Diagnostic accuracy of tests for lymph node status in primary cervical cancer: a systematic review and meta-analysis

Abstract

Background: Lymph node status is the key to determining the prognosis and treatment of cervical cancer. However, it cannot be assessed clinically, and testing for nodal metastasis is controversial. We sought to systematically review the diagnostic accuracy literature on sentinel node biopsy, positron emission tomography, magnetic resonance imaging and computed tomography to evaluate the accuracy of each index test in determining lymph node status in patients with cervical cancer.

Methods: We searched MEDLINE (1966-2006), EMBASE (1980-2006), Medion (1980-2006) and the Cochrane library (Issue 2, 2006) for relevant articles. We also manually searched the reference lists from primary articles and reviews, and we contacted experts in the field for conference abstracts and unpublished studies. We performed random-effects meta-analysis of accuracy indices, and we performed meta-regression analysis to test the effect of study quality on diagnostic accuracy and to identify other sources of heterogeneity.

Results: We included 72 relevant primary studies, involving a total of 5042 women, in our analysis. We found that, in determining lymph node status, sentinel node biopsy had a pooled positive likelihood ratio of 40.8 (95% confidence interval [CI] 24.6-67.6) and a pooled negative likelihood ratio of 0.18 (95% CI 0.14-0.24). The pooled positive likelihood ratios (and 95% CI) were 15.3 (7.9-29.6) for positron emission tomography, 6.4 (4.9-8.3) for magnetic resonance imaging and 4.3 (3.0-6.2) for computed tomography. The pooled negative likelihood ratios (and 95% CIs) were 0.27 (0.11-0.66) for positron emission tomography, 0.50 (0.39-0.64) for magnetic resonance imaging and 0.58 (0.48-0.70) for computed tomography. Using a 27% pretest probability of lymph node metastasis among all cases (regardless of stage), we found that a positive sentinel node biopsy result increased post-test probability to 94% (95% CI 90%-96%), whereas a positive finding on positron emission tomography increased it to 85% (75%-92%).

Interpretation: Sentinel node biopsy has greater accuracy in determining lymph node status among women with primary cervical cancer than current commonly used imaging methods.

Figure 1: Search and selection of studies for systematic review. *Some studies reported on more than one index test.

Figure 2: Bivariable analysis of the accuracy of sentinel node biopsy, positron emission tomography, magnetic resonance imaging and computed tomography in determining lymph node status in patients with cervical cancer. The bivariable analysis produces mean estimates of sensitivity and specificity along with the 95% confidence intervals of each index test. Each ellipsis represents the region containing likely combinations of the mean value of sensitivity and specificity. The closer the index values are to the upper-left corner, the greater the accuracy of that index test. Note: the x axis shows reversed specificity.