Research Article: The role of surgery and radiation in advanced gastric cancer: A population-based study of Surveillance, Epidemiology, and End Results database

Date Published: March 12, 2019

Publisher: Public Library of Science

Author(s): Shuang Ye, Lu Wang, Zhigang Zuo, Yanping Bei, Kaitai Liu, Jason S. Gold.

http://doi.org/10.1371/journal.pone.0213596

Abstract

Chemotherapy is the standard approach for advanced gastric cancer, while the role of local therapy such as surgery and radiation for this population remains controversial. Our purpose is to evaluate the effect of local therapies on cancer specific survival (CSS) for advanced gastric cancer patients.

Four subgroups of patients in different treatment strategies: surgery, radiation (RT), surgery and radiation (Surgery+RT), no surgery/no radiation (No Surgery/No RT) were identified from the Surveillance, Epidemiology, and End Results (SEER)-registered database. The risk factors and the survival outcomes were analyzed by multivariable Cox regression models and Kaplan-Meier methods.

A total of 10,354 patients were eligible with 6658 males and 3696 females. The 5-year CSS in the four subgroups of “Surgery”, “RT”, “Surgery+RT” and “No Surgery/No RT” were respectively 8.9%. 5.7%, 19.8% and 3.2%, which were significantly different in multivariate Cox regression (P<0.001) and univariate log-rank test (P<0.001). Advanced stage categories were defined as stage I, II and III of T/N category according to different initial T and N status following American Joint Committee on Cancer (AJCC) staging principle. Further analysis showed that patients in the group of “Surgery+RT” have significant benefits of survival specifically on stage II and III of T/N category. “Surgery+RT” group and “Surgery” group patients have similar survival time in stage I of T/N category. Moreover, we also found CSS benefits from the administration of “Surgery+RT” in the patients aged both ≥75 and <75 years. Remarkably, patients in “Surgery” group have no different survival time with “RT” group in age category of 75 years and older. Local therapies, including surgery, radiation, and combination of both might associate to improve survival in advanced gastric cancer patients, but confounding due to disease extent and physical status cannot be excluded.

Partial Text

In the past few decades, there has been a great decrease on the gastric cancer incidence all over the world [1]. Nevertheless, the problem of poor prognosis still exists in gastric cancers which is the 3rd cause to cancerous deaths in the world [2]. The diagnosis of gastric cancer is general in IV stage with metastatic disease, and the prognosis is usually poor [3–4]. Studies showed that with no treatment, the median survival of advanced gastric cancer patients was just three to five months, and which could be extended to approximately ten months with palliative chemotherapy [5–6]. Postoperative concurrent chemoradiation has been used to be the standard treatment for locally advanced gastric cancer patients [7–8]. There are several types of treatment strategies for advanced gastric cancer, such as radiotherapy, chemotherapy and palliative gastrectomy [9]. Chemotherapy can relief symptoms as well as enhance life quality and survival for advanced gastric cancer patients [10–11]. Until now, there were conflicting evidences on effects in patients with advanced gastric cancer. External-beam RT as a single modality shows minimal value to advanced gastric cancer patients and does not improve survival [12]. A population-based Surveillance, Epidemiology, and End Results (SEER) analysis showed that only modest improvements in prognosis for metastatic gastric cancer were observed in patients who underwent and in patients who did not undergo palliative gastrectomy [13]. However, patients with stage IV gastric cancer are a heterogeneous group and the role of local therapies for this population remain controversial.

There are high incidents of gastric cancer in lots of nations and regions worldwide. By estimate of the National Cancer Institute’s Surveillance, the number of diagnosed gastric cancer cases in the year of 2016 was about 26,370, and about 10,730 of the patients were estimated to have died of gastric cancer [17]. Historical analysis indicated that there were 34% of the patients whose cancer cells had already spread to other sites when they were first diagnosed with cancer [18], which implies that approximately 30% patients were diagnosed with advanced gastric cancer. Thus, it is important to build standard treatment strategies for them. Similarly, according to our findings, stage IV patients accounted for around 30% of the total number of gastric cancer population, and this ratio remained stable from 2004 to 2013. As we known, because of the heterogeneous extent of primary sites, different degree of disease progression, and patient performance status, it is highly hard to perform prospective randomized controlled trials for patients with advanced gastric cancer. Hence, it is crucial to conduct retrospective analysis for clinical studies on advanced gastric cancer. Our study showed that surgery and radiation might associate with survival improvement in advanced gastric cancer patients according to specifical extent of primary disease and performance status. As far as we know, this study is the biggest population-based retrospective study for the evaluation of the recommended treatment strategies in advanced gastric cancer.

Surgery and radiation might associate with survival improvement in patients with advanced gastric cancer, but confounding due to disease extent and physical status cannot be excluded. However, further prospective studies are required for verification since the study we conducted is a retrospective analysis.

 

Source:

http://doi.org/10.1371/journal.pone.0213596

 

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