What happens when your doctor suspects lung cancer

If your doctor thinks you might have lung cancer, they will order imaging tests to look at your lungs, then take a tissue sample to confirm the diagnosis. The process usually starts with a chest X-ray or CT scan, moves to a biopsy (removing a small piece of lung tissue to examine under a microscope), and includes blood tests and sometimes additional scans to see if cancer has spread. Most people go through these steps over a few weeks before receiving a final diagnosis.

The path from "something looks odd on the scan" to "you have lung cancer" involves multiple doctors and tests because each step answers a different question: Is there a growth? Is it cancer? What type? How far has it spread? You will likely see a primary care doctor, a radiologist (who reads imaging), and a pulmonologist or oncologist (a lung or cancer specialist) before everything is clear.

Key Takeaways

  • Chest X-rays and CT scans are the first imaging tests used to spot abnormal areas in the lungs.
  • A biopsy—taking a tissue sample through a needle, scope, or surgery—is the only way to confirm lung cancer and identify its type.
  • PET scans and brain MRIs help doctors determine whether cancer has spread beyond the lungs.
  • Blood tests and genetic testing of the tumor tissue guide treatment decisions and predict how the cancer may respond to specific drugs.

Imaging tests that show what is in your lungs

A chest X-ray is usually the first test. It is quick, uses a small amount of radiation, and can show large masses or nodules (small rounded growths). If the X-ray shows something suspicious or if you have symptoms but the X-ray looks normal, your doctor will order a CT scan (computed tomography), which takes detailed cross-section images of your chest and is much better at finding small nodules.

A CT scan takes about 10 to 30 minutes and involves lying still on a table that slides through a ring-shaped machine. You may receive an injection of contrast dye to make blood vessels and certain tissues show up more clearly. The scan produces hundreds of images that a radiologist reviews to measure any nodules, describe their shape and edges, and note whether they look more or less suspicious for cancer.

If a nodule is very small (less than 8 millimeters across), your doctor may recommend watching it with follow-up CT scans every few months rather than biopsying it right away, because most tiny nodules are not cancer. If a nodule is larger or has features that concern your doctor, the next step is a biopsy.

Biopsy: taking tissue to confirm cancer

A biopsy is the only way to know for certain whether an abnormal area is cancer. Your doctor removes a small sample of tissue and sends it to a pathologist, who examines it under a microscope to look for cancer cells. There are several ways to obtain the sample, and your doctor will choose based on where the nodule is located and how easy it is to reach.

Bronchoscopy is used when the nodule is in the central airways. Your doctor passes a thin, flexible tube with a camera (the bronchoscope) down your windpipe while you are sedated. They can see the nodule directly and use small tools to brush cells or take a pinch of tissue. The procedure takes 30 to 60 minutes, and you go home the same day once the sedation wears off.

CT-guided needle biopsy works for nodules in the outer parts of the lung. You lie on the CT scanner table, and the radiologist uses the CT images to guide a thin needle through your chest wall into the nodule. They withdraw a small core of tissue, then remove the needle. This takes 20 to 40 minutes. You may have some chest discomfort and a small risk of a collapsed lung, but serious complications are uncommon.

Endobronchial ultrasound (EBUS) combines a bronchoscope with ultrasound to reach nodules near the center of the chest. Mediastinoscopy is a surgical procedure in which the surgeon makes a small cut above the breastbone and uses a scope to see and sample lymph nodes in the center of the chest. These are used when nodules are in locations that standard bronchoscopy or needle biopsy cannot easily reach.

In rare cases, if the nodule is deep inside the lung and other methods have not worked, your doctor may recommend a surgical biopsy (thoracoscopy or thoracotomy), in which a surgeon removes the nodule or a larger piece of lung tissue. This is done under general anesthesia in an operating room.

Pathology: what the tissue sample reveals

Once the pathologist examines the biopsy tissue under the microscope, they write a report describing whether cancer is present, what type it is, and certain features that affect treatment. The two main types of lung cancer are non-small cell lung cancer (about 85% of cases) and small cell lung cancer (about 15%). Non-small cell lung cancer is further divided into adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.

