Lung adenocarcinoma is the most common type of lung cancer diagnosed in the U.S. Just over half of all non-small-cell lung cancers (NSCLCs) are adenocarcinomas.
Finding out that you're at risk of lung cancer, or have an adenocarcinoma, can be a challenge. But learning more about the condition, lung cancer symptoms, and adenocarcinoma treatments can help you better prepare.
What Is Lung Adenocarcinoma?
Adenocarcinomas grow from glandular cells lining your airways and lungs. These cells make mucus to keep your lungs moist.
"Lung adenocarcinomas usually start in glandular cells that are on the periphery, (outer parts) of your lungs," says David Sidransky, MD, a lung cancer specialist at the Johns Hopkins School of Medicine in Baltimore.
What's the risk of lung adenocarcinoma?
Most lung cancers found in nonsmokers are adenocarcinomas, but this type of NSCLC is common in smokers, too. You have a higher risk of lung adenocarcinoma if you:
- Smoke or breathe in secondhand smoke
- Are exposed to radon gas
- Are sensitive to air pollution
- Are exposed to work chemicals
- Have a family history of lung cancer
Why lung adenocarcinomas are common
Rates of lung adenocarcinoma are on the rise. "We think it's due to the increase in filtered cigarettes and air contaminants, both of which cause smaller particles to reach the outer parts of the lungs," says Sidransky.
Newer low-tar filters in cigarettes (for smokers) may cause deeper inhales, and higher levels of air pollution can lead to difficulty breathing. To fill your lungs with air, bigger inhales may also pull harmful particles deeper into your lungs, raising your risk of lung cancer.
What Are Lung Adenocarcinoma Symptoms?
Lung adenocarcinoma often doesn't have symptoms, especially in the early stages. But knowing if you’re at higher risk of lung adenocarcinoma can help you spot and treat it early. A low-dose computed tomography (CT) scan is the only suggested test that can screen for lung cancer.
You’ll get scanned every year if you:
- Are between 50 and 80, and
- Have a 20-pack year history, meaning you smoked one pack a day for 20 years or an equal amount, and
- Continue to smoke or have quit within the last 15 years
This test helps your doctor see if there are changes inside your lungs. But you’ll need more tests to confirm lung adenocarcinoma. Your doctor will do an exam and ask you about symptoms, like pain.
Early lung cancer signs
Lung pain is often an earlier symptom. "Your lungs have nerve endings, so when tumors initially grow, they can press on the lung surface and cause pain," says Nabil Rizk, MD, a lung cancer specialist and chief of thoracic surgery at Hackensack University Medical Center in New Jersey.
Sometimes your lung cancer can grow without signs, until the tumor presses on other organs or structures. At first, you may notice symptoms like:
- Upper back and chest pain (worse when you laugh, cough, or breathe)
- Fatigue
- Shortness of breath
- Wheezing
- Chronic cough that doesn’t go away
- Coughing up blood
- Voice changes (hoarse)
Advanced lung cancer signs
If the adenocarcinoma grows larger, you can get changes in your symptoms, especially if it spreads. "In later stages, the adenocarcinoma can spread to the lining of the chest cavity, which can cause fluid to build up and lead to shortness of breath," says Rizk.
Later-stage lung cancer symptoms can include:
- Serious pain
- Problems swallowing (dysphagia)
- Other upper respiratory complications
If your lung cancer spreads, your symptoms depend on where the adenocarcinoma grows in your body.
How Is Lung Adenocarcinoma Diagnosed?
The journey to diagnose lung cancer starts with gathering clues about the spot on your lung. Your doctor uses the most gentle tests first, working up to a biopsy and, if needed, surgery.
Your doctor can use a biopsy to diagnose your lung adenocarcinoma. But sometimes, your doctor may suggest surgery instead. This means your doctor removes the tumor and gives you a diagnosis at the same time.
Imaging scans for lung cancer
Your doctor may order imaging tests to find your tumor, see nearby structures, or stage your cancer. Lung cancer often grows without symptoms, so your doctor may first suspect adenocarcinoma on a scan, such as:
- Chest X-ray
- Computed tomography (CT) scan
- Magnetic resonance imaging (MRI) scan
- Positron emission tomography (PET) scan
- Bone scan
Some tests, like the low-dose CT scan, hint at lung cancer. And others, like biopsy and surgery, can diagnose it.
