[Survival analysis of malignant tumors in cancer registration areas of Hubei province in China, 2013 to 2015]

Objective: To analyze the survival of newly diagnosed malignant tumors in cancer registration areas of Hubei Province from 2013 to 2015. Methods: From January 1, 2013 to December 31, 2015, all newly diagnosed malignant tumors were collected from cancer registration areas in Hubei Province, and patients were followed up using a combination of active and passive methods. Cancer survival was analyzed using the strs package in Stata software. Observed and expected survival were calculated using the life table and Ederer Ⅱ methods, and the difference in survival rate of patients with different sex, age, urban and rural areas and different cancer species was compared. Results: From 2013 to 2015, 83 987 new malignant tumors were diagnosed in cancer registration areas in Hubei Province, including 45 742 males (54.46%) and 38245 females (45.54%). The overall 5-year relative survival rate was 41.46%, 34.43% for men and 49.63% for women. With the increase of age, the observed survival rate and relative survival rate of patients of different genders showed a decreasing trend. The 5-year relative survival rate of patients with malignant tumors was 47.58% in urban areas and 26.58% in rural areas. The observed survival rate and relative survival rate in rural areas were significantly lower than those in urban areas. The overall 5-year relative survival rates for common malignancies were 20.61% for lung cancer, 15.36% for liver cancer, 22.89% for esophageal cancer, 34.92% for gastric cancer, and 54.87% for colorectal cancer. In addition, the 5-year relative survival rates of common malignant tumors in women were 78.65% for breast cancer and 52.55% for cervical cancer. Conclusions: In Hubei Province, the survival rate of malignant tumors is different among different genders, regions, age groups and cancer species. Prevention and treatment and health education should be strengthened for malignant tumor patients in rural areas and those with high incidence and low survival rate such as liver cancer and lung cancer, and relevant strategies should be formulated according to the gender and age distribution characteristics of different cancer species.

[Progress on development and application of the diet-related inflammatory index in cancer epidemiological studies]

Cancer is a major public health problem worldwide, causing an more serious burden of disease. Inflammation is considered a predisposing factor for cancer with close relationship with its incidence. In recent years, the public and epidemiologists has paid more attention to the association between nutrition and cancer and other chronic diseases in the perspective of inflammation. This paper summarizes the development and application of the diet-related inflammatory index in cancer epidemiological studies based on the literature retrieval of common diet-related inflammatory index. Firstly, we highlight the common diet-related inflammatory indices and their construction methods, such as the Dietary Inflammatory Index, a literature-derived diet-related inflammatory index, and the Empirical Dietary Inflammatory Index, an empirically derived diet-related inflammatory index, and so on. Secondly, the epidemiological research progress on the commonly used diet-related inflammatory indices is briefly introduced. Finally, the advantages and disadvantages of the two types of this inflammatory indices are also briefly described for the purpose of providing reference for nutrition epidemiological studies of cancer and other chronic diseases in China.

[Choice and application of time scale selection for Cox proportional hazards regression model in cohort studies]

Cox proportional hazards regression model (Cox model) is the most commonly used multivariate approach in time-to-event data analysis. A vital issue in fitting Cox model is choosing the appropriate time scale related to the occurrence of the outcome events. However, few domestic studies have focused on selecting and applying time scales for Cox model in the analysis of cohort study data. This study briefly introduced and compared several time scales in the reports from literature; and used data from the Shanghai Women's Health Study to illustrate the impact of different time scales on data analysis results, using the association between central obesity and the risk of liver cancer as an example. On this basis, several suggestions on selecting time scales in Cox model are proposed to provide a reference for the analysis of cohort study data.

[Statistical methods for relative risk estimation and applications in case-cohort study]

Objective: To systematically introduce the design of case-cohort study and the statistical methods of relative risk estimation and their application in the design. Methods: First, we introduced the basic principles of case-cohort study design. Secondly, Prentice's method, Self-Prentice method and Barlow method were described in the weighted Cox proportional hazard regression models in detail, finally, the data from the Shanghai Women's Health Study were used as an example to analyze the association between obesity and liver cancer incidence in the full cohort and case-cohort sample, and the results of parameters from each method were compared. Results: Significant association was observed between obesity and risk for liver cancer incidence in women in both the full cohort and the case-cohort sample. In the Cox proportional hazard regression model, the partial regression coefficients of the full cohort and the case-cohort sample fluctuated with the adjustment of confounding factors, but the hazard ratio estimates of them were close. There was a difference in the standard error of the partial regression coefficient between the full cohort and the case-cohort sample. The standard error of the partial regression coefficient of the case-cohort sample was larger than that of the full cohort, resulting in a wider 95% confidence interval of the relative risk. In the weighted Cox proportional hazard regression model, the standard error of the partial regression coefficient of Prentice's method was closer to the parameter estimates from full cohort than Self-Prentice method and Barlow method, and the 95% confidence interval of hazard ratio was closer to that of the full cohort. Conclusions: Case-cohort design could yield parameter results closer to the full cohort by collecting and analyzing data from sub-cohort members and patients with the disease, and reduce sample size and improve research efficiency. The results suggested that Prentice's method would be preferred in case-cohort design.

[Report of incidence and mortality of gallbladder cancer in China, 2014]

Objective: The incidence and mortality of gallbladder cancer from Chinese cancer registries in 2014 were analyzed to describe the prevalence of gallbladder cancer in China. Methods: Incidence and mortality data of gallbladder cancer in 2014 derived from registration data in 2017, collected by the National Central Cancer Registry (NCCR). Qualified data from 339 cancer registries were calculated after evaluating. According to the national population data of 2014, the gallbladder cancer incidence and mortality of China in 2014 were stratified by the area, gender and age.The age composition of standard population of Chinese census in 2000 and Segi's population were used for age-standardizes incidence and mortality in China and worldwide. Results: 339 cancer registries cover a total of 288 243 347 population including 146 203 891 males and 142 039 456 females (144 061 915 in urban and 144 181 432 in rural areas). The mortality to incidence ratio of gallbladder cancer was 0.74. The morphologically verified cases (MV%) and death certificate-only cases (DCO%) were 48.38% and 2.66%, respectively. Unclear diagnosis cases (UB%) was 0.48%. The crude incidence of gallbladder cancer in China in 2014 was 3.82/100 000, which accounted for 1.37% of new cancer cases (4.48/100 000 in urban areas and 3.01/100 000 in rural areas, 3.59/100 000 for male and 4.05/100 000 for female). Age-standardized incidence rates by Chinese standard population (ASR China) and world standard population (ASR world) were 2.38/100 000 and 2.37/100 000, respectively, and the cumulative incidence rate (0-74 age years old) was 0.27%.Besides, the crude mortality of gallbladder cancer was 2.86/100 000 (3.47/100 000 in urban areas and 2.12/100 000 in rural areas, 2.59/100 000 for male and 3.14/100 000 for female). Age-standardized mortality rates by ASR China and ASR world were 1.72/100 000 and 1.71/100 000, with a cumulative mortality rate (0-74 age years old) of 0.19%. Conclusion: The incidence and mortality of gallbladder cancer were significantly different between the city and country, while not obviously different between the female and male.