A Novel Approach to Modeling and Forecasting Cancer Incidence and Mortality Rates through Web Queries and Automated Forecasting Algorithms: Evidence from Romania

Abstract

Cancer remains a leading cause of worldwide mortality and is a growing, multifaceted global burden. As a result, cancer prevention and cancer mortality reduction are counted among the most pressing public health issues of the twenty-first century. In turn, accurate projections of cancer incidence and mortality rates are paramount for robust policymaking, aimed at creating efficient and inclusive public health systems and also for establishing a baseline to assess the impact of newly introduced public health measures. Within the European Union (EU), Romania consistently reports higher mortality from all types of cancer than the EU average, caused by an inefficient and underfinanced public health system and lower economic development that in turn have created the phenomenon of "oncotourism". This paper aims to develop novel cancer incidence/cancer mortality models based on historical links between incidence and mortality occurrence as reflected in official statistics and population web-search habits. Subsequently, it employs estimates of the web query index to produce forecasts of cancer incidence and mortality rates in Romania. Various statistical and machine-learning models-the autoregressive integrated moving average model (ARIMA), the Exponential Smoothing State Space Model with Box-Cox Transformation, ARMA Errors, Trend, and Seasonal Components (TBATS), and a feed-forward neural network nonlinear autoregression model, or NNAR-are estimated through automated algorithms to assess in-sample fit and out-of-sample forecasting accuracy for web-query volume data. Forecasts are produced with the overperforming model in the out-of-sample context (i.e., NNAR) and fed into the novel incidence/mortality models. Results indicate a continuation of the increasing trends in cancer incidence and mortality in Romania by 2026, with projected levels for the age-standardized total cancer incidence of 313.8 and the age-standardized mortality rate of 233.8 representing an increase of 2%, and, respectively, 3% relative to the 2019 levels. Research findings thus indicate that, under the no-change hypothesis, cancer will remain a significant burden in Romania and highlight the need and urgency to improve the status quo in the Romanian public health system.

Keywords: ARIMA; Google Trends; NNAR; Romania; TBATS; cancer; forecasting; incidence; modeling; mortality.

Figure 1

Most common queries related to the search term “cancer”: worldwide (April 2017–March 2022). Source of data: Google Trends. Estimation results using the “gtrendsR” package [19] in R software.

Figure 2

Internet search interest for “cancer” at the world level: (April 2017–March 2022). Source of data: Google Trends. Map is based on estimation results and uses the packages “gtrendsR” [19] and “tmap” [21] in R software.

Figure 3

Trends in cancer mortality rates in selected CEE countries (2011–2018). Estimation results. Plot created in R software (“ggplots” function). Source of data: Eurostat.

Figure 4

Trends in age-standardized cancer incidence and mortality rates in Romania (2010–2019) (panel a); join-points in cancer incidence rate (panel b). Source of data: Romanian Ministry of Health (2021) [32]. Chart in panel (a) is produced in Datawrapper. Chart in panel (b) is produced with the “ggplot” function in R software; join-point regression analysis is performed with the “segmented” package within R software.

Figure 4

Trends in age-standardized cancer incidence and mortality rates in Romania (2010–2019) (panel a); join-points in cancer incidence rate (panel b). Source of data: Romanian Ministry of Health (2021) [32]. Chart in panel (a) is produced in Datawrapper. Chart in panel (b) is produced with the “ggplot” function in R software; join-point regression analysis is performed with the “segmented” package within R software.

Figure 5

The integrated framework for modeling and forecasting cancer incidence and mortality rates.

Figure 6

The relationship (linear—blue line, polynomial—orange line) between related web queries and the age-standardized cancer incidence rate in Romania (panel a). The relationship (linear—blue line, polynomial—orange line) between related web queries and the age-standardized cancer mortality rate in Romania (panel b). Source of data: Romanian Ministry of Health [32]. All estimations were performed in R software; plots were created in R software (i.e.,“ggplot” function).

Figure 7

Forecasted trend over April 2022–March 2026 (48 months) for web queries for the term “cancer” in Romania issued with NNAR (12,6). Source: estimation results. Model information: average of 20 networks, each of which is a 12-6-1 network with 85 weight options.