Biopsy for lung adenocarcinoma
To diagnose your lung cancer type and stage, your doctor will do a biopsy – look at a small piece of your lung tissue under a microscope. Your doctor may do the biopsy using:
- Bronchoscopy, a flexible tube with a camera inserted through your mouth or nose and down your windpipe
- Endobronchial ultrasound bronchoscopy (EBUS), which uses ultrasound to guide the bronchoscopy and check out nearby lymph nodes
- Needle aspiration, in which a needle goes through the skin, directly into your adenocarcinoma
- CT scan, which can pinpoint the tumor and guide a thin needle into it
- Thoracentesis, which uses a needle and small catheter to take a bit of fluid from around your lungs
- Mediastinoscopy or mediastinotomy, in which a needle takes a small piece of tissue from the area between your lungs called the mediastinum
You'll review your testing with your doctor after the pathology report is ready.
Pathology Report for Lung Adenocarcinoma
Your pathology report can tell you about lung adenocarcinoma and the stage. There are three types of lung adenocarcinomas, based on how they spread and look:
Adenocarcinoma in situ. The cells are abnormal, not cancer, but still found in your glandular lung tissue, and they haven't spread anywhere else. "It often looks like ground glass on a CT scan," says Rizk.
Minimally invasive adenocarcinoma. Your tumor is very small – less than 3 centimeters (cm) – but has started to spread into nearby tissues. It also looks like ground glass, but the center of the lobes have some partly solid areas that are less than 5 millimeters (mm) on the CT scan.
Invasive adenocarcinoma. The cancer cells have spread to surrounding tissues and nearby lymph nodes.
Grouping adenocarcinoma cells together
Looking at lung adenocarcinoma cells under a microscope, your doctor can group the ones that look alike together. The five main types are based on the way adenocarcinoma cells grow.
These different growth patterns, called histological subtypes, may also predict how fast or far your cancer grows (prognosis).
Lepidic-predominant. The cells grow in a single layer along the surface of your lung without invading nearby tissues – less aggressive than other lung adenocarcinomas.
Acinar-predominant. This very rare adenocarcinoma forms thin columns of cells that look like tubes.
Papillary-predominant. A rare, very aggressive adenocarcinoma, it looks cone-shaped (papillary) and tends to have a worse prognosis.
Micropapillary-predominant. It's similar to papillary-predominant adenocarcinoma, but its cone-shaped cells are smaller.
Solid-predominant with mucin production. These adenocarcinomas are made up of solid sheets of tumor cells with mucus (mucin) inside.
"The different subtypes tend to have different prognoses, but they don't generally impact how we treat these cancers," says Rizk. "We tend now to focus more on the genetic and molecular makeup of the tumor, rather than the histological subtype."
Lung adenocarcinoma biomarker testing
Biomarker testing, also called molecular testing, guides your doctor in choosing the best treatment. The tests check for DNA changes in your tumor cells that some treatments can target. These DNA changes inside lung cells, called driver mutations, can allow cancer cells to grow and spread.
When you get your biopsy done, ask your doctor to take enough tissue for biomarker testing, too. "This looks for abnormalities in your tumor's DNA, which tend to be more common with adenocarcinoma," says David Tom Cooke, MD, national spokesperson for the American Lung Association.
"[The testing] can help us guide treatment, including groundbreaking, new targeted therapies and immunotherapies," says Cooke, who also serves as the chief of the Division of General Thoracic Surgery at the University of California Davis School of Medicine in Sacramento.
Some mutations common in lung adenocarcinoma cancer cells include:
- ALK, 5% of NSCLCs, often adenocarcinoma
- EGFR, 10% to 20% of NSCLCs, found more in nonsmokers
- KRAS, up to a quarter of NSCLCs, many of which are adenocarcinomas
Your doctor also checks for PD-L1, a protein that helps predict how well immunotherapy might work. After your doctor knows about the driver mutations causing the adenocarcinoma to grow, they can choose the best treatment. Next, they'll stage your adenocarcinoma and begin treatment.
Staging Lung Adenocarcinoma
Your doctor uses the biopsy and imaging to stage your lung adenocarcinoma – find out how far the cancer has spread. Your doctor may use the TNM staging system to stage your tumor, which stands for:
- T, size and extent of the main tumor
- N, how far it's spread to nearby lymph nodes
- M, metastasis (its spread) outside of the lungs to places like the brain, bones, or pleural fluid (fluid around your lungs)
Next, your doctor may stage your cancer using a five-stage system (Stage 0 to Stage IV).
