Neoadjuvant chemotherapy (NCT) has been successfully introduced in the management of gastrointestinal malignancies. It is recommended because of its potential benefits: downstaging of the primary tumor and lymph nodes [
Increasingly, the assessment of the effect of NCT becomes important. Tumor regression grade (TRG) is a system to evaluate the amount of residual tumor in patients who underwent preoperative therapy. Different from TNM stage, the TRG score focuses on the quantity rather than the location of the remain tumor, which could provide extra information on the response of tumor to the treatment and assist in predicting the prognosis [
There are many different grading systems without a global consensus [
In addition, in some cases, although TRG showed prognostic significance in univariable analysis, its prognostic worth was lost in multivariable analysis [
The purpose of this study is to validate the significance of the Mandard TRG system in locally advanced gastric adenocarcinoma patients, who undergone neoadjuvant chemotherapy and curative surgery based on our database, and explore if the significance of TRG would change in patients with different status of lymph node.
Patients with locally advanced gastric adenocarcinoma (including esophagogastric junction carcinoma) who underwent neoadjuvant chemotherapy in our institute between July 2010 and June 2016 were identified from the electronic database of our hospital. The eligibility criteria of our study included the following: (1) histopathological evidence of gastric adenocarcinoma; (2) locally advanced gastric cancer (8th AJCC clinical stage: cT2N1M0~T4N3M0, II~III); (3) underwent neoadjuvant chemotherapy with or without postoperative treatment; (4) curative gastrectomy surgery was performed; and (5) age ranged from 20 to 80 years old. Exclusion criteria were as follows: (1) underwent preoperative radiotherapy; (2) suffering from other malignant tumor or gastric remnant cancer; and (3) incomplete information on staging or therapy.
All the slides or blocks of surgical specimens were retrieved from the biospecimen library of our hospital and were reevaluated by two experienced gastrointestinal pathologists (YM.Z and D.L), respectively. The TNM stage was evaluated according to the 8thedition of the AJCC cancer staging. Histological regression grade of the primary tumor was assessed in accordance with the Mandard criteria: TRG 1 (fibrosis with no evidence of residual tumor, i.e., complete regression), TRG 2 (fibrosis with single cells or rare groups of residual tumor cells), TRG 3 (fibrosis and residual tumor with a dominance of fibrosis), TRG 4 (fibrosis and residual tumor with a dominance of tumor), and TRG 5 (extensive tumor without evidence of regression). When disagreement between pathologists appeared, a consensus would be reached by joint re-review and discussion through a multihead microscope. Other extracted histopathologic characteristics were reconfirmed during the assessment process.
Survival curves for overall survival (OS) and disease-free survival (DFS) were obtained using the Kaplan–Meier method, and the log-rank test was used to compare survival differences. The Cox regression analysis was used to assess the prognostic risk of clinicopathological characteristics on OS and DFS, and the factors with
From 3196 patients, 290 matched the criteria of our study, and their baseline characteristics are listed in Table
Clinicopathological characteristics.
