How Is Lung Cancer Diagnosed?
If you are wondering how lung cancer is detected, your doctor has many options for getting a diagnosis. Lung cancer tests include imaging scans, tests of mucus from your lungs, and a biopsy. These tests help your doctor confirm a lung cancer diagnosis or find out whether another condition is causing your symptoms.
Common symptoms that could lead to a lung cancer diagnosis
Your doctor may suspect lung cancer if a physical exam reveals:
- Swollen lymph nodes above your collarbone
- Cough
- Shortness of breath or weak breathing
- Abnormal sounds in your lungs
- Pain in your chest or rib
- Swollen fingertips
- Unequal pupils
- Droopy eyelids
- Weakness
- Shoulder pain
- Swelling of your face, arms, or hands
Can a blood test detect lung cancer?
A blood test called a liquid biopsy can't confirm a lung cancer diagnosis, but it can give your doctor important information about your cancer. "It can help identify the tumor's molecular [genetic] characteristics, guide treatment decisions, and, in some cases, detect early recurrence after treatment," says Hirva Mamdani, MD, medical oncologist and leader of the thoracic oncology multidisciplinary team at the Barbara Ann Karmanos Cancer Institute in Detroit.
A liquid biopsy looks for DNA mutations such as EGFR, ALK, and KRAS in cancer cells circulating in your blood. Certain treatments target those mutations.
Some late-stage lung cancers cause abnormally high blood levels of calcium. If your calcium level is higher than normal without any clear cause, your doctor might suspect lung cancer.
Sputum cytology
Another tool in lung cancer diagnosis, this test checks for cancer cells in a sample of sputum — mucus that you cough up from your lungs. A positive test can confirm a lung cancer diagnosis.
"However, a negative result does not rule out cancer," says Min Kim, MD, a thoracic surgeon at Houston Methodist. Because sputum cytology isn't very accurate, this test is rarely used today, except in cases where people have tumors in their central airways and aren't good candidates for biopsy.
CT scans vs. X-rays for lung cancer diagnosis
Once lung cancer begins to cause symptoms, it is usually visible on an X-ray. Occasionally, lung cancer that has not yet begun to cause symptoms is spotted on a chest X-ray taken for another reason. Your doctor might order a CT scan of your chest for a more detailed exam.
MRI scans use radio waves and strong magnets to take detailed pictures of the inside of your body. An MRI can show if lung cancer has spread to organs such as the brain, spinal cord, or liver.
PET scans inject a mildly radioactive type of sugar into the blood. The sugar collects in cancer cells, which use sugar for energy. A PET scan is another way for your doctor to see where lung cancer has spread. Sometimes, doctors do a combined PET/CT scan.
Lung biopsy
Doctors usually confirm the diagnosis of lung cancer with a lung biopsy. In this procedure, the doctor removes cells or tissue from your lung to examine under a microscope for cancer. A biopsy can be done in a few ways:
Needle biopsy. The doctor guides a needle through your numbed chest wall and removes a sample of fluid or cells. They may use a CT scan to guide the needle to the right place.
Transbronchial biopsy. The doctor guides a thin, lighted tube through your nose or mouth into the air passages to reach the tumor and removes a tiny tissue sample. This procedure is called bronchoscopy.
Thoracoscopic biopsy. While you are asleep and pain-free, the doctor places a scope called an endoscope through a few small cuts in your chest wall and removes a tissue sample. Another name for this procedure is video-assisted thoracic surgery (VATS) biopsy.
Open biopsy. This procedure is done while you are asleep. Your doctor makes a larger cut in your chest and removes a piece of lung tissue. Because this is open surgery, you will need to stay in the hospital afterward.
Thoracentesis. This test helps diagnose lung cancer and ease symptoms such as shortness of breath. The doctor uses a needle to remove fluid from the area between the lining of your chest wall and lungs. If the fluid tests negative for cancer cells, then your doctor may do VATS to examine the lining of your lung for tumors and perform a biopsy.
Advanced lung cancer tests and diagnosis
Lung cancer can spread to other parts of the body, such as the bones, liver, adrenal glands, or brain. If the biopsy confirms lung cancer, your doctor will use other tests to identify the type of cancer and where it's spread.
Nearby lymph nodes can be tested for cancer cells with a procedure called a mediastinoscopy. The doctor uses a long, flexible tube called a mediastinoscope, which is placed into the mediastinum — the space between your lungs and behind your breastbone in the middle of your chest. Imaging techniques such as CT, PET, bone scans, and MRI or CT scans of the brain can detect cancer elsewhere in the body.
