Lung cancer screening of low-risk women leads to overdiagnosis: JAMA
Taiwan: Low-dose computed tomographic (LDCT) screening of nonsmoking Asian women is associated with a considerable lung cancer overdiagnosis, reveals a recent study in JAMA Internal Medicine.
"Unless randomized controlled trial can show value to low-risk groups, LDCT screening should be offered only to heavy smokers," Wayne Gao, College of Public Health, Taipei Medical University, Taipei City, Taiwan, and colleagues wrote in their study.
With a decline in smoking in many developed countries, the proportion of lung cancers in nonsmokers will increase. This shift may create substantial pressure for further expanding lung cancer screening to lower-risk groups. Considering this, the researcher's team aimed to determine the association of lung cancer incidence with the promotion of screening in a largely nonsmoking population in a population-based ecological cohort study of stage-specific lung cancer incidence.
The researchers used the Taiwan Cancer Registry to identify women diagnosed with lung cancer from January 1, 2004, to December 31, 2018. Smoking prevalence among Taiwanese women has been less than 5% since 1980. Data analysis was performed from February 13, 2020, to November 10, 2021.
The main outcome was a change in stage-specific lung cancer incidence. An effective cancer screening program will increase the incidence of early-stage cancer and in addition, will also decrease the incidence of cancer presenting at a late stage.
The study revealed the following findings:
- A total of 57 898 women were diagnosed with lung cancer in a population of approximately 12 million Taiwanese women.
- After the introduction of LDCT screening, the incidence of early-stage (stages 0-I) lung cancer in women increased more than 6-fold, from 2.3 to 14.4 per 100 000 population (absolute difference, 12.1) from 2004 to 2018.
- There was no change, however, in the incidence of late-stage (stages II-IV) lung cancer, from 18.7 to 19.3 per 100 000 (absolute difference, 0.6).
- Because the additional 12.1 per 100 000 early-stage cancers were not accompanied by a concomitant decline in late-stage cancers, virtually all the additional cancers detected represent overdiagnosis.
- Despite stable mortality, 5-year survival more than doubled from 2004 to 2013, from 18% to 40%, which is arguably the highest lung cancer survival rate in the world.
The researchers concluded, "Lung cancer screening in a largely nonsmoking population was associated with considerable overdiagnosis and spuriously high 5-year survival rate."
Reference:
Gao W, Wen CP, Wu A, Welch HG. Association of Computed Tomographic Screening Promotion With Lung Cancer Overdiagnosis Among Asian Women. JAMA Intern Med. Published online January 18, 2022. doi:10.1001/jamainternmed.2021.7769
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