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What Is Adenocarcinoma?

July 25, 2025

You may not recognize the word “adenocarcinoma,” but it’s actually one of the most common types of cancer.

It can show up in different organs in the body — including the lungs, colon, breast, prostate and more — which means it’s important to understand what it is and how it’s diagnosed.

We asked Srinivas Mandavilli, MD, chief of pathology and laboratory medicine at Hartford Hospital, to explain what it is and when to talk to your doctor.

What is adenocarcinoma?

Adenocarcinoma is a type of cancer that starts in epithelial cells — the cells that line many organs and surfaces in the body.

What sets adenocarcinoma apart is that the cancer cells can produce substances like mucus or digestive fluids.

“This gland-like behavior is why adenocarcinoma often develops in organs where these secretions are normally made,” says Dr. Mandavilli.

Epithelial cells are found in many organs, including:

• Breast
• Colon and rectum
• Gallbladder
• Kidney
• Lung
• Ovaries
• Pancreas
• Prostate
• Stomach

> Related: 5 Early Signs of Colon Cancer You Should Know

Is adenocarcinoma always cancerous?

Yes – adenocarcinoma is considered malignant, which means it can grow and may spread if left untreated.

“That said, not all adenocarcinomas behave the same,” says Dr. Mandavilli. “Their aggressiveness can depend on where they form, how big they are and what they look like under the microscope. We look at all these factors to help guide treatment.”

> Related: 4 Types of Cancer That May Be Hereditary 

What are the symptoms of adenocarcinoma?

It depends on where the cancer starts – and for some people, there may be no symptoms early on.

“Adenocarcinoma in the colon may cause blood in the stool,” says Dr. Mandavilli. “But in the lungs, it might show up as a lingering cough or trouble breathing.”

Because this cancer can start in many different organs, symptoms often vary based on where it begins. That’s why there’s no one-size-fits-all list.

But here are a few possible signs to watch for:

• Changes in bowel habits lasting more than a few days.
• Extreme fatigue that doesn’t improve with rest.
• Ongoing shortness of breath.
• Unexplained weight loss.

If a physical exam is the next step, your doctor may also recommend imaging such as a CT scan, or lab tests to gather more information. Sometimes, a biopsy may confirm the diagnosis and help guide your treatment plan.

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Should you talk to your doctor?

It’s always a good idea to mention any new or unexplained symptoms during a check-up, even if they seem minor.

“Adenocarcinomas, like most cancers, are most treatable when we catch them early,” says Dr. Mandavilli. “Starting the conversation gives us a chance to look at your overall risk – and take proactive steps if we need to.”