Pope Leo XIV's cancer diagnosis has put a spotlight on the most common form of lung cancer. lung adenocarcinoma, accounting for an estimated 45% of all lung cancer cases globally. It is a subtype of non-small cell lung cancer (NSCLC), which represents nearly 81% of lung cancers.
An estimated 229,000 people in the U.S. will be diagnosed with lung cancer in 2026. While lung cancer remains the leading cause of cancer deaths nationwide, a patient's outlook can vary considerably depending on how early the cancer is found and the biology of the tumor. For people with NSCLC, the five-year relative survival rate is 67% when the cancer is confined to the lung, compared with 12% once it has spread to distant parts of the body. Advances in precision medicine are also changing how physicians treat the disease. Genetic testing can reveal changes driving an individual patient's cancer and, in some cases, point physicians toward treatments designed to target them.
We spoke with Trever Bivona , MD, PhD, UCSF professor of Medicine, about what people should know about lung adenocarcinoma, how physicians determine the best treatment, and why the genetics of a patient's tumor increasingly matters.
What is lung adenocarcinoma, and what does this diagnosis mean?
Lung adenocarcinoma is diagnosed by a pathologist examining tissue obtained from a biopsy or surgery. The diagnosis is only part of what we need to know. Lung adenocarcinomas can have different genetic changes that affect how the cancer behaves and how it may be treated. Identifying those changes can help doctors tailor treatment to a patient's particular tumor.
How treatable is lung adenocarcinoma today, and what determines a patient's outlook?
Lung adenocarcinoma is often more treatable than some other forms of lung cancer, and treatment has advanced significantly. A patient's outlook depends on several factors, including how far the cancer has spread and, increasingly, the tumor's specific molecular characteristics. That's why just knowing that someone has lung adenocarcinoma doesn't tell us the whole story.
Why is the stage of lung cancer so important?
We're seeing some overlap in how early- and later-stage disease are treated as new therapies become available. Stage tells us how much cancer is present and whether it has spread beyond the lung, and it remains very important in determining treatment. Early-stage lung cancer is often treated with surgery, sometimes along with chemotherapy. Later-stage disease is generally treated with medications, including precision targeted therapies and immunotherapy, rather than surgery, with some exceptions where surgery can be helpful. Increasingly, however, some targeted therapies and immunotherapies are being used across different stages of lung cancer.
Can someone who has never smoked still develop lung cancer?
Absolutely. There's a stigma around lung cancer because of its association with smoking. Smoking can cause lung cancer, but it's not the only factor. We see patients with lung cancer who have never smoked or who have a remote history of smoking. Lung cancer is a disease that can occur for reasons beyond tobacco use, often related to genetic mutations that arise and cause the cancer.
Once someone is diagnosed, what tests help physicians decide on the best treatment?
First, physicians need to determine exactly what type of lung cancer a patient has, usually through a biopsy or surgery. Imaging tests such as CT or MRI scans can then help determine where the cancer is and whether it has spread.
Another important step is molecular testing to look for genetic changes and markers of immunotherapy efficacy (or lack thereof) that may be driving the cancer and could help guide treatment. This can be done by testing tissue from the tumor or from a site where the cancer has spread, or through a liquid biopsy, which looks for tumor-related genetic material in the blood. The goal is to identify molecular alterations that can be targeted with specific precision treatments.
Why do clinicians test lung tumors for genetic and other molecular changes, and how can those results affect treatment?
We've learned that many lung cancers are driven by specific genetic changes. Two examples are changes in the genes epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma (KRAS). If we identify one of these changes, it can often give us a specific target for treatment. Markers of immunotherapy are also useful for clinicians in recommending treatment.
These findings can dramatically shape how we approach treatment for each patient. Rather than treating every lung adenocarcinoma diagnosis the same way, we are able to identify different molecular profiles and tailor treatment options based on the biology of an individual patient's tumor.
