Comparison of tumor markers
The changes of tumor markers CEA and CA199 in the serum of the two groups after treatment were observed. In the period of chemotherapy, there were 7 patients in the experimental group who showed persistent abnormality of CEA, accounting for 31.8%, 9 patients in the control group, accounting for 39.1%, and no statistically significant difference between the two groups (χ2=0.262, P=0.609). During chemotherapy, there were 3 patients in the experimental group showed persistent abnormality of CA199, accounting for 13.6%, 10 patients in the control group, accounting for 43.4%, and the differences between the two groups were statistically significant (χ2=4.874, P=0.027).
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Comparison of adverse reactions
There were different degrees of reaction of blood system, digestive system and peripheral nervous system in the two groups after treatment. There was a statistical difference between the experimental group and the control group in hemocytopenia, thrombocytopenia, nausea and vomiting, and peripheral nerves reaction, which was statistically significant (P<0.05). However, there was no significant difference in hemoglobin reduction and diarrhea (P>0.05) (Table 2).
(To view a larger version of Table 2, click here.)
Quality of life (QOL) ratings
The QLQ-C30 score was 42.32±16.20 in the experimental group, 79.53±18.54 in the control group, the t value was 7.156, P<0.0001. The QOL in the experimental group was significantly lower than that in the control group, and the difference was statistically significant (P<0.05).
DISCUSSION
Gastric cancer is one of the most common malignancies. It is reported by the world health organization’s “world cancer report 2014” that the number of new cases of gastric cancer and the number of deaths in China are the highest in the world. Shanghai is the region with high incidence of gastric cancer, and the incidence is increasing year by year. Patients with clinical diagnosis are mostly in advanced progress and the prognosis is poorer (1). At present, the radical operation and postoperative chemotherapy for gastric cancer is standard treatment, the study has shown that compared with separate surgery, 3-year survival rate, progression-free survival and recurrence rate were improved by postoperative adjuvant chemotherapy (2). CLASSIC study results provide important evidence for the value of postoperative adjuvant chemotherapy for gastric cancer. A total of 1.035 II–III stage gastric cancer patients after surgery were randomly assigned into the group of capecitabine combinated with oxaliplatin (XELOX project) group (n=520) or observation group (n=515), the results showed that postoperative adjuvant chemotherapy increased the survival rate from 59% to 74% (HR =0.56; 95% CI: 0.44–0.72; P<0.0001) (3). Postoperative chemotherapy is an important treatment of gastric cancer, the purpose is to control the local recurrence and eliminate tiny metastases, thus improve postoperative disease-free survival and overall survival, but the overall therapeutic effect of gastric cancer is still unsatisfactory. The unsatisfactory effect of chemotherapy in advanced gastric cancer is an important factor for postoperative recurrence, multidrug resistance of chemotherapy drugs is responsible for unideal chemotherapy effect (4). How to improve the sensitivity of cancer cells to chemotherapy drugs and reduce the damage of chemotherapy drugs to normal tissue cells has become an important research topic.
Hypoxia is one of the basic characteristics of the microenvironment of solid tumor, that the tumor tolerates hypoxia is important mechanism of enhancement ability in the tumor development and tumor transfer, it also can induce multi-drug resistance, which leads to poor chemotherapy effect (5). Hypoxia can induce gene expression related to blood vessel formation and hypoxia metabolism, and hypoxia-inducible factor-1 (HIF-1) plays a very important role (6,7). The application of hyperbaric oxygen as a sensitizer and disinfectant for malignant tumor chemotherapy has been recognized. Hyperbaric oxygen can improve oxygen levels of hypoxic cells within tumors, it enhanced the sensitivity of tumor cells to chemotherapy drugs by down-regulating the expression of HIF-1, the drug concentration in the tumor was increased. In this way, the effect of hyperbaric oxygen on the sensitization of chemotherapy was achieved (8). In this study, 1-year image evaluation for recurrence or lymph node metastasis in experimental group and control group are 1 case (4.54%) and 6 cases (26.0%) respectively, the recurrence rate in the experimental group was significantly lower than that in the control group, and the difference between the two groups was statistically significant (χ2=3.972, P=0.046). Hyperbaric oxygen combined with chemotherapy can reduce tumor recurrence in the near future and prolonged the patient’s survival period, which could be applied to clinical practice.
