A study using a 5-year low-dose computed tomography (LDCT) screening protocol showed good adherence and patient survival outcomes in persons at high risk of developing lung cancer, according to investigators of the Continuous Observation of Smoking Subjects (COSMOS) study. Fewer patients required further diagnostic follow-up with a minimal number of incorrect diagnoses, compared with the National Lung Cancer Screening Trial (NLST) and other studies.

The COSMOS study screened 5,203 asymptomatic persons who were 50 years and older with a 20 or more pack years smoking history, with 79% of participants remaining on the study for 5 years and 6.4% required a procedure other than the annual LDCT. The screened participants went on to other diagnostic procedures (CT, PET, or surgery) to verify suspected lung cancer, or were rescreened annually for 4 years, based on the study criteria. In addition, all participants were clinically followed for a median of 5.2 years.

Due to the size and the long follow-up, the study encompassed 23,116 person-years of observation. Primary lung cancer was diagnosed in 175 patients and 78% of cases were localized disease. The overall detection rate was 0.76 cases of lung cancer per 100 person-years. Of the 204 invasive diagnostic procedures undertaken, 29 were benign for lung cancer, 34 had minor complications, 12 had major complications, and one postoperative fatality was reported. In 14 cases, the lesions were not initially diagnosed as cancer, but were later determined to be cancer on subsequent yearly screening, and 87% of cases were treated with intent to cure. Overall 5-year survival was 78%. The study was led by Dr. Giulia Veronesi, from the Department of Thoracic Surgery, European Institute of Oncology in Milan, Italy, and the results were reported in the Journal of Thoracic Oncology (doi:10.1097/JTO. 0000000000000200).

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The 5-year survival rate for lung cancer diagnosed early is 50%; however, it is significantly less (4%) after distant metastasis. Recent results from the NLST showed mortality was reduced to 20% with LDCT compared with chest radiography, verifying that early detection can reduce the number of deaths from lung cancer. However, few studies have rigorously assessed the diagnostic performance, invasiveness, and side effects of LDCT screening protocols with enduring follow-up.

“The results of the COSMOS workup protocol for indeterminate nodules detected with LDCT screening are encouraging, particularly the low recall and delayed diagnosis rates as well as the good long-term survival,” explained Veronesi. “However, the workup can still be improved, possibly by tailoring the screening interval to the risk of the [person] being screened using a risk evaluation algorithm that will hopefully also include in the near future molecular markers like a microRNA expression signature in serum.”