Lung cancer in HK in 2002–2021: Increasing burden, survival improves but remains low

The University of Hong Kong’s (HKU) comprehensive analysis of lung cancer trends in Hong Kong between 2002 and 2021 reports an increase in crude incidence, a decline in age-standardized incidence, and an increase in survival rates, which, however, remained <40 percent at 5 years.   

The descriptive epidemiology study used a retrospective cohort of lung cancer patients from Hong Kong’s territory-wide electronic medical database, Clinical Data Analysis and Reporting System (CDARS), which included 87,259 incident cases between 2002 and 2021. [Lancet Reg Health West Pac 2024;doi:10.1016/j.lanwpc.2024.101030]

The number of annual incident lung cancer cases increased from 3,708 to 5,211 between 2002 and 2021. More than 60 percent of all incident cases were male, and close to 80 percent of all incident cases were aged ≥60 years. The percentage of male incident cases gradually decreased over the years, from 67.6 percent in 2002 to 59.8 percent in 2021.

“Lung cancer incidence in males showed a decreasing trend over the years, while the incidence in females remained stable,” noted the researchers. “Such disparity could be reflective of the change in smoking habits. Over the past decades, tobacco control legislation, increased tobacco tax and enforcement of no-smoking areas successfully reduced the number of prevalent smokers in Hong Kong. This reduction was particularly prominent in males, whose smoking prevalence decreased from 39.7 percent in 1982 to 18.1 percent in 2019, while it remained at around 4 percent in females.” [https://www.taco.gov.hk/t/english/infostation/infostation_sta_01.html]

The crude lung cancer incidence (per 100,000 persons) increased from 55.0 in 2022 to 70.3 in 2021. Age-standardized incidence (per 100,000 persons), on the other hand, decreased from 42.9 to 33.2 during the same time period, suggesting that an ageing population was a key factor in the increasing disease burden.

The 1-year and 5-year survival rates showed an increasing trend between 2004 and 2021 across sex, age and comorbidity groups. “The landmark discovery of EGFR as a targetable oncogene and use of EGFR tyrosine kinase inhibitors have significantly improved survival of advanced-stage non-small-cell lung cancer [NSCLC] patients harbouring corresponding mutations. More recently, PD-1/PD-L1 inhibitors provided an additional effective treatment option. At the same time, the improved survival brought about by the introduction of genetic testing in 2009 and the approval of immunotherapy for NSCLC in 2015 in Hong Kong could have contributed to the upward shift in lung cancer prevalence since 2016–2017,” commented the researchers. [N Engl J Med 2009;361:947-957; N Engl J Med 2020;383:640-649]

Females consistently had higher survival rates across the study period – their 1- and 5-year survival rates increased from 38.4 percent and 17.0 percent in 2004 to 67.0 percent and 35.2 percent in 2021, respectively, while respective male 5-year survival rates increased from 32.6 percent and 14.0 percent to 49.3 percent and 22.0 percent during the same period. “As never-smokers have better lung cancer survival than ex-smokers and current smokers, better survival in females could be reflective of the lower prevalence of female smokers,” suggested the researchers. [Ann Am Thorac Soc 2016;13:58-66]

“Although both short- and long-term survival rates showed improvement over the years, they remained low, highlighting the potential need for interventions [such as a lung cancer screening programme],” concluded the researchers. [N Engl J Med 2011;365:395-409; N Engl J Med 2020;382:503-513]