How is adenocarcinoma staged?
Different tumor stages combine numbers and letters together to tell you the size and far your adenocarcinoma has spread. Staging can be complex, but learning about how it's done can help you prepare.
Here’s an overview of lung adenocarcinoma stages.
Stage 0
This lung adenocarcinoma “in situ” (Tis) only lines the top layer of your lung’s air passages (N0) and hasn't spread to other tissues (M0).
Stage I
These tumors only grow in one lung (M0) and haven’t spread to your lymph nodes (N0).
Stage IA. The minimally invasive adenocarcinoma (T1mi) is smaller than a grape, under 3 centimeters (cm). The tumor is about 1 cm (T1A) across, or 2 cm (T1B), but it hasn’t spread into nearby tissues.
Stage IB. Your tumor is 3 to 4 cm (T2A) across.
Stage IC. Your tumor is up to 3 cm across (T1A, B, or C) but hasn’t spread to nearby tissues.
Stage II
These adenocarcinomas aren't in other parts of your body (M0) and get staged based on tumor size and spread into the chest wall, heart lining, or lymph nodes:
- Not spread to your lymph nodes (N0)
- Spread to the lymph nodes or around your breathing (bronchial) tube on the same side as the tumor (N1)
- Spread to the lymph nodes under your bronchial tube or in the space between your lungs on the same side as the tumor (N2a)
Stage IIA. Your tumor is under 3 cm (T1A, T1B, or T1C) or grows up to 5 cm (T2B) – the size of a lime.
Stage IIB. The adenocarcinoma can be:
- Under 3 cm (T1A, T1B, or T1C)
- Between 3 and 5 cm across (T2A or T2B)
- Between 5 and 7 cm (T3)
Stage III
The cancer isn’t in other parts of your body (M0). The lung cancer is in nearby lymph nodes (N0, N1, or N2a), in the mediastinum (N2b), or in lymph nodes near the other lung (N3).
Stage IIIA. The adenocarcinoma can grow:
- No larger than 3 cm (T1A, T1B, T1C), up to 5 cm (T2), and between 5 and 7 cm (T3)
- Bigger than 7 cm (T4), the size of a peach
Stage IIIB. Your tumor can grow:
- Up to 3 cm across (T1)
- Bigger than 3 cm (T2), or between 5 and 7 cm (T3)
- Larger than 7 cm (T4)
Stage IIIC. Your tumor may be under 7 cm (T3) or bigger than 7 cm (T4), and the lymph nodes between your lungs may have cancer cells (N3).
Stage IV
After lung adenocarcinoma spreads to other parts of your body, the tumor can be any size (any T) and has spread to your lymph nodes (any N).
Stage IVA. The lung cancer has spread outside your chest area:
- M1A, fluid can build up around your heart or lungs
- M1B, grows in another organ like your liver, adrenal glands, or bones
Stage IVB. Your adenocarcinoma has spread outside of your chest to a distant organ (M1C1). Your cancer may also be in many other organs and parts of your body (M1C2).
How Is Lung Adenocarcinoma Treated?
Your treatment can depend on the stage of your adenocarcinoma and the DNA changes in the cancer cells, as detected by biomarker testing. Here are some treatments that your medical team may discuss.
Surgery for adenocarcinoma
Surgery is one of the first treatments you'll get with early-stage lung adenocarcinoma (stage I or II). "If your tumor is large, you may have chemotherapy beforehand to shrink the tumor," says Cooke.
To remove your lung adenocarcinoma, your doctor may suggest:
- Lobectomy to remove one lobe of your lung
- Segmentectomy or wedge resection, if your tumor is under 2 cm, which takes out a small part of your lung
- Pneumonectomy, which removes an entire lung if a lobectomy isn’t an option or your adenocarcinoma is near the middle of your chest and harder to reach
Your lung cancer treatment plan tells you if you'll get other treatments before or after surgery. "Once an adenocarcinoma begins to spread, usually other treatments besides surgery, such as chemotherapy or radiation, are necessary," says Rizk.
Radiation therapy
High doses of X-rays, radiation therapy, can destroy cancer cells. Your doctor may suggest this treatment to shrink tumors not removed with surgery.
