Background and Approach
Background: Central nervous system (CNS) neoplasms are a diverse group of disorders, many of which are rare, poorly understood, and infrequently encountered in clinical practice. Because of their low incidence, these neoplasms often lack the robust data and clinical guidelines that guide more common CNS tumor management. As a result, they frequently pose diagnostic and therapeutic challenges, leading to delayed or suboptimal patient care. Additionally, limited research on these rare CNS neoplasms exacerbates the difficulty in understanding their pathology, treatment options, and long-term outcomes.
The “National Initiative for Rare and Uncommon CNS Tumors (NIRUCT)” seeks to address these challenges by creating a national-level database that encourages clinicians across the country to report rare CNS tumors. The registry will consolidate invaluable data from multiple sources, fostering a deeper understanding of these rare conditions and facilitating better clinical practices, more accurate diagnoses, and improved patient outcomes.
Approach: Our strategy is designed around collaboration, data sharing, and fostering a culture of continuous learning among healthcare professionals. The registry will not only serve as a powerful research tool but will also support clinical practice by enabling clinicians to stay informed and make evidence-based decisions. This approach empowers clinicians by providing them with the resources needed to tackle rare cases effectively.
What is a Rare Central Nervous System Neoplasm?
According to the UK Rare Diseases Framework, a rare disease is defined as a condition affecting fewer than 1 in 2,000 individuals.1 The National Cancer Institute defines rare cancers as those that affect fewer than 40,000 people annually in the United States.2 Despite the lack of a universally agreed-upon definition for rare neoplasms within the World Health Organization (WHO) tumor classification systems or the National Cancer Institute, and particularly for central nervous system (CNS) tumors, there is a clear need for a working framework to guide recognition and reporting.
As part of the National Initiative for Rare and Uncommon CNS Tumors (NIRUCT), the following tentatively proposed working definition is suggested to facilitate awareness, documentation, and research.* A rare or extremely uncommon CNS neoplasm is defined as a primary, histopathologically confirmed tumor of the central nervous system that:
- Occurs infrequently within the CNS, either in the general population or within large oncologic or neuropathologic datasets, and/or
- Is more typically found in other anatomical sites, but when found in the CNS, is proven to be of primary CNS origin (i.e., there is no evidence of an extracranial primary tumor)
- These tumors must be primary to the central nervous system and must not represent metastasis from another organ.
- They must also be histopathologically confirmed.
- In certain instances, the tumor may resemble neoplasms more commonly found outside the CNS, but if it arises within the brain or spinal cord without evidence of a primary tumor elsewhere, it should be reported and studied as a rare or extremely uncommon primary CNS neoplasm.
For example, alveolar soft part sarcoma is a tumor that typically arises in the muscles of the thigh or buttock. However, when it occurs intracranially and no primary tumor is found elsewhere in the body, it should be classified as a case of primary intracranial alveolar soft part sarcoma. Though extremely rare, such cases are critical to identify and report, as they contribute valuable knowledge to the medical and scientific community. Other examples of rare or extremely uncommon CNS tumors may include primary intracranial rhabdomyosarcoma, primary intracranial congenital glioblastoma and primary intramedullary germinoma of the spinal cord.
This definition is not intended to replace existing clinical or pathological guidelines but to serve as a conceptual aid in the early identification and reporting of rare or extremely uncommon primary CNS tumors within the scope of this national initiative. This definition is intended solely for the purposes of this initiative and is not meant to serve as an official or universally accepted classification.
1. National Cancer Institute. About rare cancers \[Internet]. Bethesda (MD): National Cancer Institute; \[posted 2019 Feb 27; cited 2025 Sep 05].
Available from: www.cancer.gov
2. Department of Health and Social Care. The UK Rare Diseases Framework \[Internet]. London: Department of Health and Social Care; 2021 Jan 9 \[cited 2025 Sep 05].
Available from: www.gov.uk
| Rationale for the Project | Project Objectives |
| Submission and Reporting Mechanism for Clinicians | Team Structure |