Lung cancer is the second most common cancer in the United States, and non-small cell lung cancer (NSCLC) makes up about 85% of cases. When it’s caught early—before it has spread—the main treatment is surgery.
The goal of surgery is to remove the tumor with a margin of healthy tissue around it. For decades, that meant removing an entire lobe of the lung (a lobectomy). The lungs have five lobes, three on the right and two on the left. Removing one is a major operation.
But not all tumors are the same. Many early-stage lung cancers are now found through screening CT scans. These tumors are often very small—less than 2 centimeters (about the size of a grape)—and located on the outer edges of the lung.
For these patients, a less aggressive surgery called a sublobar resection—removing just a wedge or a segment of the lung—has been gaining traction. The question is: Is it just as good?
The Old Way vs. The New Way
For years, the thinking was simple: bigger is better. Remove more tissue, and you remove more risk. A lobectomy was considered the gold standard for any tumor that could be surgically removed.
But here’s the twist: That thinking was based on older studies, many from an era before CT scans were common. Those studies often included larger tumors and didn’t always confirm that the lymph nodes were cancer-free before surgery.
This new trial, CALGB 140503, was different. It focused only on patients with small, peripheral tumors (2 cm or less) and required surgeons to check the lymph nodes during the operation to make sure the cancer hadn’t spread. Only then were patients randomly assigned to have either a lobectomy or a sublobar resection.
The result? Removing less lung tissue was just as effective as removing a whole lobe.
How a Smaller Surgery Can Be Just as Effective
Think of a lung tumor like a weed in a garden. The old approach was to dig up the entire garden bed (the lobe) to make sure you got every root. The new approach is to carefully dig out just the weed and a small circle of soil around it (the wedge or segment), leaving the rest of the garden intact.
The key is that the weed is small and hasn’t spread. If you remove it cleanly, the rest of the garden can thrive.
In the same way, if a lung tumor is small, on the edge of the lung, and the lymph nodes are clear, removing a small wedge of lung can be just as effective as removing the whole lobe. The cancer is gone, and the patient keeps more of their lung function.
A Closer Look at the Study
The CALGB 140503 trial was a large, multi-center study that enrolled 697 patients with early-stage lung cancer. All patients had tumors that were 2 cm or smaller and located on the outer edges of the lung. Crucially, surgeons had to perform an intraoperative assessment of the lymph nodes to confirm there was no spread before assigning the patient to a surgery type.
Patients were then randomly assigned to have either a lobectomy or a sublobar resection (wedge or segmentectomy). They were followed for several years to track survival and cancer recurrence.
The results were clear: Sublobar resection was non-inferior to lobectomy in terms of disease-free survival. In other words, patients who had the smaller surgery did just as well in terms of their cancer coming back.
Overall survival was also comparable between the two groups. And the patterns of cancer recurrence were similar, meaning that removing less lung tissue didn’t lead to more aggressive or widespread cancer returning.
This finding was supported by other major trials, like the Japanese JCOG 0802/WJOG 4607L study, which also found that sublobar resection was a safe and effective option for small, early-stage tumors.
But Here’s the Catch
This doesn’t mean every patient with early-stage lung cancer should have a smaller surgery.
The trial only included patients with very specific tumor characteristics: small (≤2 cm), peripheral (on the outer edge of the lung), and node-negative (no spread to lymph nodes). For larger tumors, or tumors in the center of the lung, a lobectomy may still be the best option.
Also, the type of sublobar resection matters. A segmentectomy (removing a larger segment of the lung) may be better than a wedge resection (removing a small wedge) for some tumors, but more research is needed to know for sure.
What Experts Are Saying
The CALGB 140503 trial has been a game-changer in thoracic surgery. It provides strong evidence that for carefully selected patients, a less aggressive surgery can be just as effective.
Experts agree that this trial, along with others like it, has shifted the standard of care. Sublobar resection is now considered an acceptable—and for some patients, a preferable—option for early-stage lung cancer.
But they also caution that patient selection is key. Not every tumor is suitable for a smaller surgery, and the decision should be made by a multidisciplinary team including surgeons, oncologists, and radiologists.
If you or a loved one has been diagnosed with a small, early-stage lung tumor, it’s worth asking your doctor about sublobar resection. This option may allow you to keep more of your lung function and recover more quickly, with the same survival rates as a larger surgery.
However, this is not a decision to make lightly. Talk to your surgeon about the specific characteristics of your tumor and whether a sublobar resection is appropriate for you.
Like any study, CALGB 140503 has limitations. It only included patients with small, peripheral, node-negative tumors, so the results may not apply to other types of lung cancer. The follow-up period was several years, but longer-term data is still needed to confirm the durability of the results.
Additionally, the study did not include patients with tumors larger than 2 cm, or those with cancer that had spread to the lymph nodes. For these patients, a lobectomy may still be the best option.
The CALGB 140503 trial has already changed clinical practice, and its impact will continue to grow. Future research will focus on refining which patients benefit most from sublobar resection and which type of sublobar resection (wedge vs. segmentectomy) is best.
Researchers are also exploring how new technologies, like robotic surgery and advanced imaging, can make sublobar resection even more precise and effective.
For now, the trial provides a clear message: For many patients with small, early-stage lung cancer, less can be more.