JMIR Publications

ABSTRACT

Background:

Gastric cancer, also known as gastric cancer, develops from the lining layers of the Gastric. The cancer may spread from the gastric to other parts of the body, particularly the liver, lungs, bones, lining of the abdomen and lymph nodes. The cancer survival rate measures the proportion of people with cancer who will be alive at a certain time after diagnosis, given that they did not die from something other than their cancer. Survival rates are important for prognosis, social planning, new intervention evaluation and future expectation. Gastric cancer currently ranks fourth in cancer incidence worldwide and is the most common type of cancer among Japanese men [1]. More than 70% of cases occur in developing countries [1]. The gastric cancer incidence rate differs in the Middle East from very high in Iran (26.1/100000) to low in Israel (12.5/100000) and very low in Egypt (3.4/100000) [2-4]. Epidemiological studies showed that the prevalence of H. pylori is almost similar in those countries with a high level of infection in childhood. H. pylori infection prevalence, distribution pattern of virulence factors, diet and smoking could not have explained the difference in cancer rate. This reflects the multifactorial etiology of gastric cancer and suggests that H. pylori infection does not always directly correlate with the risk for gastrointestinal disease, such as gastric cancer. In Jordan, gastric cancer accounts for 2.7% of all newly diagnosed cancer cases. It affects males more than females with ratio of 1.7:1. Gastric cancer contribute to 4.6% of all deaths due to all types of cancer being in the sixth position among top ten cancer mortality in Jordan [4]. Last years witnessed increase in cases of gastric cancer and became in the ninth position of top ten causes of cancer for male in Jordan and sixth cause of death among cancer causes of death. Very few studies had investigated survival of gastric cancer and its determinants (5).

Objective:

This study aimed to determine survival rate and its determinants among Jordanian patients who were diagnosed with gastric cancer in the period between 2010 and 2014.

Methods:

This study was based on Jordan cancer registry which accounts more than 95% of all cancer cases in Jordan. Jordanian cancer registry uses forms for data collection to collect data about socio-demographic characteristics including national identification number, name, age, marital status, and address and information related to cancer including histopathology, morphology, stage of cancer, location of tumor, date of diagnosis, date of last visit, and outcome. All gastric cancer cases among Jordanians who were registered in Jordan cancer registry during the period of 2010-2014, with or without histopathology report, were included in the study and analyzed using the survival analysis. Patients with multiple cancers were not included in this study. The demographic and clinical characteristics of each registered patient were obtained from the Jordan cancer registry files and hospital medical records through the standard data request form. Data about the type and stage of cancer were obtained from histopathology reports from governmental and private laboratories in addition to the medical records of hospitals. The histopathology type was categorized according to cancer site. The cancer stage was classified into localized, regional, and distant metastasis and unknown stage. To identify the vital status of these patients, date of the last visit was obtained from the medical records. Besides, the vital status was ascertained from the Civil Registration Department using a unique national identification number. Only cancer related deaths were recorded as “death” in the survival analysis. The few non-cancer-related deaths, as ascertained from the Civil Registration Department, were considered as censored cases. A period of observation was sets for the included patients from the date of diagnosis to the last date of observation if the patient was alive (31th Dec 2016) and to the date of death if the patient died during the observation period. The follow-up end point was death from cancer. Ethical approval was obtained from the Institutional Review Board at Ministry of Health. Data were analyzed using Statistical Package for Social Sciences Software (SPSS) version (23 IBM). Data were described using means and percentages. The overall survival was estimated using Kaplan-Meier product limit technique. Log-rank test was used to compare survival rates between groups. Cox-regression analysis was used to determine factors associated with the time to death. A ???? value < 0.05 was considered statistically significant.

Results:

A total of 1388 new cases of gastric cases were recorded during the period 2010-2014. Of those, 872 (62.8%) were Jordanians, 60.5% were males and 39.5% were females. The mean age at diagnosis was 58.9 year (59.7 year for males and 57.8 year for females). Almost half of patients (48.4%) aged above 60 years. The most commonly affected age group was 60-69 years. The majority of patients were married. About 20.4% were current or past smokers. The grade of tumor was poorly differentiated in 39.6% of the cases while 37.9% of cases had unknown stage. About 40.3% of all cases underwent surgical interventions and 31% had received chemotherapy. The follow up ranged from 0 to 7.1 year with a mean of 1.5 year. The median follow-up time was 1.6 year. The proportion of patients surviving each time interval and the cumulative survival are shown in Figure 1. The overall 5-years survival rate was 37.7% and the median survival was 1.48 year (95% CI: 1.179-1.783). The 5-year survival rate was 93.5% among non-Jordanian patients and 37.7% among Jordanian (???? < 0.005). The 5-year survival rate was 89% in patients with well differentiated grade cancer and 32% in patients with poorly differentiated grade cancer (???? < 0.005). The 5-year survival rate decreased significantly from 43% for the age <40 years to 29.8% for the age ≥70years (???? < 0.005). The survival rate decreased significantly with the advanced stage of the disease. The 5-year survival rate was 75% for localized stage, 48% for regional stage, and 22.7% for distant metastasis; ???? < 0.005). The median survival for patients with gastric cancer according to demographic and clinical characteristics is shown in Table 1. The 5-years survival rate of patients whom underwent surgical procedures without neither chemical nor radiological therapy was 43.3%. Patients who were treated with chemotherapy only had a 5-years survival rate of 27.8% while Patients who received radiotherapy only had 5-years survival rate of 15.7%. The 5-years survival rate was 43.1% for patients who didn’t undergo any therapy. Table 2 shows the multivariate analysis of factors associated with the hazard of death in Cox-regression analysis. The only factors that were significantly associated with death were age, nationality, and grade and stage of cancer. The hazard of death increased significantly with increased age being the highest in age ≥70 years (HR=1.68). The hazard of death increased significantly among Jordanian patients compared to non-Jordanian patients (HR=5.27). The hazard of death was significantly higher for those with poorly differentiated cancer compared to those with well differentiated cancer (HR=5.93). The hazard was much higher for patients whose cancer stage was regional (HR = 2.35) and those with distant metastasis (HR = 5.65) compared to those with localized cancer.

