| The Jinchang Cohort is population based on workers at a comprehensive enterprise that includes mining,ore dressing,smelting,the chemical industry,and so on.In the production process,a variety of heavy metals and their compounds are generated.Because industrial and living areas overlap,the cohort is doubly threatened by both their professional environment and atmospheric pollution,drawing the concern of the enterprise and all sectors of society.For this purpose,we used retrospective cohort and cross-sectional study designs to comprehensively analyze cancer burden from three dimensions,including epidemiology,economic burden,and degree of harm,in order to understand trends in cancer mortality and harm in the Jinchang Cohort and to identify key cancers affecting the cohort and their growth rate.On the basis of the trend analysis of cancer burden,we fit thirteen years of cancer mortality data from the Jinchang Cohort using six kinds of forecasting methods to compare relative fit and to select good forecasting methods for the prediction of cancer mortality trends.Ultimately,we aim to reduce the cancer burden in the cohort and to provide scientific evidence for developing cancer prevention strategies and performing effectiveness evaluation in the Jinchang Cohort.The main research conclusions were summarized as follows:(1)Trends in cancer mortality were analyzed using 3375 cases of death data from the Jinchang Cohort during 2001-2013.The results indicated that the crude mortality rates of cancer continuously increased from 161.86 per 100,000 in 2001 to 291.43 per 100,000 in 2013,with an average annual increase of 5.02%(7.95%in females compared to 4.80%in males).The seven leading cancers were lung,gastric,liver,esophageal,colorectal,brain,and breast cancers.Over the study period,the crude mortality rates(CMR)increased but the age-standardized mortality rates(ASMR)decreased for lung cancer;the CMR and ASMR for gastric,liver,esophageal,and colorectal cancers showed increasing trends.The average annual growth rates in CMR for lung cancer,gastric cancer,and colorectal cancer were 4.77%,5.62%,and 12.89%,respectively,in total over the study period.Miners(including ore dressing workers)in the jinchang cohort had the highest CMR at 375.38/100,000,followed by non-mining workers at 178.89/100,000,and cadres at 155.72/100,000.CMR was significantly different between the three types of professionals(P<0.001).The average annual growth rates in cancer among cadres,non-mining workers,and miners were 12.53%,2.15%,and 8.63%,respectively.Lung cancer mortality was significantly different between the three types of professionals;lung cancer mortality among miners,non-mining workers,and cadres were 137.86/100,000,60.20/100,000,and 53.85/100,000.Miners had the highest mortality in the Jinchang Cohort.Occupational exposures experienced by miners were associated with the highest cancer mortality rates,at 375.38/100,000,of three occupational exposure settings assessed,followed by refining and smelting exposure with 154.81/100,000,and unexposed controls with 142.12/100,000.Cancer mortality was significantly different among the three kinds of environmental exposures(P<0.001).The average annual growth rates of cancer CMR among miners,refiners and smelters,and controls were 8.63%,9.98%,and 3.29%,respectively.Lung cancer mortality was not significantly different among the three kinds of environmental exposures(P = 0.153),with increasing trend in each.(2)Trends in the direct economic burden faced by cancer inpatients in the Jinchang Cohort were analyzed using 5223 medical records from cancer inpatients during 2001-2010.The results showed that the leading seven cancers in terms of per capita hospitalization costs were bladder,gastric,colorectal,esophageal,breast,and liver cancer.The leading seven cancers in terms or average daily cost of hospitalization were breast,gastric,colorectal,esophageal,bladder,lung,and liver cancer.