When you have small cell lung cancer (SCLC), your cancer care team may talk with you about the risk of cancer spreading to your brain. For many years, doctors have used a treatment called prophylactic cranial irradiation (PCI) to lower that risk.
PCI is radiation given to the brain even when scans don’t show cancer there. The idea is to treat cancer cells that may be present but are too small to see.
Now, new research suggests that some people with SCLC may be able to skip this preventive brain radiation and instead have regular brain MRI scans to watch closely for signs of cancer.
The findings come from the phase III SWOG S1827 MAVERICK trial, presented at the 2026 World Conference on Lung Cancer (WCLC). The study found that people who had regular MRI scans without PCI had better cognitive failure-free survival and fewer serious treatment-related side effects than people who had both MRI scans and PCI.
For patients, this could represent an important change: instead of treating the brain before cancer is found, doctors may be able to monitor the brain closely and treat cancer if it appears.
Why is the brain an important concern in SCLC?
SCLC can spread to the brain. Because of this risk, doctors have historically used PCI after initial treatment to try to prevent brain metastases from developing.
PCI also exposes the brain to radiation. Radiation to the brain can cause side effects, including problems with memory and other thinking abilities.
MAVERICK was designed to help answer how doctors can reduce the risk of brain metastases without giving patients treatment they may not need.
What did the MAVERICK trial compare?
The study included 304 people with either limited-stage or extensive-stage SCLC. Everyone had finished their initial treatment and had an MRI showing no cancer in the brain.
Patients were randomly assigned to one of two groups.
One group had regular brain MRI scans but did not receive PCI. The other group had regular MRI scans plus PCI.
Both groups were closely monitored. Patients had brain MRIs every three months during the first year and every six months during the second year.
The researchers also checked patients’ cognitive function at the same intervals. These tests looked at abilities such as memory, verbal skills, and how quickly a person could complete certain mental tasks.
Patients who skipped PCI had better cognitive outcomes
The results were encouraging.
After a median follow-up of 22 months among patients who were still living, those who received MRI surveillance alone had a 40% lower risk of cognitive failure or death compared with those who received MRI surveillance plus PCI.
Cognitive failure-free survival measures how long people remain alive without experiencing a significant decline in thinking or memory abilities. The finding doesn’t simply mean that MRI surveillance helped people live longer. It means that patients who avoided PCI were more likely to remain alive without a significant decline in cognitive function during the study period.
This is particularly meaningful for patients because treatment is about more than controlling cancer. Being able to remember things, think clearly, communicate, and maintain independence can have a major impact on everyday life and quality of life.
The cognitive benefit was seen in people with both limited-stage and extensive-stage SCLC. It was also similar regardless of whether patients received immunotherapy.
Did avoiding PCI mean more cancer spread to the brain?
The study found that brain metastasis-free survival was not significantly different between the two groups.
In other words, researchers didn’t find a statistically significant difference in the length of time patients remained free of cancer in the brain between those who received MRI surveillance alone and those who received MRI surveillance plus PCI.
That’s important because the MRI approach depends on finding brain metastases early through regular monitoring rather than trying to prevent every possible brain metastasis with radiation.
If a future MRI does show cancer in the brain, the care team can then discuss treatment options based on where the cancer is, how much is present, and the patient’s overall situation.
MRI surveillance also caused fewer serious side effects
There was another important difference between the groups: serious treatment-related side effects were less common among people who had MRI surveillance alone.
Severe treatment-related side effects occurred in 0.8% of people who had MRI surveillance alone compared with 7.9% of those who also received PCI. Avoiding PCI therefore has the potential to reduce some of the risks that come with treating the brain with radiation.
What about survival?
The researchers also looked at overall survival, but those results are not final yet. In an early analysis, there was no apparent difference in overall survival between the two groups. The researchers plan to conduct a final analysis.
Why is this research important for people with SCLC?
The way doctors treat SCLC has changed as technology has improved.
These findings may change how doctors approach brain monitoring after initial treatment for SCLC, but your treatment plan should be based on your individual situation.
If your doctor has recommended PCI, ask whether regular MRI surveillance without PCI could be an option for you. You may also want to ask:
- How often will I need brain MRIs?
- What are the potential benefits and side effects of PCI in my situation?
- Would MRI surveillance alone be appropriate for me?
- What would happen if an MRI shows cancer in my brain?
- How could PCI affect my memory or thinking?
- How would you monitor my cognitive function over time?
The MAVERICK trial is an important step toward more individualized treatment for SCLC. Rather than automatically treating the brain when no cancer can be seen, regular MRI surveillance may allow doctors to closely monitor patients while avoiding the potential effects of preventive brain radiation.
Disclaimer: The information provided in this article is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Outcomes4Me is not acting as your caregiver, and any suggestions or guidance offered should not replace the advice of your healthcare provider or qualified medical professional. Always seek the guidance of your physician or other qualified health provider with any questions you may have regarding a medical condition.