Lung cancer screening
People who are at low risk for lung cancer don't need regular screenings, but those at high risk due to their smoking history should get regular tests.
The U.S. Preventive Services Task Force (USPSTF) recommends yearly low-dose CT screening for smokers and former smokers aged 50 to 80 who have smoked for 20 pack years or more and either continue to smoke or have quit within the past 15 years. A pack year is the number of cigarette packs you smoked each day multiplied by the number of years you have smoked. For example, 20 pack years is equal to one pack a day for 20 years, or two packs a day for 10 years. If you quit smoking more than 15 years ago, you may not need to continue screening.
Lung Cancer Treatments
Lung cancer treatment options include surgery, radiation, chemotherapy, immunotherapy, and targeted therapy. Your medical team will recommend one or more of these treatments for you based on your type and stage of lung cancer, as well as your overall health.
Surgery for lung cancer
Surgery to remove part or all of the lung is the preferred treatment for early-stage non-small-cell lung cancer, and it may cure the cancer. Doctors rarely treat small-cell lung cancer with surgery because the cancer has often already spread by the time it is diagnosed.
The surgeon removes the tumor along with surrounding lung tissue and lymph nodes. They may remove part or all of the lobe containing the tumor, or the entire lung. After surgery, you'll stay in the hospital for several days.
Cancer that has spread to lymph nodes between the lungs was once considered inoperable, but combining surgery with chemotherapy has improved survival rates.
Many people with lung cancer, especially smokers, have other lung or heart problems that make surgery difficult. If surgery isn't an option, your doctor will recommend one or more of the other lung cancer treatment options.
Lung cancer radiation
This treatment uses high-energy rays to kill cancer cells. You may get radiation before surgery to shrink the tumor and make it easier to remove, or after surgery to kill any cancer cells that were left behind. You may have to wait to get radiation until after the surgical wound has healed.
Radiation is also a treatment for cancer that can't be removed surgically or for relieving symptoms of late-stage cancers. It's sometimes given together with chemotherapy, which is called chemoradiation.
Chemotherapy for lung cancer
This treatment uses strong medicines that travel through the bloodstream to kill cancer cells all over the body. Because small-cell lung cancer tends to spread widely, it is typically treated with combination chemotherapy (the use of more than one drug), often along with radiation therapy. For early-stage lung cancer, having chemotherapy after surgery may help prevent the cancer from coming back.
Chemotherapy can be a treatment for people whose cancers have metastasized, or spread to distant parts of their body. Since metastatic lung cancer is very difficult to cure, the main goals of treatment are to offer comfort and prolong life. Chemotherapy can shrink tumors, which may lessen pain and other symptoms.
Palliative care is a treatment that's designed to ease pain and other symptoms. You get it alongside your cancer treatment. Palliative care can include surgery, for example, to remove fluid that has collected in the chest.
Stereotactic body radiotherapy (SBRT)
"This is a form of radiotherapy that delivers radiation to a targeted area in a precise way," says Christina Baik, MD, MPH, a physician and associate professor in the clinical research division at Fred Hutch Cancer Center in Seattle. SBRT can deliver high doses of radiation to the cancer without harming nearby tissues.
SBRT treats early-stage lung cancers that are small and haven't spread beyond the lungs. This type of therapy may also be used to treat early-stage tumors that come back.
Radiofrequency ablation (RFA)
RFA creates heat using high-energy radio waves to kill cancer cells. It's delivered with a needle electrode, which the doctor inserts into the tumor using CT or MRI scan to guide it to the right place. RFA is not often used to treat lung cancer today. "SBRT is generally preferred due to its lower complication rate and better local tumor control," Kim says.
Targeted therapy for lung cancer
This group of medicines works by targeting proteins, blood vessels, or other factors that help lung cancer grow. Targeted therapy is mainly a treatment for late-stage cancers, sometimes combined with chemotherapy or other medicines.
Epidermal growth factor receptor inhibitors block EGFR — a protein on the surface of the cancer cells that helps them grow faster. Examples are:
- Afatinib (Gilotrif)
- Amivantamab (Rybrevant)
- Dacomitinib (Vizimpro)
- Erlotinib (Tarceva)
- Gefitinib (Iressa)
- Lazertinib (Lazcluze)
- Osimertinib (Tagrisso)
Angiogenesis inhibitors, such as bevacizumab (Avastin) and ramucirumab (Cyramza), stop the growth of new blood vessels that supply the tumor. These medicines help control advanced lung cancer.