Conclusions:

Data on the survival analysis of Gastric cancer are scant in the Eastern Mediterranean countries including Jordan. Previous studies in other countries have reported variable Gastric cancer survival rates. About 71% of Gastric cancer cases occurred in less developed countries [6]. The highest incidence of gastric cancer was in Asia, Latin America and the Caribbean and the lowest incidence in Africa and northern America [6]. The Republic of Korea had the highest rate of Gastric cancer followed by Mongolia and Japan [6]. This study showed that the overall 5-years survival rate was 37.7% of all patients with estimate median 1.481 years (95%C.I. 1.179-1.783). This rate is higher than the reported rates from different countries in the Eastern Mediterranean region like Egypt which had median overall survival rate 6 months (95% CI 3.3-8.9) [7]. Various research studies from Iran have reported 5-year survival rates of gastric cancer of 12.8% [5]. The disparities in Gastric cancer survival between Eastern Mediterranean countries may be attributed to several factors including differences in socio-economic status, stage at diagnosis, treatment, physician characteristics, and hospital factors. The better survival in Jordan compared with other countries in the region might be explained by the fact that cancer care in Jordan is more advanced in comparison to most neighboring countries, and the country hosts many local and western-trained physicians who can deliver various cancer treatment modalities [8]. Currently, the King Hussein Cancer Foundation and Center (KHCC) treats around 60% of cancer cases in Jordan. KHCC is a specialized tertiary hospital that provides all treatment modalities and services to Jordanian patients as well as other patients from neighboring countries. However, further studies are needed to examine the differences in Gastric cancer survival between these countries. There is no significant difference in the survival between males and females in the univariate analysis and multivariate analysis. The lack of gender differences in survival rates was reported in some of the previous studies. This study showed that the hazard of death increased significantly with increased age being the highest in age ≥70years. This result was reported in other studies [5,7] that showed that older patients had a poorer survival rate compared to younger patients. The contradictory results of previous studies on age may be due to inclusion of patients from single referral centers and poor adjustment for the effect of possible confounders. Different clinical and pathological prognostic factors have been proposed for gastric cancer in the literature, including location of the tumor, tumor stage, differentiation of tumor, and surgical and distant metastasis. The multivariate analysis using Cox-regression analysis showed that age, nationality, grade and stage were significant predictors of survival. The hazard of death was significantly higher for those age categories >70 years patients compared to those other age categories due to increase probability of death with age. The hazard of death was significantly higher for Jordanian patients compared to non-Jordanian that is explained by short period of follow up for non-Jordanian patients because they departed after they received medical treatment so couldn’t followed up. The hazard of death was significantly higher for those with poorly differentiated cancer compared to those with well differentiated cancer. Moreover, it was much higher for patients whose cancers stage was regional and those with distant metastasis compared to those with localized cancer. The study concluded that the earlier the stage at diagnosis, the higher the chance of survival. The differences in the survival according to the stage are explained by the differences in the extent to which the cancer has spread and how many lymph nodes have been affected. Data from Jordan cancer registry should be interpreted with caution. As many registries in the region, Jordan cancer registry does not collect information on other possible predictors of mortality such as occupation, level of education, economic status, and comorbidity. Therefore, our estimates of hazards ratio might be biased because of not adjusting for the effect of unmeasured variables. In conclusion, this study showed that the overall 5-years survival rate among patients with gastric cancer was 37.7%, which is higher than the reported rates from different countries in the Eastern Mediterranean region like Egypt. Increased age, poor differentiation and advanced cancer stage were associated with lower survival rates. Survival rate of patients who underwent surgical interventions alone was 43.3%, while the survival rates among those who received chemical therapy or radiotherapy alone were 27.8% and 15.7%, respectively which disparities with other regional study, which can be interpreted by that; patients underwent surgical interventions in early stages of cancer while chemotherapy and radiotherapy given to much worse cases. It is well established that gastric cancer is one of those cancers that can largely be prevented by the early detection and removal of adenomatous tissues, and survival is therefore significantly better when Gastric cancer is diagnosed while being still localized. Screening strategies are needed for early detection of Gastric cancer.