Does the ypTNM-stage adequately predict long-term survival rates in gastric cancer patients receiving neoadjuvant chemotherapy followed by radical resection?

Abstract

Background

Following neoadjuvant chemotherapy (NAC) for resectable gastric cancer, the prognostic adequacy of the UICC staging system needs to be investigated. In particular to explore whether the ypTNM curves for radically resected gastric cancer patients receiving NAC follow the stage-matched survival curves of radically resected chemo-naïve patients (pTNM). Further, to disclose any interaction between the TNM-response mode to NAC and stage-specific survival rates, i.e., whether survival for a particular pathological disease stage was dependent on whether this was reached through a downstaging or as stable disease following NAC.

Material and methods

Retrospective study on radically resected patients ≤ 75 years of age with gastric adenocarcinoma stages I-III diagnosed during 2001–2016. The patients constitute two population-based cohorts; the SURG-group with n = 121 patients treated before 2007 when NAC was introduced, and the NAC-group with n = 126 patients diagnosed since early 2007, receiving NAC and subsequent radical resection.

Results

Long-term survival rates were similar when specific ypTNM-stages were compared to their corresponding pTNM chemo-naïve counterparts. The dichotomised N0 vs. N + had a substantial impact on the long-term survival rates in both groups, however, no discrepancy in long-term survival rates between pN0 vs. ypN0, and pN + vs. ypN + was found. The pathological stage determined long-term survival rates irrespective of the baseline disease stage, as no interaction between the response mode and stage-specific survival rates was found.

Conclusions

Survival curves for specific ypTNM-stages following NAC did not differ from the corresponding survival curves of their chemo-naïve pTNM counterparts. The interpretation is that NAC affected the gastric cancer, lymph nodes, and micrometastases, in such a way that the final ypTNM-stage provided similar prognostic information as the chemo-naïve pTNM-stages. Survival rates were contingent on the final ypTNM-stages alone, and not influenced by the response mode to reach that particular disease stage, or predetermined by the original clinical TNM-stage.

Keywords:

• Gastric cancer
• neoadjuvant treatment
• TNM staging
• survival

Author’s contributions

All the authors conceived the idea, designed the work and obtained the data. A.D Sandø and E.A Bringeland analysed and interpreted the data. A.D. Sandø and E.A Bringeland wrote the manuscript and prepared the figures and tables. E.A. Bringeland and J.E Grønbech critically revised the manuscript. All authors are accountable for the contents of this work. All authors read and approved the final manuscript.

Ethical approval

Research in this study has been performed in accordance with the Declaration of Helsinki and has been approved by the Norwegian Regional Ethics Committee (case number 2016/2173). We confirm that all methods were carried out in accordance with the relevant guidelines and regulations. ‘The need for informed consent was waived by the ethics committee, Regional Ethics Committee Midt-Norge, because of the retrospective nature of the study.’

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated and analysed during the present study are not publicly available due to hospital policy, but are available from the corresponding author on reasonable request.

Disclaimer

The study has used data from the Cancer Registry of Norway. The interpretation and reporting of these data are the sole responsibility of the authors, and no endorsement by the Cancer Registry of Norway is intended nor should be inferred.

Additional information

Funding

This research was supported by the Norwegian Cancer Fund, FFU (Joint Research Committee St.Olavs Hospital, Norway) funding information 2020/39769, and the Department of Surgery, St. Olavs Hospital, Trondheim University Hospital. The funders had no role in the study design, data collection and analysis, or preparation of the manuscript.