ULTRASOUND achieved diagnostic accuracy comparable to PET/CT and diffusion-weighted MRI (DW-MRI) for preoperative pelvic lymph node assessment in cervical cancer, according to findings from the CANNES trial.
The study, conducted across three European gynaecological oncology centres, found that ultrasound met predefined non-inferiority criteria versus both PET/CT and DW-MRI for detecting pelvic lymph node metastases before surgery. Pelvic lymph node status is a key factor in treatment planning, helping guide decisions on surgery and other therapeutic approaches.
Ultrasound Shows Comparable Accuracy to PET/CT and DW-MRI
Between January 2021 and December 2023, investigators enrolled women with histopathologically confirmed cervical cancer ranging from International Federation of Gynecology and Obstetrics (FIGO) Stage IA1 with lymphovascular space invasion to Stage IIIC2. A total of 120 patients were included in the analysis.
All participants underwent ultrasound and PET/CT, while 108 also received DW-MRI before surgery. Imaging findings were compared against final histopathology, the study’s primary reference standard.
Among the analysed cohort, 29 patients had pelvic lymph node macrometastases confirmed on histopathology. Overall nodal involvement, including micro- and macrometastases, was ultimately identified in 38 patients.
For detection of pelvic lymph node macrometastases, ultrasound achieved a sensitivity of 79.3%, specificity of 87.9% and diagnostic accuracy of 85.8%. Corresponding values were 75.9%, 86.8% and 84.2% for PET/CT, and 70.8%, 90.5% and 86.1% for DW-MRI.
When both micro- and macrometastases were included, diagnostic accuracy reached 83.3% for ultrasound, compared with 81.7% for PET/CT and 87.0% for DW-MRI.
Why Pelvic Lymph Node Assessment Remains Challenging
The investigators noted that small metastatic deposits frequently remain below the detection threshold of current imaging technologies. Micrometastases may not sufficiently alter lymph node structure, metabolic activity or diffusion characteristics to be identified reliably on imaging.
Therefore, the findings reinforce that imaging alone cannot replace surgical nodal staging when low-volume disease is suspected. Sentinel lymph node biopsy with ultrastaging remains necessary for detecting micrometastatic disease.
Expert Training May Determine Wider Adoption
The study was designed to minimise bias through independent image interpretation and blinding between modalities. However, ultrasound examinations were performed by highly trained gynaecological oncology sonographers, and no formal interobserver reproducibility analysis was undertaken.
Investigators cautioned that the reported performance reflects outcomes achievable in specialised, high-volume centres. Broader implementation may depend on standardised training, certification pathways and adherence to established imaging protocols.
Nevertheless, as the first prospective multicentre trial to directly compare ultrasound, PET/CT and DW-MRI for pelvic nodal assessment, the study provides evidence that ultrasound can deliver comparable diagnostic performance. Given its wider availability, it may offer a practical alternative for preoperative pelvic lymph-node assessment in settings where access to PET/CT or DW-MRI is limited.
Reference
Frühauf F et al. Prospective comparison of diagnostic accuracy of ultrasound, PET/CT and DW-MRI for preoperative assessment of pelvic lymph nodes in cervical cancer patients: results of the CANNES trial. Ultrasound Obstet Gynecol. 2026;67(6):836-851.
Featured image: MdBabul on Adobe Stock