Characteristics | No. of patients | Percent |
---|---|---|
Gender | ||
Male | 215 | 74.1 |
Female | 75 | 25.9 |
Age | ||
<65 | 221 | 76.2 |
≥65 | 69 | 23.8 |
Tumor location | ||
L | 172 | 59.3 |
M | 54 | 18.6 |
U | 32 | 11.0 |
GEJ | 8 | 2.8 |
Diffuse | 24 | 8.3 |
Tumor size (cm) | ||
<5 | 115 | 39.7 |
≥5 | 175 | 60.3 |
ypT | ||
0 | 9 | 3.1 |
1-2 | 57 | 19.6 |
3-4 | 224 | 77.3 |
ypN | ||
0 | 100 | 34.5 |
1 | 49 | 16.9 |
2 | 79 | 27.2 |
3 | 62 | 21.4 |
ypTNM | ||
I | 52 | 17.9 |
II | 71 | 24.5 |
III | 167 | 57.6 |
Histological type | ||
Adenocarcinoma | 186 | 64.1 |
Mucinous or signet ring cell carcinoma | 104 | 35.9 |
Lauren classification | ||
Intestinal | 143 | 49.3 |
Diffuse or mixed | 147 | 50.7 |
Grade of differentiation | ||
Well | 70 | 25.2 |
Moderate or poor | 220 | 74.8 |
Vascular or lymphatic invasion | ||
No | 218 | 75.2 |
Yes | 72 | 24.8 |
Nervous invasion | ||
No | 222 | 76.6 |
Yes | 68 | 23.4 |
Mandard TRG | ||
1 | 9 | 3.1 |
2 | 84 | 29.0 |
3 | 90 | 31.0 |
4 | 85 | 29.3 |
5 | 22 | 7.6 |
Neoadjuvant therapy | ||
SOX | 214 | 73.8 |
XELOX | 21 | 7.2 |
FOLFOX | 55 | 19.0 |
Adjuvant treatment | ||
No | 31 | 10.7 |
Yes | 259 | 89.3 |
The median number of reviewed slides indicating surgical specimen was 4 with an interquartile range from 3 to 5. After reevaluation, 9 patients had no residual tumor (ypT0). In 57 patients (19.6%), residual tumors did not extend beyond the muscular layer (ypT1-2). In 224 patients (77.3%), residual tumors reached or exceeded the subserosal layer (ypT3-4). 143 patients were intestinal classification (49.3%), while only 70 patients were well differentiated (25.2%). Vascular or lymphatic invasion (VOLI) was found in 72 patients (24.8%), while nervous invasion (NI) in 68 patients (23.4%).
As for tumor regression grade, the example of every grade of Mandard TRG is shown in Figure
Examples of Mandard TRG. (a) Complete tumor regression, TRG 1. (b) Rare residual tumor, TRG 2. (c) More residual tumor but less than fibrosis, TRG 3. (d) Residual tumor with signs of regression, TRG 4. (e) Residual tumor without regression, TRG 5.
The average number of lymph node removed was 28, with an interquartile range from 19 to 33. 100 patients had no lymph node metastasis (ypN-). 190 patients had at least one lymph node metastasis (ypN+), with the average number of positive nodes being 7.
The median follow-up for all patients was 41 months, with an interquartile range of 21 to 55 months. No significant difference in OS (
For 93 patients with TRG 1-2, the median OS and DFS were 52 and 50 months, respectively. For 197 patients in TRG 3-5 team, the median OS and DFS were 35 and 24 months, respectively. In univariable analysis, patients with TRG 1-2 owned better OS (
Univariate analysis of clinicopathological factors.
