Clinical significance of MRI-based tumor status differs by histological subtype in early-stage cervical cancer

To determine whether Magnetic Resonance Imaging (MRI) findings reflect pathological risk factors in early-stage cervical cancer and whether its clinical significance differs by histological subtype.

This multicenter retrospective study included patients with FIGO 2009 stage ≤ IB1 cervical cancer who underwent preoperative MRI. Maximal tumor diameter (MRI(L)) and perpendicular short diameter (MRI(D)) were categorized at 10-mm intervals. Associations with pathological low-risk criteria (tumor length ≤ 20 mm, invasion depth ≤ 10 mm, and their combination [S-criteria]) and lymphovascular space invasion (LVSI) were analyzed for squamous cell carcinoma (SCC) and HPV-associated adenocarcinoma (HPVA-adenocarcinoma) using the Cochran-Armitage trend test, with interobserver agreement assessed using weighted kappa statistics.

The study included 246 SCC and 93 HPVA-adeno cases. MRI categorization showed substantial interobserver agreement (κ = 0.87-0.97). The S-criteria threshold differed by subtype: in SCC, the proportion meeting S-criteria fell to 58.6 % in the MRI(L) 10-20 mm category, versus 83.3 % in HPVA-adeno. LVSI positivity also increased significantly with MRI category in both subtypes (p < 0.0001 and p = 0.006), with distinct patterns: in SCC, LVSI rose sharply once MRI(L) reached 10 mm (14.8 % vs. 56.5 %); in HPVA-adeno, LVSI was rare among MRI-invisible tumors (2.7 %) but present in 33.3 % of visible tumors < 10 mm. This histology-specific pattern was confirmed by a formal interaction test for LVSI (p = 0.024).

The clinical significance of MRI findings differs by histological subtype in early-stage cervical cancer: MRI size categories reliably reflect pathological risk in SCC, whereas MRI size alone is insufficient for risk stratification in early-stage HPVA-adenocarcinoma.