(3)Case fatality rates among cancer inpatients and degree of harm to the Jinchang Cohort due to cancer were analyzed respectively using medical records from cancer inpatients during 2001-2010 as well as death data.The results show that the highest case fatality rates identified in the study were liver cancer at 34.62%in 2001-2005,and 30.32%in 2006-2010,with a decrease of 12.40%between the two periods;followed by lung cancer,at 17.44%in 2001-2005,and 14.78%in 2006-2010,with a decrease of 15.27%between the two periods.Lung cancer,liver cancer,and gastric cancer were the top three ranked cancers in PYLL;liver cancer,lung cancer,and gastric cancer were the top three ranked cancers in WPYLL.Lung cancer,liver cancer,and gastric cancer were thus the most important cancers that affected both lifespan and employment in the jinchang cohort from 2001-2013.The top three cancers in terms of APYLL and AWPYLL were breast cancer,brain cancer,and liver cancer.Non-mining workers had the highest PYLL and WPYLL,followed by miners,and finally by cadres.The top four cancers in terms of APYLL and AWPYLL among non-mining workers were breast cancer,brain cancer,liver cancer,and colorectal cancer;and brain cancer,breast cancer,liver cancer,and colorectal cancer in miners.(4)On the basis of the trend analysis of cancer burden in the Jinchang Cohort,cancer,male cancers and lung cancer were fitted using six kinds of prediction methods:dynamic series,linear regression,exponential smoothing,ARIMA model,grey model(GM),and Joinpoint regression.Weight coefficients of combination models were calculated by four methods:the arithmetic average method,the variance inverse method,the mean square error inverse method,and the simple weighted average method.Prediction methods were compared using the indicators of mean square error(MSE),mean absolute error(MAE),mean absolute percentage error(MAPE),fitting precision.Age-specific death rates of cancer,lung cancer,esophageal cancer,and liver cancer were fitted using the Joinpoint regression.The results showed that the cancer mortality was fitted and compared using six kinds of forecasting methods;the fitting precision of the Joinpoint linear regression had the highest accuracy at 87.64%,followed by linear regression,the dynamic series,GM(1,1),exponential smoothing,and ARIMA(1,0,0)at 87.26%,86.99%,86.25%,85.72%,and 81.98%,respectively.Prediction accuracy of the combination model derived from GM(1,1)and linear regression,with accuracy of 99%or more,was higher than that of the combination model derived from ARIMA(1,0,0)and GM(1,1).The combination model derived from the GM(1,1)and linear regression,with weight coefficients based on the arithmetic average method and the mean square error inverse method,had the best prediction effect of the four weight calculation methods.The cancer mortality of males was fitted and compared using five kinds of forecasting methods;the Joinpoint linear regression had the best accuracy at 88.75%,followed by GM(1,1),linear regression,the dynamic series,and exponential smoothing at 88.72%,88.69%,87.79%,and 87.28%,respectively.Prediction accuracy of the combination model derived from GM(1,1)and linear regression,with accuracy of 99%or more,was higher than that of the combination model from exponential smoothing and GM(1,1),with weight coefficients based on the variance inverse method and the mean square error inverse method,which had the best prediction effect of the four weight calculation methods.Lung cancer mortality was fitted using four kinds of forecasting methods:exponential smoothing,Joinpoint linear regression,linear regression,and dynamic series were 81.74%,74.27%,72.54%,and 63.03%accurate,respectively.Prediction accuracy of the combination model of exponential smoothing and Joinpoint linear regression was higher than that of the combination model derived from exponential smoothing and linear regression;weight coefficients based on the arithmetic average and mean square error inverse method,which had the best prediction effect of the four weight calculation methods in both combination models.Age-specific death rates(ASDR)of cancer,lung cancer,liver cancer,and esophageal cancer were fitted using Joinpoint regression,which had prediction accuracy of 89.92%,89.70%,83.92%,82.21%,respectively.ASDR for cancer in generalhad the best fit accuracy,follow by lung cancer.In short,cancer mortality increased in the Jinchang Cohort and cancers were associated with high case-fatality rates and a heavy economic burden.In terms of harm to health,lung cancer,gastric cancer,liver cancer,and esophageal cancer are the key cancers in need of intervention.Cancer mortality prediction research showed that dynamic series is suitable for data with a geometric increase or decrease,linear regression is suitable for linear data showing steady growth during the observation period,the grey model is suitable for short sequences of data with an implied index law in the observation period,exponential smoothing is suitable for data with fluctuations in the forecast period;different data are best predicted using different models. |
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