In a major reality check for lung cancer screening advocates, adherence rates in the real world are a far cry from the achievements seen in RCTs such as the NELSON and NLST trials.
A systematic review and meta-analysis of the evidence, comprising 19 US studies and almost 17,000 participants, has found an overall adherence rate of 55% across all follow-up periods.
According to the study published in JAMA Network Open, this rate compares unfavourably with impressive adherence rates of 90% and 94% respectively, seen in the two pivotal RCTs.
The systematic review excluded RCTs but included other prospective and retrospective studies where people at any level of risk of lung cancer entered a screening program and continued beyond their baseline low-dose CT.
The meta-analysis found the pooled rate for adherence was 30% in studies with screening at 12-month intervals, 70% in studies with 15-month intervals and 68% in studies with 18-month intervals.
It found current smokers were less likely to adhere to screening compared with former smokers (OR, 0.70; 95% CI, 0.62-0.80).
White race (OR, 2.0; 95% CI, 1.6-2.6), older age (OR, 1.4; 95% CI, 1.0-1.9) and higher educational attainment (OR, 1.5; 95% CI, 1.1-2.1) were factors associated with increased adherence.
“Given the overall low rates of cancer screening adherence within the US population and among high-risk individuals, it is not surprising that LCS adherence was lower than that seen within the controlled setting of clinical trials,” the study said.
The investigators said that uptake of screening for bowel cancer (68.8%) and breast cancer (70%) in the US were the result of the tests being available and recommended for many years.
“In contrast, LDCT for LCS is a relatively nascent field with most intervention efforts still focusing on increasing uptake and acceptability among patients and practitioners rather than promoting the importance of annual adherence.”
They said that stigma associated with lung cancer might also be a factor hindering higher screening rates.
“Prior work suggests that lung cancer stigma is a multilayered issue that spans individual and societal levels and includes placing blame on the individual for smoking as well as public attitudes and policies.”
“Furthermore, patients have reported feeling as though some health care professionals do not understand how their smoking was affected by the culture and period in which they have lived.”
The investigators, led by Dr Maria Lopez-Olivo from the MD Andersen Cancer Centre, said their findings had implications for lung cancer screening recommendations.
“Interventions should be directed toward increasing LCS adherence among several key groups: current smokers, patients of races other than White, and patients with lower levels of education.”
They also noted that data was needed on adherence with diagnostic testing among patients with abnormal scan results and adherence with curative treatment for those diagnosed with a stage I or II cancer.