Abstract
Aim To investigate the role of maximum tumour diameter (D-max) reduction rate at CT examination in predicting histopathological tumour regression grade (TRG according to the Becker grade), after neoadjuvant chemotherapy (NAC), in patients with resectable advanced gastric cancer (AGC). Materials and Methods Eighty-six patients (53 M, mean age 62.1 years) with resectable AGC (≥T3 or N+), treated with NAC and radical surgery, were enrolled from 5 centres of the Italian Research Group for Gastric Cancer (GIRCG). Staging and restaging CT and histological results were retrospectively reviewed. CT examinations were contrast enhanced, and the stomach was previously distended. The D-max was measured using 2D software and compared with Becker TRG. Statistical data were obtained using “R” software. Results The interobserver agreement was good/very good. Becker TRG was predicted by CT with a sensitivity and specificity, respectively, of 97.3% and 90.9% for Becker 1 (D-max reduction rate > 65.1%), 76.4% and 80% for Becker 3 (D-max reduction rate < 29.9%), and 70.8% and 83.9% for Becker 2. Correlation between radiological and histological D-max measurements was strongly confirmed by the correlation index (c.i.= 0.829). Conclusions D-max reduction rate in AGC patients may be helpful as a simple and reproducible radiological index in predicting TRG after NAC.
Highlights
In the Western world, almost two-thirds of patients with gastric cancer (GC) have locally advanced tumours at the time of diagnosis with a less than 50% chance of radical surgery [1, 2]
D-max from staging and restaging CT scans (CTs) examinations did not demonstrate a normal distribution at the Shapiro-Wilk test (p < 0 05) as reported in QQ plots (Figures 2 and 3) in order to avoid statistical errors, mean value distribution was calculated through the bootstrap method resulting in 100.4 mm before and 68.4 mm after neoadjuvant chemotherapy (NAC), respectively
D-max box plots graphically showed a difference between the 2 groups, before and after NAC (Figure 4), which was confirmed applying the Wilcoxon test for paired samples (p = 1938 e-06, statistically significant), demonstrating that chemotherapy induced a reduction in CT-measured D-max
Summary
In the Western world, almost two-thirds of patients with gastric cancer (GC) have locally advanced tumours (stage IIIA or B, or IV) at the time of diagnosis with a less than 50% chance of radical surgery [1, 2]. Even if long-term outcomes of patients with advanced gastric cancer (AGC) remain poor despite multimodality treatment [6, 7], patients with clinical response to NAC have a significantly better prognosis than nonresponding patients For this reason, preoperative identification of responder patients, as well as methods for predicting the outcome of patients submitted to NAC, is crucial in order to provide prognostic information to patients and guide clinicians in further surgical and/or adjuvant treatments [8, 9]. Emerging imaging methodologies for achieving this goal are not always reproducible and easy to use [8, 16,17,18,19]
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