Meningioma Diagnoses Nearly Doubled in Denmark Over 14 Years — But Most Surveillance Scans Never Led to Treatment

Why This Study Matters

Meningiomas are the most common tumor of the central nervous system, and most are now discovered incidentally as neuroimaging use has expanded. Because the majority are indolent, clinicians typically manage them with serial MRI surveillance rather than immediate treatment — but that guidance rests largely on expert consensus rather than outcome data. The result may be a growing mismatch between how much imaging is performed and how often that imaging actually changes management.

This nationwide Danish study set out to quantify that mismatch directly: how meningioma incidence has changed over 14 years, whether treatment has kept pace, and how much of the surveillance imaging burden is actually converting into a treatment decision.

Study Design

This was a retrospective, nationwide quality-improvement study — not a randomized clinical trial — built on linked Danish national registries: the Danish Neuro-Oncology Registry, the Danish National Patient Registry, the Danish Pathology Registry, and the Danish Civil Registration System. Data were extracted April 11, 2025, and reported according to the STROBE and SQUIRE guidelines. Because every Danish resident is tracked through a unique civil registration number, the authors were able to link diagnosis, treatment, and imaging records for every meningioma patient in the country over a 14-year window.

Primary outcomes: trends in meningioma incidence, treatment conversion (surgery or radiotherapy), and volume of surveillance imaging (MRI/CT) from 2010 through 2023. Secondary outcomes: intervention timing and imaging use after final treatment.

Patient Population

The study included all adults (age 18 or older) diagnosed with meningioma in Denmark between January 1, 2010, and December 31, 2023, identified through WHO ICD-10 codes. Of 8,412 patients initially identified, 278 were excluded (age under 18, unknown region of residence, or unverified histopathology for surgical patients), leaving 8,134 patients for analysis.

Median age at diagnosis was 66 years (range, 18-102). The cohort skewed heavily female: 6,002 patients (73.8%) were women and 2,132 (26.2%) were men, a female-to-male ratio of 2.8 (95% CI, 2.7-3.0). Most patients were relatively healthy at baseline — 58.0% had a Charlson Comorbidity Index score of 0.

Primary Endpoint Results

The headline finding is a divergence between diagnosis and treatment. Incidence nearly doubled over the study period, rising from 6.4 to 12.6 cases per 100,000 person-years — a mean annual increase of 4.2% (95% CI, 3.6%-4.8%; P < .001) — while the absolute number of surgeries and radiotherapy courses performed each year stayed essentially flat. That combination mechanically drove down the proportion of diagnosed patients who ultimately received treatment.

Surgery was the dominant intervention: 2,665 patients (32.8%) underwent one or more procedures, the large majority (2,657 of 2,665) via resection rather than biopsy alone. Among surgically treated patients, pathology confirmed WHO grade 1 (benign) tumors in 2,379 (89.3%), grade 2 in 261 (9.8%), and grade 3 in 25 (0.9%). Radiotherapy was less common, used in 439 patients (5.4%) — 277 combined with surgery and 162 as a stand-alone treatment.

Despite the increasing meningioma incidence over time, the number of yearly surgeries remained stable.
— Results, Surgery section, Trends in Meningioma Incidence, Treatment, and Imaging Surveillance, JAMA Oncology (2026)

The clearest sign of surveillance overuse: 84.5% of first surgeries happened within a year of diagnosis, and the likelihood of surgery after year 5 was minimal — just 1.4% of previously untreated patients (78 of 5,547) went on to surgery beyond that point.

Subgroup Analyses

Two of the three subgroup observations above are reported qualitatively in the source text without an accompanying exact rate, hazard ratio, or confidence interval — they are presented here exactly as described, without inventing a number to fill the gap.

Safety Profile

This study did not evaluate treatment safety or adverse events in the conventional clinical-trial sense — it is an observational analysis of diagnostic and treatment patterns, not an interventional safety study. The relevant burden the authors highlight instead is imaging volume: of 28,736 total MRI scans performed during the study period, 23,992 (83.5%) were not followed by treatment, and 49.6% of all scans were performed in patients who never received any treatment at all. The authors frame this volume of non-actionable imaging as carrying its own costs — financial, logistical, and psychological — for patients undergoing years of surveillance for a tumor that, in most cases, will never require intervention.

Interpretation and Broader Context

The authors situate their findings alongside data from the Central Brain Tumor Registry of the United States and prior Scandinavian registry studies, both of which have also documented rising meningioma incidence attributed largely to expanded imaging access and an aging population. Consistent with earlier Scandinavian work by Näslund and colleagues, most newly diagnosed meningiomas in this cohort were incidental and managed conservatively — reinforcing the authors' concern about overdiagnosis and unnecessarily intensive follow-up imaging.

The clinical response has already begun: the findings directly informed a 2026 revision of Danish national meningioma surveillance guidelines, moving to an age-based, risk-adapted imaging schedule. Under the new regimen, patients younger than 50 receive MRI or CT at 1, 5, and 10 years (discontinued if stable); patients 50-70 are imaged at 1 and 5 years; patients 71-80 are imaged once, at 1 year; and patients over 80 are imaged only if clinically indicated. The authors estimate this could reduce MRI volume by 60%-70% among the roughly 70% of patients who do not require immediate treatment.

Limitations

The authors note several limitations specific to this study. Follow-up was capped at 10-14 years, so very late tumor progression — meningiomas can recur decades after diagnosis — may be underrepresented, and the findings should not be read as license for universal discontinuation of long-term surveillance. Generalizability is also uncertain outside Denmark's tax-funded, universally accessible health system and comparatively homogeneous population. The study also does not capture stereotactic radiosurgery, which is not used in Denmark but is common elsewhere, so the treatment-conversion figures may not generalize to health systems where that option is offered. Two of the reported subgroup comparisons (surgery by age and incidence rise by age group) are stated qualitatively in the source without an exact effect size, limiting how precisely those patterns can be characterized.

Funding & Disclosures

The source publication does not include a formal funding or sponsor statement; the analysis draws on Danish national health registries. This is an observational registry study and carries no ClinicalTrials.gov identifier.

What's Next

The authors call for prospective validation of risk-stratification tools such as the IMPACT score, MRI-based radiomics, and molecular profiling (including 1p/22q deletion, CDKN2A/B deletion, and TERT promoter mutation status), along with further evaluation of investigational 18F-fluorothymidine PET imaging as a noninvasive marker of tumor proliferation. They also recommend formal health-economic assessment of risk-adapted surveillance protocols before broader international adoption.