ALK inhibitors work on the estimated 5% of non-small-cell lung cancers that have a change in a gene called ALK. The faulty gene produces the ALK protein, which makes cancer cells grow and spread more easily.
Medicines that target the ALK protein include:
- Alectinib (Alecensa)
- Brigatinib (Alunbrig)
- Ceritinib (Zykadia)
- Crizotinib (Xalkori)
- Ensartinib (Ensacove)
- Lorlatinib (Lorbrena)
ROS1 inhibitors and ROS1 tyrosine kinase inhibitors (TKIs) shrink tumors in people whose cancer carries the ROS1 gene change. These drugs include:
- Crizotinib (Xalkori)
- Entrectinib (Rozlytrek)
- Lorlatinib (Lorbrena)
- Repotrectinib (Augtyro)
KRAS inhibitors, such as adagrasib (Krazati) and sotorasib (Lumakras), treat people whose cancer has changes in the KRAS gene.
BRAF inhibitors work on cancers that have changes in the BRAF gene. They include:
- Dabrafenib (Tafinlar)
- Encorafenib (Braftovi)
- Vemurafenib (Zelboraf)
RET inhibitors work on a small percentage of non-small cell lung cancers with a mutation in the RET gene. Examples of RET inhibitors are:
- Cabozantinib (Cometriq, Cabometyx)
- Pralsetinib (Gayreto)
- Selpercatinib (Retevmo)
MET inhibitors treat metastatic non-small-cell lung cancers with changes to the MET gene. They include:
- Capmatinib (Tabrecta)
- Crizotinib (Xalkori)
- Tepotinib (Tepmetko)
HER2-directed drugs work against non-small-cell lung cancers with HER2 gene changes. Fam-trastuzumab deruxtecan-nxki (Enhertu) and ado-trastuzumab emtansine (Kadcyla) are antibody-drug conjugates. The antibody finds and attaches to the HER2 protein on the cancer cells, and then delivers chemo directly to it.
Zenocutuzumab-zbco (Bizengri) is a type of drug called a bispecific antibody. It latches onto HER2 and another protein called HER3 on the cancer cells, then attacks those cells.
TRK inhibitors, such as entrectinib (Rozlytrek) and larotrectinib (Vitrakyi), treat lung cancers that have changes in one of the NTRK genes.
It's now common for people to be tested for these and other genetic changes to determine if a targeted drug can effectively fight their type of lung cancer.
Immunotherapy for lung cancer
This treatment helps your immune system fight the cancer. The most commonly used immunotherapy drugs for lung cancer are called checkpoint inhibitors.
Normally, immune cells called T-cells recognize and attack cancer cells. Lung cancer cells sometimes make proteins that help them "hide" from T-cells. Checkpoint inhibitors essentially reactivate the immune system, freeing it to attack the cancer.
"Used alone or in combination with chemotherapy, these therapies have achieved long-term survival outcomes once thought impossible in lung cancer," Mamdani says. "However, they are not effective for everyone."
Examples of checkpoint inhibitors are:
- Atezolizumab (Tecentriq)
- Cemiplimab (Libtayo)
- Durvalumab (Imfinzi)
- Ipilimumab (Yervoy)
- Nivolumab (Opdivo)
- Pembrolizumab (Keytruda)
- Tremelimumab (Imjudo)
Takeaways
Doctors use a combination of imaging tests, blood tests, and biopsy results to diagnose lung cancer. Your choice of treatment depends on the type and stage of cancer you have, as well as your health. Surgery, radiation, chemotherapy, immunotherapy, and targeted therapy are just some of the treatments for lung cancer.
Lung Cancer Diagnosis FAQs
How long can you have lung cancer before symptoms develop?
Lung cancer often doesn't cause symptoms until it has reached a late stage. You can have this cancer for years before any symptoms appear.
What is the life expectancy of someone with lung cancer?
When the cancer is caught at an early stage and treated, 65% of people live for at least five years. The average five-year survival rate for all lung cancer stages is 28%.
Can lung cancer be detected early?
Screening with low-dose CT scans can pick up lung cancer early, when it's most treatable. Guidelines recommend this test for people aged 50 to 80 with a 20 pack-year smoking history who currently smoke or quit within the last 15 years.
Can lung cancer be cured?
Some lung cancers are curable if they're caught early and treated before they spread.