Prognostic factors | OS | DFS | ||
---|---|---|---|---|
Hazard ratio (95% CI) | Hazard ratio (95% CI) | |||
Gender | 1.298 (0.896, 1.882) | 0.168 | 1.218 (0.854, 1.737) | 0.276 |
Age | 1.572 (1.084, 2.260) | 0.017 | 1.445 (1.013, 2.062) | 0.042 |
Tumor location | 0.001 | 0.001 | ||
L | 1 | 1 | ||
M | 0.727 (0.443, 1.191) | 0.206 | 0.683 (0.424, 1.102) | 0.118 |
U | 1.098 (0.620, 1.945) | 0.748 | 0.921 (0.523, 1.621) | 0.776 |
GEJ | 2.262 (1.041, 4.915) | 0.039 | 2.251 (1.089, 4.653) | 0.028 |
Diffuse | 2.537 (1.511, 4.259) | 0.001 | 2.636 (1.612, 4.309) | 0.001 |
Tumor size (cm) | 2.647 (1.784, 3.928) | 0.001 | 2.198 (1.535, 3.148) | 0.001 |
ypT | 0.001 | 0.001 | ||
0 | 1 | 1 | ||
1-2 | 1.968 (0.252, 15.379) | 0.519 | 2.463 (0.322, 18.829) | 0.385 |
3-4 | 8.166 (1.140, 58.501) | 0.001 | 8.953 (1.251, 64.084) | 0.029 |
ypN | 0.001 | 0.001 | ||
0 | 1 | 1 | ||
1 | 5.398 (2.860, 10.187) | 0.001 | 3.338 (1.868, 5.966) | 0.001 |
2 | 5.284 (2.873, 9.718) | 0.001 | 4.291 (2.570, 7.165) | 0.001 |
3 | 13.507 (7.383, 24.711) | 0.001 | 9.483 (5.662, 15.884) | 0.001 |
ypTNM | ||||
I-II vs. III | 9.214 (1.161, 73.009) | 0.036 | 4.480 (3.005, 6.678) | 0.001 |
Histological type | 1.576 (1.117, 2.222) | 0.010 | 1.471 (1.060, 2.041) | 0.021 |
Lauren classification | 2.223 (1.557, 3.174) | 0.001 | 2.136 (1.528, 2.987) | 0.001 |
Grade of differentiation | 3.521 (2.023, 6.129) | 0.001 | 3.315 (1.999, 5.498) | 0.001 |
Vascular or lymphatic invasion | 2.242 (1.568, 3.204) | 0.001 | 2.133 (1.513, 3.005) | 0.001 |
Nervous invasion | 1.652 (1.142, 2.390) | 0.008 | 1.610 (1.131, 2.291) | 0.008 |
Mandard TRG | ||||
1-2 vs. 3-5 | 3.822 (2.371, 6.162) | 0.001 | 3.374 (2.190, 5.200) | 0.001 |
Neoadjuvant therapy | 0.344 | 0.627 | ||
FOLFOX | 1 | 1 | ||
SOX | 0.895 (0.594, 1.350) | 0.597 | 0.855 (0.576, 1.269) | 0.436 |
XELOX | 0.520 (0.216, 1.250) | 0.144 | 0.728 (0.347, 1.526) | 0.400 |
Adjuvant treatment | 1.659 (0.996, 2.763) | 0.052 | 1.790 (1.117, 2.871) | 0.016 |
Multivariate analysis of prognostic factors.
Prognostic factors | OS | DFS | ||
---|---|---|---|---|
Hazard ratio (95% CI) | Hazard ratio (95% CI) | |||
Age | 1.713 (1.154, 2.543) | 0.008 | 1.474 (1.014, 2.145) | 0.042 |
Tumor location | 0.053 | 0.022 | ||
L | 1 | 1 | ||
M | 0.669 (0.392, 1.143) | 0.141 | 0.617 (0.369, 1.032) | 0.066 |
U | 1.526 (0.823, 2.832) | 0.180 | 1.148 (0.630, 2.093) | 0.652 |
GEJ | 1.100 (0.491, 2.465) | 0.818 | 1.192 (0.564, 2.519) | 0.645 |
Diffuse | 1.759 (0.993, 3.118) | 0.053 | 1.919 (1.117, 3.297) | 0.018 |
Tumor size (cm) | 1.772 (1.102, 2.849) | 0.018 | 1.556 (0.996, 2.430) | 0.052 |
ypT | 0.644 | 0.438 | ||
0 | 1 | 1 | ||
1-2 | 1.204 (0.138, 10.500) | 0.867 | 1.384 (0.167, 11.434) | 0.763 |
3-4 | 1.954 (0.212, 17.971) | 0.554 | 2.340 (0.281, 19.514) | 0.432 |
ypN | 0.005 | 0.011 | ||
0 | 1 | 1 | ||
1 | 5.104 (1.733, 15.027) | 0.003 | 3.317 (1.345, 8.184) | 0.009 |
2 | 4.882 (1.618, 14.730) | 0.005 | 3.600 (1.426, 9.088) | 0.007 |
3 | 7.641 (2.404, 24.283) | 0.001 | 5.200 (1.949, 13.869) | 0.001 |
ypTNM | 0.842 (0.266, 2.663) | 0.769 | 0.747 (0.283, 1.974) | 0.557 |
Histological type | 0.934 (0.631, 1.382) | 0.731 | 0.879 (0.605, 1.276) | 0.498 |
Lauren classification | 1.433 (0.942, 2.181) | 0.093 | 1.334 (0.900, 1.979) | 0.152 |
Grade of differentiation | 1.620 (0.849, 3.093) | 0.143 | 1.666 (0.915, 3.032) | 0.095 |
Vascular or lymphatic invasion | 1.739 (1.166, 2.592) | 0.007 | 1.465 (1.002, 2.144) | 0.049 |
