Burden of cancer and changing cancer spectrum among older adults in China: Trends and projections to 2030

1

Introduction

Over the past 30 years, there were rapid increases in the incidence of lung, breast, colorectal, and prostate cancer, and high incidence of liver, stomach, esophageal, and cervical cancer in China [12] . The rising cancer burden in China is likely due to environmental changes associated with industrialization and the adoption of a western lifestyle [3] . However, these factors do not fully explain the cancer trend. For instance, the crude cancer mortality rate increased from 108.3 per 100,000 in 1990–1992–170.1 per 100,000 in 2015, while the age-standardized mortality rate decreased from 94.4 per 100,000 to 77.9 per 100,000 [3] . The opposite trends suggest that the rise of cancer mortality could be attributable to the aging population, as the incidence of most cancers increases dramatically after age 65 [4] . An analysis of the 2012 Global Cancer Observatory suggested that the incidence rate of all cancer among adults aged 65 and above was 1169 per 100,000 in China [5] , much higher than the rate for adults aged below 65 years. In addition to population aging, cancer incidence and mortality rates may also change over time. As the proportion of older adults aged 60 years and above in China has increased from 13.3% in 2010 to 18.7% in 2020, and is projected to reach 35% by 2050, the cancer burden would increase accordingly [6] . However, few studies have specifically examined how population aging and changing cancer rates impact the future burden of cancer in older Chinese adults and its implications for China’s healthcare system.

The joinpoint regression model is frequently used to describe cancer trends [7] . Traditional methods for trend analyses, such as linear regression or time series analysis, assume one model for all data. However, a single model is not flexible enough to capture non-linear trends. In the joinpoint regression, data are divided into several sections, and a linear model is fitted for each section to reveal general trends and turning points [8] . Therefore, it has been widely used in modeling the trends in cancer and other chronic diseases [9] .

This study aimed to 1) estimate the trends in cancer incidence and mortality rates between 2006 and 2015 among adults aged 60 years or older in China using the joinpoint regression, and 2) forecast the number of new cancer cases and deaths per year till 2030 among older Chinese adults based on population projection and trend in cancer rates. These analyses have great implications for the planning of cancer prevention strategies and prioritization of cancer research in China.