Estimation of the adult population at high risk of developing lung cancer in the European Union

Highlights

• Between 17 and 34 million citizens in the EU are at high risk of lung cancer.

• Between 10 and 25% of smokers in the EU are at high risk of lung cancer.

• The proportion of former smokers at high risk is not negligible.

• In most countries, the proportion of men at high risk is higher than in women.

Abstract

Background Lung cancer mortality accounts for over 266,000 deaths in the European Union (EU) every year, most of them attributed to smoking. The aim of this study was to estimate the prevalence of the adult population at high risk of developing lung cancer in the EU in 2014.

Methods This is a cross-sectional study. We used data from the Special Eurobarometer 429 (n = 27,801). The fieldwork was conducted between November-December 2014. High risk of lung cancer was defined using the criteria of the National Lung Screening Trial (NLST) and the Dutch-Belgian Lung Cancer Screening Trial (NELSON).

Results One out of ten smokers (11.6% of men and 9.6% of women) according to NLST criteria and one out of four smokers (24.6% of men and 22.4% of women) according to NELSON criteria are currently at high risk of lung cancer in the EU. According to both criteria, the prevalence of former smokers at high risk of lung cancer is under 10%.

Conclusion Around 17 million citizens in the EU according to NLST criteria and 34 million according to NELSON criteria (around 4% and 8% of the adult population, respectively) are at high risk of developing lung cancer. Since the implementation of lung cancer screening programs still remains controversial, primary prevention activities should be encouraged.

Introduction

The impact of smoking on health is well known. Smoking is the major preventable risk factor of burden of disease, disability, and death [1], responsible for 7.1 million deaths worldwide per year [2]. Around 700,000 of these deaths, mainly related to a range of cancers and respiratory disorders, occur in the European Union (EU) [3].

Among the different types of cancer associated with smoking (e.g., lung, stomach, liver, urinary bladder), lung cancer, which is one of the deadliest [4], is caused eight out of ten times by smoking [5], a proportion very distant from that related to exposure to radon [6]. In absolute figures, over 266,000 people die from lung cancer in the EU each year [7], many of them prematurely. Besides, in women, the lung cancer mortality rate has been predicted to exceed the breast cancer mortality rate in Europe in 2017 [8], and for specific cohorts in some countries this situation is likely to occur in the near future [9].

The high mortality showed by lung cancer is usually the consequence of a late diagnosis, frequently at stages III-IV, when prognosis is poorer. Overall, the estimated 5-year survival rate from diagnosis is very low (around 17%) [10] and this proportion has practically remained invariable for years. For this reason, in recent years, the implementation of lung cancer screening programs has been assessed in terms of cost-effectiveness [11] and net benefit in all-cause and lung cancer-specific mortality reduction [12]. Among lung cancer screening tests, X-ray with or without sputum cytology have not been recommended since they have been proved not to decrease lung cancer mortality. However, an annual low-dose computed tomography (CT) has been recommended for high risk groups by a number of organizations since low-dose CT can reduce lung cancer mortality and all-cause mortality [13].

This positive assessment on the implementation of low-dose CT screening mainly arises from the National Lung Screening Trial (NLST), a US multicentric randomized trial where a decrease of 20% in the mortality attributable to lung cancer, as well as an all-cause mortality reduction of 6.7%, were observed in the group undergoing low-dose CT compared with the group undergoing chest X-ray [14]. In Europe, different randomized trials have been carried out to assess the effectiveness of the low-dose CT, such as the Dutch-Belgian Randomized Lung Cancer Screening Trial (NELSON) [15], which compared low-dose CT versus no intervention in a protocol of one, two, four and six and a half years and of which interim results showed high specificity and sensitivity [16], although definitive results are still awaited. Nevertheless, thus far, low-dose CT has neither been implemented as a high risk (i.e., selective) screening program in the EU nor recommended by the Council of the EU, contrary to breast, cervical and colorectal cancer, for which official recommendations were already published in 2003 [17]. Besides, there is ongoing debate in the scientific community around the potential benefits and harms related to low-dose CT screening programs [18,19].

To assess the potential impact of the implementation of low-dose CT lung cancer screening programs in the EU in terms of beneficiary population, a preliminary estimation of the population at high risk of developing lung cancer should be provided. The aim of this study was to determine the prevalence in 2014 of the adult population (≥15years) at high risk of developing lung cancer in the EU according to NLST and NELSON criteria.