Nervous invasion | 0.966 (0.645, 1.447) | 0.866 | 0.981 (0.668, 1.441) | 0.924 |
Mandard TRG | 1.429 (0.797, 2.561) | 0.231 | 1.430 (0.836, 2.443) | 0.191 |
Adjuvant treatment | 2.556 (1.486, 4.396) | 0.001 | 2.556 (1.531, 4.270) | 0.001 |
In addition, the lymph node metastasis stage owned the highest hazard ratio among the independent prognostic factors for OS (all
Because of the metastasis of lymph node possessing great impact on survival, which might influence the effect of TRG on prognosis, the stratified analysis by lymph node metastasis was performed.
In the analysis of ypN- patients, survival curves showed TRG was not related to OS (
The Kaplan–Meier curves of grouped TRG stratified by ypN status. TRG lost predicting significance for OS (a) and DFS (b) in ypN- patients, while retrieved predicting significance for OS (c) and DFS (d) in ypN+ patients.
Multivariate analysis of patients with lymph node metastasis.
Prognostic factors | OS | DFS | ||
---|---|---|---|---|
Hazard ratio (95% CI) | Hazard ratio (95% CI) | |||
Age | 1.815 (1.197, 2.752) | 0.005 | 1.396 (0.932, 2.091) | 0.105 |
Tumor location | 0.128 | 0.053 | ||
L | 1 | 1 | ||
M | 0.626 (0.358, 1.094) | 0.100 | 0.597 (0.342, 1.040) | 0.068 |
U | 1.196 (0.593, 2.413) | 0.618 | 1.057 (0.532, 2.100) | 0.873 |
GEJ | 1.139 (0.511, 2.539) | 0.750 | 1.260 (0.599, 2.651) | 0.542 |
Diffuse | 1.676 (0.932, 3.014) | 0.085 | 1.809 (1.029, 3.012) | 0.040 |
Tumor size (cm) | 2.093 (1.276, 3.431) | 0.003 | 1.864 (1.153, 3.012) | 0.011 |
ypT | 0.693 | 0.458 | ||
0 | 1 | 1 | ||
1-2 | 0.907 (0.098, 8.431) | 0.932 | 1.009 (0.112, 9.109) | 0.994 |
3-4 | 0.366 (0.019, 7.221) | 0.509 | 0.280 (0.015, 5.128) | 0.391 |
ypTNM | 2.432 (0.305, 19.371) | 0.401 | 3.079 (0.424, 22.371) | 0.266 |
Histological type | 0.913 (0.603, 1.380) | 0.665 | 0.808 (0.539, 1.213) | 0.304 |
Lauren classification | 1.517 (0.964, 2.389) | 0.072 | 1.431 (0.919, 2.227) | 0.113 |
Grade of differentiation | 1.360 (0.673, 2.749) | 0.392 | 1.228 (0.630, 2.393) | 0.546 |
Vascular or lymphatic invasion | 1.903 (1.265, 2.862) | 0.002 | 1.635 (1.101, 2.427) | 0.015 |
Nervous invasion | 1.003 (0.662, 1.520) | 0.988 | 0.993 (0.662, 1.490) | 0.973 |
Mandard TRG | 2.034 (1.052, 3.934) | 0.035 | 2.220 (1.162, 4.241) | 0.016 |
Adjuvant treatment | 2.464 (1.393, 4.358) | 0.002 | 2.339 (1.337, 4.092) | 0.003 |
As neoadjuvant therapy has been recommended to apply in gastrointestinal malignancy by various treatment guidelines in the world, the assessment of the effectiveness of preoperative therapy is increasingly important. Although the posttreatment TNM stage (ypTNM) has been widely accepted, this system is not always associated with prognosis in multivariable analysis, such as ypT stage [
These systems could be classified into two mainly categories on the basis of comparison methods: compare the relative amount between fibrosis and residual tumor, such as the Mandard [
However, some disadvantages do exist in these systems. Firstly, there are numerous methods without universal agreement. According to a recently published survey from six continents, the standards applied were various in different countries [
Secondly, although this system is often an indicator to the prognosis in the univariable analysis, sometimes TRG lost its statistical significance in multivariable analysis [
