Aggressive and malignant pituitary tumours: state-of-the-art

Abstract

Pituitary adenomas are unique in multiple ways. They are rarely malignant in terms of metastases, yet they may be aggressive. Their cancerous potential is defined in a classic oncological way by the ability to metastasise, and therefore it has been crucial to differentiate this process from aggressive behaviour, characterised as a particularly invasive and/or recurrent behaviour and resistance to common modalities of therapy. Recently, however, important changes have been introduced to the diagnosis and management of aggressive and malignant pituitary tumours including the 4th edition of the WHO classification for endocrine tumours (2017) as well as ESE Clinical Guidelines (2018), although an attempt to establish predictive and/or prognostic markers of clinical aggressiveness remains difficult. In this review, we focus on a group of pituitary tumours causing significant problems in clinical practice and requiring multidisciplinary input. We summarise updates in definitions of tumour invasiveness, aggressiveness and malignant transformation, as well as histological classification, and emphasise the new considerations regarding aggressive and malignant potential and its relationship to therapeutic strategies.

Pituitary Adenomas and Invasiveness from Anatomo-Surgical, Radiological, and Histological Perspectives: A Systematic Literature Review

“…The main features of some PAs include: 1) more aggressive biologic behavior, which typically corresponds to a proliferative index that is higher than usual; 2) an invasive behavior, so that the PAs extend in the extrasellar region and/or histologically invade the surrounding dural, periosteal, or mucosal tissues. Aggressiveness and invasiveness are sometimes used as synonyms, as the two features are frequently present in the same tumor, but they should not be confused as they describe two distinct characteristics of PAs (Figure 1) [1][2][3][4][5][6][7]. .…”

Clinicopathological analysis of 250�cases of pituitary adenoma under the new WHO classification

“…Currently, surgery is still the preferred treatment for invasive PAs. However, due to the similar malignant biological behaviour, total surgical resection of invasive PAs is difficult; the rate of total resection is lower compared with that of non-invasive tumours, and the postoperative recurrence rate is higher, requiring multiple surgical treatments (38). Thus, patients with invasive PAs often need adjuvant drug treatment.…”

Exploring the Role of Novel Medical Therapies for Aggressive Pituitary Tumors: A Review of the Literature—“Are We There Yet?”

“…Pituitary tumors account for approximately 10% to 15% of all intracranial tumors [1], with a prevalence of clinically significant pituitary tumors reported as 80 to 100 cases per 100,000 [2]. The majority are benign and slow growing; however, up to 10% have a more aggressive clinical course [3].…”

“…In the most recent WHO classification in 2017, the term atypical adenoma is no longer recommended due to a lack of evidence for its prognostic value [5][6][7]. It has been more recently proposed that APT be defined clinically as invasive tumors displaying an unusually rapid tumor growth rate or tumor growth despite optimal standard therapies, including surgery, radiotherapy, and chemotherapy [1][2][3]. The new WHO classification describes pituitary tumor subtypes along with histological markers, such as Ki67 > 3%, that may suggest a potential for aggressive clinical behavior [5].…”

“…The new WHO classification describes pituitary tumor subtypes along with histological markers, such as Ki67 > 3%, that may suggest a potential for aggressive clinical behavior [5]. Pituitary carcinomas (PCs), defined by the presence of craniospinal or systemic metastases, are very rare, comprising just 0.2% of all pituitary tumors [1,5]. The mortality rates of PCs are known to be high, historically up to 66% at 1 year following diagnosis [8,9].…”