Study overview
Metastatic non-small cell lung cancer (mNSCLC) is one of the most serious forms of lung cancer. It has long carried a very high risk of death, but treatment has changed dramatically over the past two decades. Chemotherapy, immunotherapy, and targeted therapies have made it possible to help many patients live longer and, in some cases, with fewer side effects than older regimens.
Even with these advances, it has been unclear how often older adults in the United States actually receive systemic treatment in everyday practice. This study used linked Surveillance, Epidemiology, and End Results (SEER) and Medicare data to look at treatment patterns among patients 65 years and older who were diagnosed with mNSCLC between January 2006 and December 2021.
The goal was not just to count how many people were treated, but also to understand which factors were linked to getting treatment. The researchers focused on issues that matter in real-world cancer care, including age, comorbidity burden, tumor histology, referral to an oncology specialist, Medicare coverage, biomarker testing, rural or urban residence, and race and ethnicity.
How the study was done
This was a population-based cohort study, meaning it followed a very large group of patients drawn from national cancer and insurance records rather than from a single hospital. That approach is especially useful for studying older adults, because it reflects what happens in routine care across different settings.
The main outcome was simple: whether a patient ever received systemic treatment after diagnosis. In cancer care, systemic treatment refers to medication that travels through the bloodstream and can affect cancer cells throughout the body. For mNSCLC, that can include chemotherapy, immunotherapy, and targeted therapy. These treatments are often chosen based on tumor biology, patient health, and personal goals of care.
Because some patients die very soon after diagnosis and may never have a realistic chance to start treatment, the researchers used a competing-risk statistical model. In plain language, this means they accounted for the fact that death can happen before treatment begins and can change the way treatment rates are measured over time.
Key findings
The study included 254,611 older adults with mNSCLC. The median age was 73 years, and just over half of the patients were men. Most patients were White, with smaller proportions of Black, Asian, Hispanic, and other or unknown racial groups.
Overall, 119,197 patients, or 46.8%, ever received systemic treatment. That means that more than half never received drug therapy for their metastatic cancer.
Timing mattered a great deal. Of the 100,367 patients who died within 90 days of diagnosis, only 13.2% received systemic treatment. By contrast, 69% of those who lived more than 90 days were treated. This pattern suggests that many patients were either too ill to start therapy, were diagnosed very late in the course of illness, or faced barriers to timely care.
Treatment rates improved only slightly from 2006 to 2021, despite the arrival of newer and often better-tolerated therapies during that period. In other words, the treatment landscape changed, but population-level use changed only modestly.
The strongest factor linked with treatment was referral to an oncology specialist. Patients who were referred had a hazard ratio of 2.5 for receiving systemic treatment, meaning they were far more likely to be treated than those without a referral. In practical terms, referral was associated with a 30.3% higher cumulative incidence of treatment at 180 days.
Biomarker testing was also important. Patients whose tumors were tested for biomarkers had a 17.8% higher cumulative incidence of treatment at 180 days. This makes clinical sense, because biomarker testing can identify patients who may benefit from targeted drugs or immunotherapy. In modern NSCLC care, testing often helps guide treatment decisions for markers such as EGFR, ALK, ROS1, BRAF, MET, RET, NTRK, and PD-L1, depending on the setting and available therapy.
Age also played a major role. Patients older than 80 years had a 15.4% lower cumulative incidence of treatment at 180 days compared with patients aged 65 to 69 years. This does not necessarily mean that all older patients should be treated the same way, but it does show that advancing age strongly influences treatment decisions in practice.
Tumor histology mattered as well. Patients whose cancer was classified as NSCLC not otherwise specified had a 12.8% lower cumulative incidence of treatment at 180 days than those with adenocarcinoma. Adenocarcinoma is more likely to undergo biomarker testing and may be easier to match with modern targeted treatment strategies, which may help explain part of the difference.
Other factors associated with treatment receipt included comorbidity burden, marital status, Medicare Part C or Part D coverage, rurality, and race and ethnicity. These differences were smaller than the effects of specialist referral and biomarker testing, but they point to real-world gaps in access and care delivery.
Why these findings matter
This study highlights a major tension in cancer care for older adults. On one hand, treatment options for metastatic NSCLC have never been better. On the other hand, many older patients still do not receive systemic therapy at all.
Some patients truly may not be candidates for treatment because of poor functional status, severe illness, or a very limited life expectancy. In those cases, comfort-focused care may be the right choice. But the study suggests that treatment underuse is not explained by medical severity alone. The strong associations with oncology referral and biomarker testing suggest that access to specialist evaluation and modern diagnostic workup may be key steps that determine whether a patient is offered therapy.
This matters because older adults are not a single, uniform group. Many people in their late 70s or 80s can still tolerate treatment if it is tailored carefully. Others may benefit from less intensive regimens, shorter courses, or targeted therapies with better side-effect profiles than older chemotherapy alone. The challenge is to match the right patient to the right treatment rather than assuming age alone should rule therapy out.
The findings also suggest that systems of care play a major role. Patients who are seen by oncology specialists are more likely to get treated, which may reflect faster diagnosis, more complete staging, better access to biomarker testing, and clearer discussion of treatment options. Coverage differences, rural residence, and race or ethnicity may also reflect unequal access to these same steps.
Limitations to keep in mind
As with any observational study, this one can show associations but cannot prove that one factor directly caused another. For example, referral to oncology was linked with higher treatment use, but the study cannot say referral alone caused treatment. It is also possible that patients who were healthier were more likely to be referred in the first place.
The study relied on claims and registry data, which are powerful for measuring large-scale patterns but cannot capture every clinical detail. Information about performance status, patient preferences, family support, or the exact reasons treatment was not given may not be fully available.
Even so, the size of the cohort and the long study period make the findings important. They show a clear real-world pattern: many older adults with metastatic lung cancer are still not receiving systemic therapy, and the biggest differences appear to be tied to specialist involvement and biomarker testing.
Bottom line
Among more than 250,000 older adults with metastatic non-small cell lung cancer, fewer than half ever received systemic treatment, and treatment rates improved only slightly from 2006 to 2021. Referral to an oncology specialist and biomarker testing were strongly associated with treatment receipt, while advanced age and nonspecific tumor histology were linked to lower treatment use.
The study suggests that improving access to specialist care, timely biomarker testing, and individualized treatment discussions could help more older adults benefit from modern lung cancer therapy.