New research has revealed why some lung cancers are undetected by radiograph and helped to identify the type of people who may be at risk of this form of the disease.
The findings will be presented today (Monday 3 September 2012) at the European Respiratory Society's Annual Congress in Vienna.
There has been no significant reduction in lung cancer mortality rates in recent years. Chest radiographs can be used to screen for lung cancer. However, these aren't always effective and it appears that some cancers are later diagnosed even though individuals have received a negative chest radiograph within the previous 12 months.
The reason for this could be due to human error with the cancer being missed on the review of the radiograph, due to the cancer being undetectable by this form of screening technique, or because the cancer developed so rapidly that it both initiates and becomes evident in the time interval between screening tests.
Little is known about this form of lung cancer that is not detected by screening chest radiograph, which is referred to as an interval cancer. To improve the understanding of this type of the disease, researchers aimed to analyse the type of people who developed this cancer and the characteristics of the disease.
The research used data from a national screening trial in the USA. It followed 77,445 participants who were screened at the start of the study and then annually for either 2 or 3 years depending on their smoking status.
A total of 450 people were diagnosed with lung cancer during the years of chest radiograph screening, of which 152 were initially not spotted by the radiograph. Out of this group, 35% of lung cancers not initially identified on the radiograph were spotted when it was re-reviewed. The remaining 65% of this group therefore had 'true interval cancer' which was not detected on the initial screening, or the second review.