What is Adenocarcinoma?

A Type of Cancer Affecting Glandular Tissues

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Adenocarcinoma is a type of cancer that develops from mucous cells. The National Institutes of Health (NIH) National Cancer Institute defines adenocarcinoma as a type of cancer that forms in glands and glandular tissues.

The glandular tissues are broken down into two types: exocrine (glands that secrete via ducts, such as mammary and prostate glands) and endocrine (glands without ducts that secrete directly into the bloodstream, such as the ovaries or thyroid gland). Adenocarcinoma can affect endocrine glands but more commonly affects organs with exocrine glands. The tumor typically develops within the ducts but can ultimately affect any secretory cell.

Most breast, colon, esophageal, pancreatic, and prostate cancers are adenocarcinomas as well as a large proportion of lung cancers.

An ethnic senior woman battling cancer sits with her daughter on the couch

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Types

Although the term “adenocarcinoma” brings to mind lung cancer for many people, adenocarcinomas can develop in any part of the body where there are glands. 

The most common types of adenocarcinoma are listed below. Here is how common they are compared to other types of carcinoma (some of which are listed here):

  • Breast cancer (around 75%)
  • Colorectal cancer (majority)
  • Esophageal cancer (majority)
  • Lung cancer (around 40%)
  • Pancreatic cancer (around 80%)
  • Prostate cancer (majority)
  • Stomach cancer (majority)

Symptoms

Symptoms can vary by the adenocarcinoma type. Some may present with early symptoms (such as a lump in the breast) or remain largely asymptomatic until the disease is advanced and metastatic. Those with adenocarcinoma may also be asymptomatic. 

  • Adenocarcinoma of the breast: Indications may include a sudden onset of pain, nipple discharge/inversion, new unwavering skin changes, and new notable breast mass.
  • Adenocarcinoma of the colon or rectum: Signs include involuntary weight loss, tiredness, generalized frailty, hematochezia, pain of the abdomen, and obstruction of bowel movements.
  • Adenocarcinoma of the esophagus: Symptoms may include difficulty swallowing, pain in the chest, unexplained weight loss, loss of voice, development of a chronic choice, vomiting, anemia, tiredness, and bone pain.
  • Lung adenocarcinoma: Adenocarcinoma of the lung can present with a chronic dry cough, difficulty breathing, coughing up blood, and weight loss.
  • Adenocarcinoma of the pancreas: Adenocarcinoma of the pancreas can present as chronic epigastric pain, also known as pain directly below your ribcage in the upper abdomen. Other symptoms may include nausea, vomiting, jaundice, unexplained weight loss, anorexia, abnormal weakness, oily stool, swelling of the liver and spleen, and blood clots.
  • Adenocarcinoma of the prostate: This may present with trouble urinating, incomplete emptying of the bladder, the presence of blood in the urine, and low back pain.
  • Adenocarcinoma of the stomach: Poor appetite, unintentional weight loss, the pain of the abdomen, fullness in the upper abdomen after only eating a small amount of food, heartburn, indigestion, nausea, vomiting, vomiting with blood, blood in the stool, swelling in the abdomen, and anemia. Early-stage stomach cancer often does not present with symptoms.

Causes

With respect to adenocarcinoma, different types have different risk factors (including age, race, sex, and carcinogens). The one risk factor independently linked to all adenocarcinomas is smoking. Inhaled carcinogens can interact directly with your DNA, and is one potential mechanism by which cancer may be linked to multiple adverse health outcomes. Moreover, the inflammation linked to smoking exacerbates the risk of developing cancer.

Genetics also plays a part, with certain mutations linked to certain cancers. For example, BRCA mutations are associated with both breast and colorectal cancer.

Risk Factors

Environmental and lifestyle risk factors are both associated with cancer development. Different sites of adenocarcinoma have different carcinogens and risk factors. Tobacco smoking is the one risk factor that appears to be involved in most types of adenocarcinoma. 

Adenocarcinoma of the Breast

Female sex, excess levels of estrogen, early onset of menstruation, late onset of menopause, and alcohol may play a role in predisposing individuals for a greater likelihood of developing adenocarcinoma of the breast. In addition, genetic risk factors, including those of BRCA1/2, p53, PTEN, PALB2, and others, play a significant role in determining risk, as does family history.

