The incidence rate of lung cancer began climbing in women not long after CT lung screening began in China, but lung cancer mortality rates have yet to fall. And no effect has been seen yet in men, according to an article published in the June issue of Lung Cancer.
Following the release of the U.S. National Lung Screening Trial (NLST) in 2011, numerous policymakers and public health experts in China have pushed for the institution of CT lung screening nationwide. Their efforts have led to a sharp increase in the availability of CT lung screening -- especially in major cities -- which, in turn, has likely had an effect on overall cancer incidence and mortality rates.
In the current study, co-author Ying Zheng from Fudan University and colleagues investigated the population-based changes to lung cancer incidence and mortality from 2005 to 2014 in the city of Shanghai. They acquired their data from the Shanghai Cancer Registry, the longest standing official cancer registry in China (Lung Cancer, April 2019, Vol. 132, pp. 114-118).
Upon analyzing the data, the researchers discovered an overall increase in the incidence of lung cancer in women from 2005 to 2014, with most of the increase occurring after the implementation of CT lung screening in 2011. In contrast, lung cancer incidence stayed nearly uniform in men within the same timeframe.
To be specific, the lung cancer incidence rate in women consistently remained at around 17 cases per 100,000 individuals between 2005 and 2010 but increased significantly after that year, starting at 18.69 cases per 100,000 individuals in 2011 and reaching 25.82 in 2014.
However, the team found no notable reductions in lung cancer mortality rates for either men or women. The overall annual percent changes in lung cancer mortality were decreases of 1.71% for men and 1.96% for women. Neither of these changes was statistically significant.
| Lung cancer incidence and mortality rates in Shanghai, China | ||||||
| Rate per 100,000 people | 2005 | 2011 | 2014 | |||
| Men | Women | Men | Women | Men | Women | |
| Lung cancer incidence | 44.46 | 17.6 | 42.51 | 18.69 | 45.38 | 25.82 |
| Lung cancer mortality | 38.19 | 13.61 | 36.07 | 12.69 | 34.64 | 11.95 |
The researchers further stratified their analysis by location (urban versus rural). For example, they noticed that in a representative urban district known as Xuhui, the incidence rate of lung cancer hardly changed from 2005 to 2011. Yet the rate rose by a statistically significant degree from 2011 to 2014 (with an annual percentage change of 19.84%) after the establishment of several CT lung screening programs.
The incidence rate also increased in women living in the rural district of Songjiang, but the increase was gradual throughout the entire period examined and was not characterized by a dramatic surge in 2011. The differences in trend between incidence rates in the urban and rural districts could be explained by the limited availability of CT lung screening exams in rural districts -- decreasing opportunities to detect lung cancer in these areas, according to Zheng and colleagues.
"Results from this study suggested a higher future burden of overall lung cancer among women than among men as younger cohorts age, which further underscores the need to intensify prevention and screening measures to decrease lung cancer incidence among young women," the authors wrote. "Furthermore, our findings highlighted the importance of continued monitoring of sex-specific risks of lung cancer."