The pathologist also looks for specific genetic mutations or protein markers in the cancer cells. Common ones include EGFR mutations, ALK rearrangements, PD-L1 expression, and KRAS mutations. These findings matter because certain drugs target specific mutations—for example, if your cancer has an EGFR mutation, you may benefit from a targeted drug that works specifically on that mutation. Your doctor will discuss these results with you and explain what they mean for your treatment options.

Staging scans: checking if cancer has spread

Once lung cancer is confirmed, your doctor orders additional imaging to determine the stage—how far the cancer has spread. This involves a PET scan (positron emission tomography), which uses a radioactive tracer to highlight areas where cancer cells are active. You receive an injection of the tracer, wait about an hour for it to circulate, then lie in the PET scanner for 20 to 40 minutes. The scan shows whether cancer is present in lymph nodes, bones, the liver, or other organs.

A brain MRI (magnetic resonance imaging) is often done because lung cancer commonly spreads to the brain. MRI uses magnetic fields and radio waves to create detailed images and does not use radiation. The scan takes 30 to 60 minutes, and you lie inside a tube-shaped machine. If you are claustrophobic, tell your doctor—they can give you sedation or use an open MRI machine.

Your doctor may also order a bone scan or additional CT images of the abdomen to check for spread to bones or the liver. The combination of these scans tells your doctor the stage of your cancer (stage 1 through 4) and helps determine whether surgery, chemotherapy, radiation, immunotherapy, or a combination of treatments is most likely to help.

Blood tests and tumor markers

Blood tests do not diagnose lung cancer, but they provide useful information. Your doctor will check your blood counts (to see if anemia or infection is present), kidney and liver function (important before starting chemotherapy), and sometimes tumor markers—proteins that cancer cells release into the bloodstream. Common lung cancer markers include CEA (carcinoembryonic antigen) and NSE (neuron-specific enolase).

Tumor markers can be elevated in people without cancer and normal in people with cancer, so they are not used alone to diagnose the disease. However, if your marker is high at diagnosis, your doctor may track it during treatment to see whether it is falling (a sign treatment is working) or rising (a sign the cancer is progressing).

Timeline and what to expect

The time from first imaging to final diagnosis varies. If you have a clear nodule on CT and go straight to biopsy, you might have a diagnosis within one to two weeks. If the nodule is small and your doctor recommends watching it, you may have follow-up scans every three months for a year or more before a biopsy is done. Once a biopsy is taken, pathology results usually come back within one to two weeks, and staging scans are typically completed within another week or two.

During this waiting period, it is normal to feel anxious. Ask your doctor for a timeline specific to your situation and what each test is looking for. Having a family member or friend attend appointments to take notes can help you remember information and feel less alone.

Frequently Asked Questions

Can a CT scan alone tell me if I have lung cancer?

No. A CT scan can show that something abnormal is present, but only a biopsy—examining tissue under a microscope—can confirm whether it is cancer. A radiologist can describe features that make cancer more or less likely, but the diagnosis requires tissue.

What does it mean if my biopsy is inconclusive?

Sometimes the tissue sample does not contain enough cells or the cells are not clear enough to make a diagnosis. Your doctor may recommend a repeat biopsy, a different biopsy method, or close monitoring with follow-up scans. Inconclusive results are frustrating but not uncommon, especially with small nodules.

Will I need all these tests, or just some of them?

Your doctor will order tests based on your specific situation—where the nodule is, how large it is, your symptoms, and your medical history. Not everyone needs a brain MRI or PET scan; some people need only a chest CT and biopsy. Your doctor will explain which tests you need and why.

Is a biopsy safe?

Biopsies are generally safe, but all procedures carry some risk. Needle biopsies have a small risk of bleeding or collapsed lung. Bronchoscopy can cause sore throat or temporary hoarseness. Serious complications are uncommon. Your doctor will discuss the specific risks of your biopsy method before the procedure.

How long does it take to get all my results?

Pathology results usually take one to two weeks. Staging scans may take another week or two to complete and interpret. In total, from first imaging to a complete diagnosis with staging typically takes three to six weeks, though this varies based on how quickly tests can be scheduled and how complex your case is.