Results Summary
What was the research about?
Lung cancer is the second most common cancer in the United States. Among lung cancers, 80 to 85 percent are of the type called non-small cell lung cancer, or NSCLC. When doctors find NSCLC early, they can treat it by removing all or part of the lung. Imaging tests then look for signs of the cancer coming back or a new lung cancer forming. These tests include chest CT scan or X-ray. Guidelines vary in their advice to doctors about how often patients should get these imaging tests. Guidelines may recommend imaging tests every 3, 6, or 12 months after surgery.
The research team wanted to learn if getting imaging tests every 3, 6, or 12 months after surgery helps patients live longer. The team also wanted to see if more frequent testing helps doctors detect returning or new cancers earlier. The team compared medical records of patients who received imaging tests on different schedules.
What were the results?
Compared with getting an imaging test for NSCLC every 12 months, getting an imaging test more often—every 3 or 6 months—didn’t make it more likely that patients would live longer after their surgery. More frequent imaging tests also didn’t improve how early doctors detected returning or new cancers.
Who was in the study?
The research team looked at medical records for 6,350 patients with NSCLC who had lung surgery and follow-up imaging tests. Of these, 66 percent had an early stage of NSCLC. The average patient age was 66, and 52 percent were men. In addition, 89 percent were white, 8 percent were black, and 3 percent were other races.
What did the research team do?
The research team looked at patients’ medical records from 2006 to 2007 and for up to five years after patients’ surgeries.
The team grouped patients’ records according to when they had their first imaging test: 3, 6, or 12 months after surgery. The research team used that timing as an indicator of how often the patients would get later imaging tests. Across these three groups, the team compared how many patients were alive five years after their surgery and if doctors detected returning or new cancers.
During the study, the research team worked with other cancer researchers and a group of patients who had lung or other types of cancer. This group helped the research team design the study and analyze the results.
What were the limits of the study?
The research team grouped patients by when they received the first imaging test. But patients may have had imaging tests more or less often after the first test. When looking at how long patients lived, the team included patients who died of any cause, not only lung cancer.
The information from this study is from patients treated in 2006 to 2007. Future research could look at more recent patient records with current treatment patterns.
How can people use the results?
Patients with lung cancer and their doctors could use these results when discussing how often to get imaging tests after surgery.
Professional Abstract
Objective
To compare overall survival and recurrence or new primary cancer outcomes in patients with non-small cell lung cancer (NSCLC) followed at different intervals using surveillance imaging after surgery
Study Design
| Design Elements | Description |
|---|---|
| Design | Observational: cohort study |
| Population | 6,350 patients in the National Cancer Database with clinical stage I–III NSCLC |
| Interventions/ Comparators |
Surveillance imaging (CT scan or chest X-ray) every 3, 6, or 12 months |
| Outcomes |
Primary: overall survival Secondary: time to cancer recurrence or new primary cancer |
| Timeframe | Up to 5-year follow-up for primary outcome |
This retrospective cohort study compared the overall survival and time to cancer recurrence or new primary cancer in patients with NSCLC who underwent surveillance imaging every 3, 6, or 12 months following surgery.
The study included medical records of 6,350 patients in the National Cancer Database with stage I–III NSCLC diagnosed in 2006 to 2007 who underwent surgery to remove all or part of a lung and had follow-up surveillance imaging. Of these patients, 66% had stage I NSCLC. The average patient age was 66, and 52% were male. In addition, 89% of patients were white, 8% were black, and 3% were other races.
The research team examined postsurgery data, including surveillance imaging and mortality, for patients who had five years of follow-up. Because patients often do not follow prescribed surveillance intervals and providers may change prescribed frequency based on imaging results, the research team used the time to the first postsurgery surveillance imaging as an indicator of a patient’s surveillance frequency plan. The team placed patients into three surveillance-imaging-intensity groups: 3-month; 6-month; and 12-month surveillance. More than 60% of these patients continued to have imaging tests at the original interval.
After controlling for age, sex, comorbidities, histology, pathological stage, and surgical procedure, the research team measured patients’ survival across follow-up groups. The team also compared time to recurrence or new primary cancer among the three groups.
A group of researchers from academic institutions, representatives from nonprofit cancer trial organizations, and 24 cancer survivors, 5 of whom had lung cancer, helped shape the study’s design, selection of outcomes, and data analysis.
Results
- Overall survival: There was no association between surveillance-imaging intervals and improved survival. The hazard ratio for survival for 6-month surveillance relative to 3-month was 1.10 (95% confidence interval [CI]: 0.97, 1.25), and the hazard ratio for survival for 12-month surveillance relative to 3-month was 1.00 (95% CI: 0.84, 1.18).
- Time to recurrence or new primary cancer: There was no association between surveillance-imaging intervals and time detection of recurrence or new primary cancer. The hazard ratio for time to recurrence or new primary cancer for 6-month surveillance relative to 3-month was 1.00 (95% CI: 0.84, 1.19; p=0.97), and the hazard ratio for time to recurrence for 12-month surveillance relative to 3-month was 0.94 (95% CI: 0.73, 1.21; p=0.65).
Limitations
The research team assumed the first surveillance-imaging time reflected the intended surveillance interval, which may not correctly classify the surveillance groups. If the team had looked at NSCLC-specific mortality rather than overall mortality, they may have found different results. The data used in this study are from patients treated in 2006 to 2007; treatment patterns may have changed in recent years.
Conclusions and Relevance
This study found no association between more frequent surveillance imaging after surgery for NSCLC and improved overall survival or reduced time to recurrence or new primary cancer occurrence. These results suggest that 12-month or 6-month surveillance-imaging plans for postsurgery patients with NSCLC are appropriate.
Future Research Needs
Future research could reexamine outcomes using more recent data.
Final Research Report
View this project's final research report.
Journal Citations
Results of This Project
Related Journal Citations
Peer-Review Summary
Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also assesses how the project addressed PCORI’s Methodology Standards. During peer review, experts read a draft report of the research and provide comments about the report. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. These reviewers cannot have conflicts of interest with the study.
The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve descriptions of the conduct of the study or to clarify the connection between results and conclusions. Sometimes, awardees revise their draft reports twice or more to address all of the reviewers’ comments.
Peer reviewers commented and the researchers made changes or provided responses. Those comments and responses included the following:
- Reviewers expressed concern that there remains insufficient evidence of the utility of surveillance after treatment of lung cancer. They stated that it would be more important for researchers to investigate this question first, before studying the relationship of surveillance intensity to lung cancer outcomes. In response, the researchers cited studies demonstrating a reduction in cancer-related mortality when patients received some sort of post-treatment surveillance but acknowledged that they did not design the current study to evaluate whether any surveillance is better than no surveillance.
- Reviewers noted the potential for selection bias in forming the study cohort in that surveillance imaging, by definition, takes place in patients who are cancer-free. Thus, for patients to participate in annual surveillance imaging they would need to be cancer-free for one year, whereas for patients to participate in surveillance imaging every 3 months, they would have to be cancer-free for only 3 months. Thus, the patients who were cancer-free long enough to participate in annual surveillance were less likely to ever have a recurrence than the patients who participated in 3-month surveillance. The researchers acknowledged this limitation but attempted to reduce this bias by only comparing patients who remained disease-free for the same period of time in both groups.