1 research outputs found
Prediction of N0 Irradiated Rectal Cancer Comparing MRI Before and After Preoperative Chemoradiotherapy
BACKGROUND: The prediction of lymph node status using MRI has an impact on the
management of rectal cancer, both before and after preoperative chemoradiotherapy.
OBJECTIVE: To maximize the negative predictive value and sensitivity of mesorectal
lymph node imaging after chemoradiotherapy because post-chemoradiation nodenegative
patients may be treated with rectum-sparing approaches.
DESIGN: Retrospective study.
SETTINGS: The study was conducted at a tertiary-care hospital.
PATIENTS: Sixty-four patients with locally advanced rectal cancer who underwent
preoperative chemoradiotherapy and MRI for staging and the assessment of response
were evaluated.
MAIN OUTCOME MEASURES: The sums of the sizes of all mesorectal lymph nodes
in each patient on both pre- and post-chemoradiotherapy imaging datasets were
calculated to determine the lymph node global size reduction rates, taking these to be
the outcomes of the histopathologic findings. Other included measures were interobserver
agreement regarding the prediction of node status based on morphologic
criteria and the diagnostic performance of contrast-enhanced images.
RESULTS: Using a cutoff value of a 70% lymph node global size reduction rate with
only 15 node-positive patients on histopathology, the sensitivity in the prediction of
nodal status and negative predictive value were 93% (95%CI: 70.2-98.8) and 97%
(95%CI: 82.9-99.8) for Observer 1, and 100% (95%CI: 79.6-100) and 100 % (95%CI:62.9-100) for Observer 2. The areas under the receiver operating characteristic curves
for the two observers were 0.90 (95%CI: 0.82-0.98, p<0.0001) for Observer 1 and 0.65
(95%CI: 0.50-0.79, p=0.08) for Observer 2. The efficacy of the morphologic criteria and
contrast-enhanced images in predicting node status was limited after
chemoradiotherapy.
LIMITATIONS: This study is limited by its small sample size and retrospective nature.
CONCLUSIONS: Assessing the lymph node global size reduction rate value reduces
the risk of undetected nodal metastases and may be helpful in better identifying
suitable candidates for the local excision of early-stage rectal cancer