Adenocarcinoma of the Colon or Rectum

Many hereditary colorectal cancer syndromes are hereditary, such as familial adenomatous polyposis, a rare condition involving a mutation in the APC gene, and Lynch syndrome. Lynch syndrome is the most common cause of hereditary colon cancer, including for individuals under 50. Non-Lynch syndromes with genetic risk factors include the biallelic MUTYH, BRCA1/2, PALB2, CDKN2A, TP53, and FAP. Other risk factors include personal or family history, inflammatory bowel disease, ingesting red and processed meat, smoking, or otherwise using tobacco, and alcohol.

Adenocarcinoma of the Esophagus

Alcohol has been determined as a key risk factor for the development of adenocarcinoma of the esophagus.

Lung Adenocarcinoma

Over 90% of lung adenocarcinoma cases are associated with smoking, making it a significant risk factor. Other risk factors include radiation exposure, and exposure to environmental toxins like arsenic, chromium, nickel, or polycarbonate, pulmonary fibrosis (scarring of the lung), and genetic factors.

Adenocarcinoma of the Pancreas

Risk factors include smoking, high blood sugar, high BMI, and a diet consisting of coffee, alcohol, and processed foods. As many as 10% of people with pancreatic cancer have a family history of the disease. The ABO blood type and a personal history of cystic fibrosis may also lead to a greater susceptibility to the disease.

Adenocarcinoma of the Prostate

Risks include tobacco smoking, a family history of prostate cancer, and genetic mutations such as BRCA2/1 and ATM. However, the biggest risk factor for adenocarcinoma of the prostate, also known as prostate cancer, is age. Almost all cases of prostate cancer are in males over the age of 40.

Adenocarcinoma of the Stomach

The biggest risk factor for stomach cancer is age. The median age of diagnosis is 70 years of age. Other risks include prolonged (e.g. 2-3 decades) exposure to carcinogens. Family history, diet, alcohol consumption, smoking also increase your risk. Most people who develop stomach cancer are male.

Diagnosis

Although there are a variety of tests used to screen for adenocarcinoma—including imaging studies (mammograms, CT, MRI), lab tests (cytology, PSA), and procedures (colonoscopy, thoracentesis)—the disease is definitively diagnosed is based on an examination of the cancer cells under the microscope. 

This involves a biopsy to extract a tissue sample of tissues and histology to examine the features of the cell and cell groupings. A biopsy does not mean you have cancer. A biopsy is when cells or tissue are taken from your body to be examined under a microscope. The process of closer examination using a microscope is called histology. During the biopsy, your cells or your tissue are looked at more closely to assess for signs of damage or disease. 

Biopsy

The different types of biopsy include:

  • Bone Marrow: Using a biopsy needle, your provider will withdraw a sample of bone marrow tissue. This procedure is usually done under local anesthesia.
  • Endoscopic: An endoscope is a flexible tube with a light attached, and can help to reach locations such as the lung or bladder.
  • Needle Biopsy: When a provider is able to feel a tumor through your skin, a needle biopsy can be used. Types of needle biopsies include fine-needle, core needle, vacuum-assisted, and image-guided.
  • Skin Biopsy: Most often used to diagnose skin conditions, a skin biopsy removes cells from your body’s surface.
  • Surgical Biopsy: If other biopsy methods are not an option, or if they have produced inconclusive results, a surgical biopsy is often used. During a surgical biopsy, an incision is made to remove a portion of the cells in question for further examination.

Morphology

Adenocarcinomas are relatively easy to identify and differentiate based on their morphology (physical structure). With that said, there are variations as the disease progresses. 

Morphology

Morphology refers to the study of biological form and structure.

The following are used to classify the disease:

  • Gross description: A gross description is given from a macroscopic point of view. It is based on evaluating physical structure without a microscope.
  • Frozen section: A pathologist freezes and examines the tissue. It is often used for rapid diagnosis during surgery.
  • Histologic Description: A microscopic view is used to classify the abnormality of the tissue.
  • Cytology description: After the initial diagnosis, a cytology description is used to describe further details. Like histology, cytology uses a microscope. However, cytology looks at cells, not the entire tissue. Cytology can detect small changes at the cellular level to identify cancerous or precancerous cells. They can detect the presence of abnormal cells, which may or may not be cancerous, but can increase your risk for cancer.

The differentiation of adenocarcinoma cells can predict how aggressive or indolent (slow-growing) cancer may be.

