Clinical Research Papers:
Extramural depth of rectal cancer tumor invasion at thin-section MRI: predicting treatment response to neoadjuvant chemoradiation
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Tong Tong1,*, Yiqun Sun1,*, Sanjun Cai2, Zhen Zhang3, Yajia Gu1
1Department of Radiology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
2Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
3Department of Radiotherapy, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
*These authors have contributed equally to this work
Yajia Gu, e-mail: firstname.lastname@example.org
Zhen Zhang, e-mail: email@example.com
Keywords: MRI, depth of invasion, rectal cancer, neoadjuvant therapy
Received: May 18, 2015 Accepted: July 27, 2015 Published: August 06, 2015
Objectives: To assess whether the maximal extramural depth (EMD) of T3 tumor spread on magnetic resonance imaging(MRI) correlates with tumor response parameters and whether it can predict tumor response to neoadjuvant chemoradiation.
Methods: 111 rectal cancer patients with American Joint Committee on Cancer (AJCC) T3 tumors underwent MRI staging before neoadjuvant chemoradiotherapy were included. Tumor EMD was measured as mm tumor beyond the muscular and compared between the following groups by Kruskal-Wallis test: pathological complete response(pCR) versus nonpCR, good regression versus poor regression, downstage versus nondownstage.
Results: The final study population consisted of the 111 patients (79 male, 32 female). Median age was 56 years (range, 23–75 years). The EMD was significantly higher in nonpCR patients (7.8 ± 3.2 mm) than in pCR patients(6.1 ± 1.8 mm) (p = 0.033). According to good regression (tumor regression grade(TRG) 0–1 vs. TRG 2–3) and downstaging (ypStage 0-I vs. ypStage II–III), the difference was not significant. Receiver operating characteristic curve analysis revealed a good value for the area under the curve (0.775) and the cutoff value for EMD to predict pCR was 5.6 mm. Compared with patients with a EMD ≥ 5 mm, more patients with EMD <5 mm showed pCR (p = 0.019), while there was no correlation between EMD and good regression or downstaged.
Conclusion: EMD value obtained on initial staging MRI may serve as an imaging biomarker which predicts patients that have an incomplete response pathological response after standard neoadjuvant therapy.
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