Age-period-cohort analysis of lung cancer mortality in China and Australia from 1990 to 2019

Abstract

Lung cancer (LC) is the leading cause of cancer death in China and Australia, the countries with different socioenvironmental contexts in the Western Pacific Region. Comparing the age-period-cohort effect on LC mortality (LCM) between the two countries can help plan interventions and draw lessons for countries in the region. We collected LCM estimates between 1990 and 2019 from the GBD 2019. Age-period-cohort modelling was applied to compute the net drift, local drift, cross-sectional age curve, longitudinal age curve, and the rate ratios (RRs) of period and cohort. China had a higher LC age-standardized mortality rate than Australia in 2019 (men: 58.10 [95% uncertainty interval (UI): 46.53, 70.89] vs. 30.13 [95% UI: 27.88, 32.31]/100,000 population; women: 22.86 [95% UI: 18.52, 27.52] vs. 17.80 [95% UI: 15.93, 19.34]/100,000 population). Period and cohort effects on LCM improved more markedly among Australian men (RR for period effect, from 1.47 [95% confidence interval (CI) 1.41, 1.53] to 0.79 [95% CI 0.75, 0.84]; RR for cohort effect, from 2.56 [95% CI 2.44, 2.68] to 0.36 [95% CI 0.11, 1.18]) and Chinese women (RR for period effect, from 1.06 [95% CI 1.01, 1.11] to 0.85 [95% CI 0.82, 0.89]; RR for cohort effect, from 0.71 [95% CI 0.65, 0.78] to 0.51 [95% CI 0.26, 1.03]) during the study period and birth cohort. The LCM in Chinese population aged 65 to 79 and Australian women aged 75 to 79 increased. Smoking and particulate matter (PM) contributed most to LCM in China, while smoking and occupational carcinogens contributed most in Australia. Decreasing period and cohort risks for LCM attributable to smoking and PM were more remarkable in Australia than in China. The LCM attributable to occupational carcinogens was higher in Australia than in China, particularly for those aged 60 to 79. Vigorous tobacco and PM control, which brought a substantial decline in LCM in Australia, may help reduce LCM in China. Australia should highlight LC prevention among people with occupational exposure. Chinese aged ≥ 65 and Australian women aged ≥ 75 should be the priorities for LC interventions.

Figure 1

Age-standardized mortality rate of lung cancer by sex in China and Australia, 1990 to 2019.

Figure 2

Age-specific mortality rates of lung cancer by period and sex in China and Australia, 1990 to 2019. The study period was organized into 5-year periods from 1990–1994, 1995–1999, 2000–2004, 2005–2009, 2010–2014, to 2015–2019. (a1,b1) Reveal that lung cancer mortality rate increased among men and women aged 65 or older in China over the study period (P < 0.001). (a2) Shows that in Australian men, lung cancer mortality rate decreased over the study period in all age groups (P < 0.001). (b2) Shows that lung cancer mortality rate increased among Australian women aged 70 or older (P < 0.001). Cross-sectional age curves present the expected age-specific rates in reference period, i.e., 2000 to 2004, after adjusting for cohort effects.

Figure 3

Cohort-specific mortality rates of lung cancer by age and sex in China and Australia, 1990 to 2019. Data of lung cancer mortality were grouped into 17 successive birth cohorts which include those born between 1913–1917 and 1993–1997, and 12 age groups between 20–24 and 75–79. (a1) Shows that lung cancer mortality rate increased over birth cohorts among Chinese men aged between 60 and 79, indicating a higher rate in more recent birth cohorts among these age groups. On the contrary, there was a decreasing trend over birth cohorts among Chinese men aged between 20 and 59, indicating a lower mortality rate in more recent birth cohorts in these relatively young age groups. (a2) Shows that lung cancer mortality rates decreased over birth cohorts in all age groups of Australian men. This suggests a lower risk of lung cancer death in more recent birth cohorts across all ages. (b1) Shows that the trend of age-specific lung cancer mortality rates with birth cohort in Chinese women was similar to that in Chinese men. (b2) Shows that Australian women aged between 70 and 79 have experienced an increasing trend over birth cohorts, while those aged between 20 and 69 have experienced a decreasing trend over birth cohorts (P < 0.001 for all).

Figure 4

Net drift and local drift values for lung cancer mortality rate by sex in China and Australia, 1990 to 2019. Net drift represents the annual percentage change in age-adjusted lung cancer mortality rate over time, which indicates the overall log-linear trend by period and cohort. Local drifts represent the annual percentage changes of lung cancer mortality rate in each age group over time, which indicate the age-specific log-linear trends by period and cohort. (a) Shows that the net drift values were negative among both genders in the two countries, with Australian men having a significantly lower value than Chinese men. This indicates that the overall lung cancer mortality rate decreased more strikingly in Australian men than their Chinese counterparts. (b) Shows that the difference in the net drift value between Chinese women and Australian women was nonsignificant. The local drift values were positive in Chinese men and women aged between 65 and 79, suggesting lung cancer mortality rates were increasing in these age groups. In Australia, lung cancer mortality rates were decreasing with the exception of women aged between 75 and 79 (local drift values were positive in women of these age groups).

Figure 5

Parameter estimates of age, period, and cohort effects on lung cancer mortality in China and Australia, 1990 to 2019. (a1,b1) show the longitudinal age curves of lung cancer mortality (per 100,000 person-years) and the 95% CIs among men and women in the two countries, respectively, representing the expected age-specific rates in reference cohort adjusted for period effect. (a2,b2) show the rate ratios of lung cancer mortality in different periods (period effects) relative to the reference period (2000–2004) adjusted for age and cohort effect, and the 95% CIs among men and women in the two countries, respectively. (a3,b3) show the rate ratios of lung cancer mortality in different cohorts (cohort effects) relative to the reference cohort (1953–1957) adjusted for age and period effect, and the 95% CI among men and women in the two countries, respectively.