not established.

Objectives: The purpose of this study was to identify prognostic factors involved in the development of residual pituitary adenomas and describe their natural history.

Methods: Between 2007 and 2021, a total of 121 patients with residual pituitary adenomas after ETSS were studied retrospectively. Patients were considered eligible if they had residual adenomas without postoperative radiotherapy and pharmacotherapy. The clinical follow-up period ranged from 20 to 180 months and the radiological period ranged from 9 to 162 months. Age, gender, type of surgery, radiological findings including preoperative tumoral volume and dimensions, residual volume and its localization, preoperative bleeding, T2 signal, and contrast enhancement pattern along with immunohistochemical findings such as Ki-67, p53, CAM 5.2, and SF-1 were studied as possible risk factors for tumor progression. The tumor growth-free survival rate (TGFSR) and residual tumor volume doubling time (TVDT) were calculated and correlated to those variables.

Results: A total of 108 nonfunctioning and 13 functioning pituitary adenomas were included in this study. The median TVDT was 25.9 months. Except for the reactivity to FSH/LH in the immunohistochemistry (p = 0.024), none of the others variables showed a statistically significant correlation with the TVDT: age (p = 0.232), type of surgery (p = 0.935), preoperative tumor volume (p = 0.542), cavernous sinus invasion (p = 0.818), sphenoidal invasion (p = 0.106), suprasellar extension (p = 0.632), preoperative intratumoral bleeding (p = 0.626), preoperative tumor T2 signal (p = 0.851), preoperative tumor contrast enhancement pattern (p = 0.337) Ki-67 (p = 0.833), p53 (p = 0.386), SF-1 (p = 0.560), and CAM 5.2 (p = 0.328).

Conclusion: Despite the high prevalence of residual pituitary adenomas, evidence on the natural history of these entities is scarce. Apart from the immunohistochemical detection of FSH/LH receptors, no other risk factors for tumor progression were identified. Therefore, decision-making whether to treat a residual pituitary adenoma and which treatment to choose remains difficult and complex. It must be made on a case-by-case basis.

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Artikel online veröffentlicht:
07. Februar 2025