What Is a Pituitary Neuroendocrine Tumour (PitNET)?
Pituitary tumours grow from the pituitary gland, a small oval-shaped structure divided into anterior and posterior lobes. This gland releases hormones that regulate growth, metabolism, and reproduction, and in turn control the activity of other glands.
Pituitary tumours make up about 10–15% of intracranial tumours. Most remain benign, but their close proximity to critical neurological and vascular structures, such as the optic chiasm and cranial nerves, can trigger severe neuroendocrine dysfunction.
In 2022, the World Health Organisation (WHO) renamed these tumours from pituitary adenomas to Pituitary Neuroendocrine Tumours (PitNET). The term “adenoma” implies benign behaviour, which does not always match how pituitary tumours act. By classifying them as PitNET, WHO highlighted their possible origin in neuroendocrine cell lineages and expanded the molecular framework used to classify these tumours.
Functioning vs Non-Functioning PitNETs
Doctors classify pituitary tumours as functioning or non-functioning PitNETs based on hormone production. Functioning PitNETs secrete abnormal amounts of biologically active hormones, which can drive overt endocrine disorders. Elevated hormone levels may cause conditions such as acromegaly, prolactinoma, and Cushing’s disease. These functioning tumours make up about 60–70% of all pituitary cases.
Non-functioning PitNETs, by contrast, do not release hormones. Their symptoms arise mainly from mass effect: as the tumour grows, it compresses nearby structures and produces headaches, raised intracranial pressure, or blurred vision. Non-functioning tumours are slightly less common, accounting for 30–40% of pituitary cases.
Pituitary Neuroendocrine Tumour Symptoms
Because this tumour affects the pituitary gland, which regulates hormone secretion, symptoms mainly arise from disruption of normal hormonal function.
In non-functioning pituitary tumours, symptoms usually result from the mass effect of the tumour and may include:
- Headaches
- Restricted eye movement
- Hypopituitarism (reduced hormone production)
- Hyperprolactinaemia (elevated prolactin levels in the blood)
Functioning pituitary tumours actively secrete hormones and can lead to hormonal imbalances such as:
- Acromegaly (excess growth hormone causing enlargement of the hands and feet)
- Cushing disease (excess cortisol leading to weight gain, high blood sugar and high blood pressure)
- Hyperthyroidism (overactive thyroid causing weight loss, rapid heart rate and sweating)
- Hypergonadism (rate; may cause enlargement of the ovaries or testes)
How PitNETs Are Diagnosed
PitNET diagnosis starts with a CT and/or MRI scan along with a complete hormonal assessment. When a patient presents with a macroadenoma or a microadenoma larger than 6mm, the healthcare team may recommend laboratory testing to check for hormonal abnormalities, even if symptoms are absent. Common hormonal imbalances include hypogonadism and growth hormone deficiency, followed by hypothyroidism and adrenal insufficiency. Hormonal testing also helps determine whether the PitNET is functioning or non-functioning, as treatment approaches differ. Surgery is usually the first-line treatment for non-functioning PitNETs, while functioning PitNETs often start with medical therapy.
Clinicians then use imaging to further evaluate the tumour. MRI may be performed with or without contrast; when contrast is used, it helps distinguish the tumour from normal pituitary tissue. Contrast-enhanced MRI also helps define tumour size, extent, and proximity to critical structures. If the tumour lies far from the optic chiasm and the patient has no visual symptoms, clinicians may not require an ophthalmic examination. However, if visual symptoms develop, this may indicate tumour growth toward the optic chiasm and prompt consideration of surgery.
PitNETs Treatment and Options
Surgery is the first-line treatment option for PitNETs. Transsphenoidal surgery (TSS) is the most commonly used approach, with outcomes depending on the size and type of the tumour. The goal of surgery varies by tumour type. In functioning tumours, surgery can achieve remission and reduce hormone excess. In non-functioning tumours, surgery mainly aims to relieve symptoms such as headaches or improve vision.
In some cases, clinicians combine surgery with medical therapy using somatostatin analogues or dopamine agonists. Somatostatin analogues bind to somatostatin receptors, suppress hormone secretion, and limit tumour growth. Dopamine agonists serve as a common treatment for prolactinomas, where they can induce tumour shrinkage. Clinicians may also use these drugs alongside radiation therapy in resistant or invasive tumours.
Radiation therapy for PitNETs includes stereotactic radiosurgery or conventional radiotherapy. However, radiation carries a risk of long-term endocrine dysfunction, so the healthcare team must carefully weigh its benefits and risks for each patient. Researchers are also exploring immune checkpoint inhibitors as a potential alternative to more toxic treatment options.
PitNET Prognosis and Life Expectancy
PitNET prognosis largely depends on whether the tumour is functioning or non-functioning. Non-functioning PitNETs generally have an excellent prognosis when clinicians treat them early with surgery and, in some cases, radiation therapy. Functioning PitNETs, such as those causing acromegaly or Cushing disease, are often associated with comorbidities and long-term complications.
Early detection plays a key role in improving outcomes, as tumour growth can compress critical brain structures and reduce the likelihood of successful surgical removal. Overall, small, slow-growing benign tumours have an excellent prognosis and respond well to first-line treatment options.
Living With PitNETs
Living with PitNETs can place significant emotional and physical strain on both patients and caregivers, from diagnosis through treatment and beyond. Patients may experience depression, anxiety, and cognitive dysfunction, which are common comorbidities associated with both the tumour and its treatment. Chronic hormonal imbalances can further impact and reduce quality of life.
Patients may also develop neuropsychiatric symptoms due to hormonal disturbances and the effects of ongoing treatments such as medications, surgery, and radiation therapy. However, personalised and comprehensive treatment can improve or even reverse some neurobehavioural symptoms in certain patients. Many patients require lifelong monitoring to detect tumour recurrence or manage hormone deficiencies, such as hypopituitarism.
Managing PitNETs often requires a multidisciplinary team, including neurosurgeons and endocrinologists, to address the wide-ranging effects of hormonal dysfunction and support overall quality of life.
Support for families and carers
Although most PitNETs are slow-growing and less aggressive than high-grade brain cancers, they can still have a significant impact on daily life. Hormone imbalances, vision changes, fatigue, and the stress of ongoing monitoring can be challenging for both patients and their families.
Accessing support early can improve quality of life, help manage symptoms, and keep patients and families informed about the latest research and treatment advances.
Visit our Support Hub for more information.
References
- Shafiq I, Anastasopoulou C. Pituitary Adenoma. [Updated 2025 Nov 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554451/
- Cui, S., Chen, S., Wu, X., & Wang, Q. (2024, 2024-April-22). Research status and prospects of pituitary adenomas in conjunction with neurological and psychiatric disorders and the tumor microenvironment [Review]. Frontiers in Neuroscience, Volume 18 – 2024. https://doi.org/10.3389/fnins.2024.1294417
- Whyte, E., Nezu, M., Chik, C., & Tateno, T. (2023, 12). Update on Current Evidence for the Diagnosis and Management of Nonfunctioning Pituitary Neuroendocrine Tumors. Endocrinol Metab, 38(6), 631-654. https://doi.org/10.3803/EnM.2023.1838
- Wu, N., Wu, N., Wang, N., & Zhu, Y. (2025, 2025/10/01/). Progress in the pathogenesis and treatment of pituitary neuroendocrine tumors (PitNETs): From molecular mechanisms to emerging therapies. Molecular and Cellular Probes, 83, 102039. https://doi.org/https://doi.org/10.1016/j.mcp.2025.102039