Well-Differentiated vs. Undifferentiated

Well-differentiated means the cells behave and act like normal cells, and the cancer is likely to develop slowly. Undifferentiated means they lack specialized functions and can spread rapidly. Finally, poorly differentiated means that the cells are abnormal in appearance and are likely to grow and spread rapidly.

These cellular characteristics inform the cancer stage and prognosis by assigning a tumor grade. The tumor grade helps determine the best treatment.

Staining

Staining is used in histology to show areas of importance as well as to highlight contrast. Positive stains are absorbed by the cancer cells and negative stains outline the cells. Based on how the cells respond to one or more stains, the lab can determine if adenocarcinoma is involved or some other type of cancer. 

Treatment

The treatment of adenocarcinoma can vary by location and size of the tumor, the stage and grade of the disease, and the performance status of the individual.

The general approaches include a few different types of treatment.

Chemotherapy

Chemotherapy is a drug treatment plan to eliminate the fast-growing cancer cells. Neoadjuvant refers to chemotherapy that is given prior to surgery. Adjuvant refers to chemotherapy that is administered post-surgery.

Radiation Therapy 

Adjuvant may also refer to radiation therapy given post-surgery. Palliative radiation can be given to ease suffering to improve quality-of-life.

Surgery 

Surgical resection typically provides the best chance of long-term survival in the early stages.

Immunotherapy

There are two main types of immunotherapy: active and passive. Active immunotherapy activates your body’s immune system to fight cancer cells. Cancer cells are examined to find the tumor-specific antigen. Active immunotherapies stimulate your own immune system to target these specific antigens. Examples of active immunotherapy include cancer vaccines and adoptive cell therapy. Passive immunotherapy uses components made in a lab to help your body respond to cancer in the way it should. Examples of passive immunotherapy include cytokines (proteins involved in cell signaling) and immune checkpoint inhibitors.

Checkpoint inhibitors work by acting on checkpoint proteins, which are located on immune cells. Normally, the checkpoint stops the immune cell from attacking other cells when it binds to another specific protein. Checkpoint inhibitors can block the binding process to improve the body’s immune response to cancer cells.

They may be different depending on the type of cancer:

  • Breast: There are several FDA approved immunotherapy treatments for breast cancer. These include targeted immunotherapies and immune checkpoint inhibitors.
  • Colorectal: Checkpoint inhibitors can be used when the tumor has certain gene mutations.
  • Lung: Checkpoint inhibitors are used in some cases of non-small cell lung cancer (NSCLC).
  • Prostate: Immunotherapies for prostate cancer include vaccines and checkpoint inhibitors.

Hormonal Therapy

Both breast and prostate cancer cells use hormones to grow. Hormone therapy can be used to decrease the size of a tumor prior to surgery (neoadjuvant therapy), improve chances of remission, and kill cancer cells that have returned. There are two main kinds of hormonal therapies: One blocks hormone production and the other modifies hormone behavior.

Hormonal therapy works differently for the two types of cancer:

  • Breast: Both estrogen and progesterone may cause the growth of some breast cancer cells. Breast cancers that are positive for estrogen or progesterone receptors are sometimes called hormone-receptor-positive, or HR-positive. Hormone therapy can only be used for breast cancers that have hormone receptors. Treatments can include blocking estrogen production and/or ovarian function. Other treatments involve blocking the effects of estrogen, such as anti-estrogen drugs. There are both surgical and non-surgical hormone treatments for breast cancer. 
  • Prostate: Types of therapy include lowering androgen levels through androgen-deprivation therapy, as well as drugs that lower the testosterone produced by testicles. As with breast cancer, treatments include both surgical and non-surgical options.  

Survival rates vary by the adenocarcinoma type. Women whose breast cancer has spread locally but not to distant organs have a five-year survival rate of around 85%, while men with equivalent stage prostate cancer approach 100%. By contrast, a person with equivalent stage lung adenocarcinoma has a five-year survival rate of only 35%.

A Word From Verywell

The best tool for cancer prevention is education. By identifying your personal risk (including family history), following screening guidance (including mammograms, colonoscopy, and low-dose lung CT), and taking the time to learn the signs and symptoms, you are more likely to catch cancer early when it is most treatable. 

We acknowledge that real-life struggles that you may be facing could make it hard to absorb all the information about adenocarcinoma. Please know that you are not alone, and see a doctor if you have questions.

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