"We often use a technique called stereotactic ablative body radiation (SABR), where we give a strong amount of radiation that zaps and kills the tumor," says Cooke. "It's not as effective as surgery, but it is still very powerful, especially if your cancer has not yet spread to your lymph nodes."
Chemotherapy for lung cancer
If your tumor is more than 4 cm across, after your surgery, chemotherapy can help slow or stop cancer cell growth. Chemo is usually given in a 21- or 28-day cycle for about three months.
Your doctor will probably combine two types of chemotherapy medicines. Two commonly used ones are cisplatin (Platinol, Platinol-AQ) and carboplatin (Paraplatin).
Immunotherapy for adenocarcinoma
Immunotherapy medicines can help your body find and kill cancer cells. Many immunotherapies treat NSCLC, including adenocarcinoma, such as PD-1/PD-1L and CTLA-4 inhibitors.
These immune checkpoint inhibitors don't allow your immune system to turn "off," so it continues to kill cancer cells.
Targeted therapy and driver mutations
Targeted treatments can block certain proteins made from DNA changes, also called driver mutations, to kill the cancer cells. Usually reserved for advanced or metastatic lung adenocarcinoma, your doctor may suggest earlier targeted treatment if you have a specific gene mutation that drives cancer growth.
Here are a few common adenocarcinoma driver mutations and some possible treatment examples:
- Epidermal growth factor receptor (EGFR). Osimertinib (Tagrisso) or amivantamab (Rybrevant) plus lazertinib (Lazcluze)
- ALK. Alectinib (Alecensa)
- ROS1. Crizotinib (Xalkori)
Your medicine and treatment schedule (when and how long it's given), depend on the stage of your cancer, says Cooke. Some treatments are better for earlier-stage tumors, while other medicines only work for advanced disease (metastatic lung cancer). The good news is that there are lots of new options to choose from.
Outlook for Lung Adenocarcinoma
How long you live after treatment for lung cancer can depend on the stage, type of adenocarcinoma, driver mutations, and your overall health. Recent research shows that just under 40% of people with adenocarcinoma live for three years.
This number rises to 84% if you’re diagnosed earlier (stage I). In fact, the median overall survival rate has more than doubled in the past 20 years – people are living longer with lung cancer.
5-year survival rates
No one can guess exactly how long you'll live. But these numbers can give you a general idea about how many people live five years with NSCLC, including lung adenocarcinoma:
- 67% if the cancer stays inside the lung (localized)
- 40% if the cancer grows into nearby tissues or lymph nodes (regional)
- 12% if the cancer spreads (metastasizes) to other parts of your body (distant)
Cooke says you can help improve your outlook if you follow your treatment plan and do all your follow-up care. This can help you lower your chances of the cancer coming back.
Your lung cancer treatment team can help you manage any treatment side effects and refer you to a palliative care specialist. This doctor can help relieve pain, stress, and other symptoms – they care about the quality of your life.
"The future has never been brighter for lung adenocarcinoma, thanks to all the advances, especially with targeted therapy and immunotherapy," says Cooke.
Takeaways
The most common form of NSCLC, lung adenocarcinoma, is on the rise. It can show up without symptoms, but a yearly low-dose CT scan can screen for lung tumors if you're at risk. And thanks to immunotherapy and targeted treatments, the overall survival rate has dramatically gone up over the last 20 years. Ask your doctor about biomarker testing to help pair you with the right lung cancer treatment.
Lung Adenocarcinoma FAQs
What is the most common location of lung adenocarcinoma?
Lung adenocarcinoma usually starts on the outer edges of your lung, in the peripheral lung tissue. This type of lung cancer also tends to grow slower than other lung cancers.
How aggressive is adenocarcinoma cancer?
It can depend on the grade of your cancer cells – how much they look like healthy lung cells. “When we take a biopsy, we look at the tumor under a microscope to determine its grade,” says Cooke. “There are four different grades. Grade 1 cells look like normal cells and are very slow growing, while grade 3 and 4 cells look very abnormal and spread very quickly.”
What are the complications of lung adenocarcinoma?
If left untreated, lung adenocarcinoma can cause serious complications such as:
- Chest infections
- Neurological problems
- Syndromes like Horner’s, Pancoast, or superior vena cava (SVC)
- Serious fluid buildup around your lungs or heart (malignant pleural or pericardial effusion)
- Death
But knowing the signs and getting screened early for lung cancer helps you choose the best targeted treatment for your lung adenocarcinoma treatment plan.