Thirdly, different researches using the same grading system supported different boundaries to keep the maximum predicting ability. This conflict is more obvious in the Mandard TRG, partly because of its higher number of tiers [
In our study, we confirmed the Mandard TRG was associated with OS and DFS in univariable analysis, especially merged into TRG 1-2 vs. 3-5. This boundary was in line with some studies [
In multivariable analysis, we found TRG lost its prognostic significance, while the metastasis of lymph node owned the greatest hazard ratio. Therefore, the stratification analysis was performed to detect the role of TRG in patients with different lymph node status. The result showed the tumor regression grading system retrieved its prognostic significance in ypN+ patients while not in the ypN- group. On this point, a Japanese team found TRG was related to OS when a subset analysis of lymph node stage was conducted; however, they suggested this in patients with less than 7 positive nodes [
In addition to stratification, the combination of TRG and lymph node stage was also used to predict the survival [
Except for the status of lymph node, other pathological factors including T stage [
There are some limitations in the present study. The study is retrospective and conducted at a single institution, which means a potential selection bias might exist. The sample size is small, which leads to a limited number of patients and excessive hazard ratios in the stratified analysis. The follow-up time is not long enough, which might hide the significance of TRG in lymph negative patients. But our study forced on a specific group of patients and confirmed the value of TRG in patients with lymph node metastasis. This suggested the system could contribute to the assessment of therapeutic effect and hinted that the significance of this system might be different according to clinicopathological characteristic of patients, which could partly account for the reason that TRG was not an independent predictive factor.
TRG was not an independent factor for survival, but the system regained its prognostic significance in the patients with lymph node metastasis. Therefore, the combined application of TNM and TRG system could make a contribution to the evaluation of the efficacy of neoadjuvant therapy.
Neoadjuvant chemotherapy
Gastric cancer
Tumor regression grade
Vascular or lymphatic invasion
Nervous invasion
Overall survival
Disease-free survival
Tumor-node-metastasis
Postneoadjuvant therapy.
The datasets analyzed during the current study are not publicly available due to the presence of identifiable patient information but are available from the corresponding author on reasonable request.
The study was reviewed and approved by the Faculty of Science Ethics Committee at Liaoning Cancer Hospital and Institute (Cancer Hospital of China Medical University).
The authors declare that there is no conflict of interest regarding the publication of this article.
YT performed the majority of experiments, analyzed the data, and drafted the manuscript; YM Z contributed to the reevaluation of pathological characteristics; YZ reviewed and revised the manuscript; ZS assisted in the collection and analysis of data; DL contributed greatly to the reevaluation of pathological characteristics and provided professional instructions; JZ supervised the study and provided critical revision of the manuscript.
Table S1: multivariable analysis for patients with no lymph node metastasis.