Long-term findings from an international study of annual low-dose computed tomography (CT) screening demonstrate 81 percent survival rates at 10 and 20 years after initial primary lung cancer diagnosis for patients with a median 43-pack-year smoking history.
For the study, recently published in Radiology, researchers examined 20-year outcomes for 1,257 participants who were diagnosed with a first primary lung cancer via low-dose CT screening. These participants were drawn from a cohort of 89,404 for an international, prospective multicenter study referred to as the International Early Lung Cancer Action Program (I-ELCAP).
Based on 484 participants diagnosed with an initial primary lung cancer (with 85 percent having stage 1 lung cancer), the authors of the first I-ELCAP study in 2006 reported a 10-year lung-cancer specific survival rate of 81 percent.
Out of the 1,257 participant-cohort in the current study, the most common diagnoses were adenocarcinoma (67.1 percent), squamous cell carcinoma (13.4 percent) and small cell carcinoma (6.5 percent), according to the researchers. Nearly 80 percent of the cohort underwent surgical resection while the remaining participants (20.6 percent) had chemotherapy (9.1 percent), stereotactic body radiation therapy (SBRT) (6.1 percent), concurrent radiation therapy and chemotherapy (1.9 percent, or other treatments (3.5 percent). The median age of the cohort was 66 at the time of diagnosis and the mean smoking history was 43 pack-years, according to the study.
The researchers found that the 20-year survival rate for this cohort was also 81 percent.
Here one can see two low-dose computed tomography (CT) scans, taken six years apart, for a 60-year-old female who was a current smoker with a 30-pack-year smoking history prior to her baseline CT exam (A). A 4.5 mm solid nodule was diagnosed on her sixth annual CT exam (B). In retrospect, the nodule was also apparent on the baseline CT exam at 2.0 mm. The patient was ultimately diagnosed with a mixed subtype adenocarcinoma. (Images courtesy of Radiology.)
“The estimated cure rate of 80% reported in 2006 based on the 10-year survival of 484 participants in I-ELCAP diagnosed with a first primary lung cancer under annual low-dose CT screening has persisted after 20 years of follow-up in the expanded I-ELCAP cohort of 1257 participants and enables us to confirm the benefit of annual low-dose CT screening,” wrote Claudia I. Henschke, Ph.D., M.D., a professor of radiology in the Department of Diagnostic, Molecular and Interventional Radiology at the Icahn School of Medicine at Mount Sinai in New York, N.Y., and colleagues.
The study authors also noted similar lung-cancer specific survival rates regardless of smoking history. Henschke and colleagues pointed out an 85 percent survival rate for those who had less than 10 pack-years of smoking history; an 83 percent survival rate for those with 10 to 29 pack-years; and a 79 percent survival rate for study participants who had at least a 30 pack-year smoking history.
Top Three Takeaways
- Long-term survival benefit. The study reveals that patients with a median smoking history of 43 pack-years who were diagnosed with primary lung cancer through annual low-dose CT screening demonstrated an 81 percent survival rate at both 10 and 20 years after diagnosis. This suggests that long-term benefits can be derived from this screening approach.
- Consistent survival rates across smoking history. Regardless of their smoking history, patients in the study showed similar lung-cancer specific survival rates. This indicates that low-dose CT screening is effective in improving survival outcomes for patients with varying levels of smoking exposure, including those with heavy smoking histories.
- Confirmation of CT screening benefit. The study's findings, including the 20-year survival rate of 81 percent, confirm the long-term benefit of annual low-dose CT screening for lung cancer. This strengthens the case for the continued use of this screening method to detect and manage lung cancer.
“After adjusting for sex and age, there was no evidence of a difference in the risk of lung cancer death among participants who had smoked for at least 30 pack-years when compared with participants who had a smoking history of less than 10 pack-years, including those who had never smoked ... and participants who had smoked for 10–29 pack-years … ,” added Henschke and colleagues.
(Editor’s note: For related content, see “CT News: American Cancer Society Issues Updated Lung Cancer Screening Recommendations,” “Study: AI Assessment of Chest CT May Predict Multiple Mortality Risks” and “Study Shows Significant Incidental Findings in Nearly 34 Percent of Lung Screening CT Exams.”)
In regard to study limitations, the researchers acknowledged variable compliance with the annual lung screening protocol and that less than half of the study cohort (556 out of 1,257 participants) had more than 10 years of follow-up CT exams. The study authors also pointed out that the long-term study did not fully recognize technological advances with CT and positron emission tomography (PET) that occurred during this time period.