Emerging research suggests that positron emission tomography/computed tomography (PET/CT) may be significantly more effective than magnetic resonance imaging (MRI) and CT at diagnosing lymph node metastasis in patients with early-stage cervical cancer.
Utilizing 2009-2017 data from the Netherlands Cancer Registry for the retrospective study (recently published in Insights into Imaging), researchers reviewed lymph node assessment findings with MRI in 1,676 patients, CT in 926 patients and 18F FDG PET-CT in 379 patients.
For overall accuracy in diagnosing lymph node metastases in this patient population, the study authors found that 18F FDG PET-CT had an 80 percent sensitivity rate in comparison to 48 percent for MRI and 40 percent for CT.
The researchers pointed out that the specificity rate for 18F FDG PET-CT was 13 percent lower (79 percent) than MRI and CT (92 percent for both). However, they also noted that 18F FDG PET-CT had the highest area under the curve (AUC) at 81.4 percent in contrast to 70.6 percent for MRI and 66.7 percent for CT. The study authors also acknowledged that 18F FDG PET-CT was utilized to confirm MRI and CT results for 95 percent of patients.
“Verification of MRI/CT results with 18F FDG-PET-CT seems useful to identify patients at high risk of metastasis, particularly in cases with suspicious nodes on MRI. Our results suggest that this strategy reduces the risk of unwarranted omission of surgery or, in (the) case of primary chemoradiotherapy, overtreatment with nodal boosting/extended field (fewer false positives),” wrote lead study author Ester P. Olthof, M.D., who is affiliated with the Department of Research and Development at the Netherlands Comprehensive Cancer Organization in Utrecht and the Department of Gynecological Oncology at Amsterdam University Medical Center in Amsterdam, the Netherlands, and colleagues.
The study authors emphasized the critical nature of lymph node status accuracy on the management of patients with early-stage cervical cancer.
“In early-stage cervical cancer, the nodal status determines whether radical hysterectomy or (chemo)radiotherapy is recommended,” maintained Olthof and colleagues. “In (chemo)radiotherapy, suspicious nodes on imaging may influence radiotherapy settings (i.e. extended-field and nodal boosting).”
Three Key Takeaways
- PET/CT's higher sensitivity in diagnosing lymph node metastasis. The study suggests that 18F FDG PET-CT is significantly more effective than MRI and CT in diagnosing lymph node metastasis in early-stage cervical cancer patients. PET/CT exhibited an 80 percent sensitivity rate, compared to 48 percent for MRI and 40 percent for CT.
- Importance of PET/CT verification in high-risk cases. The researchers highlight the utility of using 18F FDG PET-CT to confirm MRI and CT results, particularly in cases with suspicious nodes on MRI. The verification strategy is deemed useful in identifying patients at high risk of metastasis, reducing the risk of unnecessary omission of surgery or overtreatment with nodal boosting/extended field, thereby facilitating optimal treatment decisions.
- Regional variation in accuracy. While PET/CT demonstrated higher sensitivity and area under the curve (AUC) than MRI and CT in the pelvic region, it showed lower sensitivity rates in the common iliac region. This regional variation is a pertinent consideration for clinicians in selecting the most appropriate imaging modality when evaluating nodal status in patients with cervical cancer.
For region-based accuracy, 18F FDG PET-CT demonstrated a higher AUC than MRI and CT (80.3 percent vs. 70.5 percent and 65.6 percent) and superior sensitivity (77 percent vs. 47 percent and 37 percent) for detection of nodal metastases in the pelvic region.
However, in the common iliac region, the study authors noted lower sensitivity rates for 18F FDG PET-CT, MRI and CT (19 percent vs. 10 percent and 0 percent) as well as lower AUCs (58.2 percent vs. 54.9 percent and 49.7 percent). The researchers also pointed out higher specificity rates for the three imaging modalities (98 percent vs. 99 percent for MRI and CT) in comparison to specificity rates for the overall pelvic region.
(Editor’s note: For related content, see “FDA Clears AI-Powered Digital Cytology Platform for Cervical Cancer,” “Image IQ Quiz: 30-Year-Old Female with Lower Abdominal and Pelvic Fullness and Abnormal Menstrual Cycles” and “Cancer Screenings and COVID-19: What a New Study Shows.”)
In regard to study limitations, the researchers noted the recording of patient nodal status drawn from different facilities over an eight-year period may have led to intra- and inter-observer variability that could have affected study results. Given the study period between 2009 and 2017, the authors acknowledged the findings were primarily based on conventional imaging modalities and suggested that modalities such as diffusion-weighted (DW) MRI could have increased the sensitivity rate.
