Adenocarcinoma

Adenocarcinoma may be aggressive depending on the organ involved. Some adenocarcinomas grow slowly and remain localized for a long time, while others spread quickly and have a higher risk of metastasizing to other parts of the body.  

For example, adenocarcinoma of the lung is the leading cause of cancer deaths in the United States. Lung adenocarcinoma is fairly aggressive and results in a 5-year survival rate of 60% if there is no metastasis at the time of diagnosis. If the cancer has metastasized by the time of diagnosis, the 5-year survival rate is reduced to around 6 to 10%. In contrast, breast adenocarcinoma is generally less aggressive with a 5-year survival rate of about 99%, if the cancer has not metastasized. This is in part because breast cancers can be detected earlier using widespread screening programs, whereas other cancers, such as lung cancer, are typically detected later in the disease course due to poorly defined, non-specific symptoms and screening methods.  

Adenocarcinoma develops from epithelial cells with glandular differentiation, meaning that they have a gland-like structure or secretory function. These cells undergo genetic mutations that allow them to start growing out of control, forming a mass or tumor. Notably, mutations in the KRAS, EGFR, BRAF, HER2, TP53, APC, and BRCA genes have been implicated in different forms of adenocarcinomas, depending on the organ affected. These genetic variants may lead to dysregulation of signaling pathways that regulate cell growth and division, resulting in uncontrolled cell proliferation.  

Esophageal Adenocarcinoma 

Risk factors for adenocarcinoma depend on the organ affected. Esophageal adenocarcinoma is associated with tobacco and alcohol use, as well as a condition known as Barrett esophagus, where acid refluxes from the stomach into the esophagus, causing irritation and cellular damage.  

Lung Adenocarcinoma 

The most common causes of lung adenocarcinoma include smoking tobacco; secondhand smoke exposure; exposure to toxins, such as radon, air pollution, and asbestos; arsenic consumption through drinking water; previous radiation to the lungs; and a genetic predisposition to lung cancer.  

Breast Adenocarcinoma 

Breast cancers may be inherited through genetic mutations such as the BRCA1 and BRCA2 gene. Risk factors for breast cancer include increased age, obesity, early menarche, and late menopause.   

Pancreatic Adenocarcinoma 

Pancreatic adenocarcinoma may be due to smoking, diabetes mellitus, chronic pancreatitis, and obesity. 

Stomach Adenocarcinoma 

Stomach cancer can be caused by chronic bacterial infection by Helicobacter pylori, tobacco use, and genetic inheritance of specific genes such as CDH1, MLH1, and MSH2.  

Colorectal Adenocarcinoma 

Colorectal cancer is associated with diets low in fiber and high in fat, a family history of colorectal cancer, inherited syndromes (e.g., Lynch syndrome, familial adenomatous polyposis) and a personal history of irritable bowel disease.  

Prostate Adenocarcinoma 

Lastly, prostate cancer is attributed to obesity, older age, and increased levels of testosterone.  

The signs and symptoms of adenocarcinoma vary depending on the organ affected. Unexplained weight loss due to cancerous cells constantly dividing and using the body’s energy can be a non-specific indicator of a malignant process, such as adenocarcinoma metastasis. Other general symptoms include weakness or malaise, night sweats, and decreased appetite.  

Esophageal adenocarcinoma   

Specifically, esophageal adenocarcinoma presents with difficulty swallowing, heartburn, pain or pressure in the chest, and hoarseness of voice.  

Lung adenocarcinoma 

Those with lung adenocarcinoma may experience a persistent cough, chest pain, difficulty breathing, blood in the sputum (i.e., hemoptysis), and wheezing if the tumor affects the bronchi.  

Breast adenocarcinoma 

Adenocarcinoma of breast tissue can present with a new lump in the breast or armpit; swelling of the breast; skin dimpling overlying the breast; breast or nipple pain; nipple retraction; red, dry or flaky skin of the breast; and nipple discharge.   

Pancreatic adenocarcinoma 

Those with pancreatic cancer may experience back pain, nausea and vomiting, bloating, loss of appetite, and fatty stools.  

Stomach adenocarcinoma 

Stomach adenocarcinoma typically presents with abdominal pain, bloating, and the sensation of being full without ingesting much food.   

Colorectal adenocarcinoma 

Colon adenocarcinoma presents with changes in bowel habits, abdominal pain, blood in the stool, anemia, and unexplained weight loss.  

Prostate adenocarcinoma 

Lastly, prostate adenocarcinoma may present with erectile dysfunction, blood in the urine (i.e., hematuria), and the frequent need to urinate (i.e., polyuria).  

Diagnosis of adenocarcinoma usually begins with a medical history and physical examination followed by imaging and laboratory testing to narrow down the diagnosis. 

Specific blood testing may be ordered depending on the suspected organ affected (e.g., a PSA blood test for prostate adenocarcinoma). Imaging of the entire body or certain parts of the body through computed tomography (CT) scan or magnetic resonance imaging (MRI) may be used. Imaging can help the clinician determine whether there is an adenocarcinoma or another underlying pathology causing the symptoms, which organ is affected, and whether the cancer has spread. Lastly, a biopsy of the tumor can be obtained to confirm the diagnosis of adenocarcinoma and determine the grade, which is the degree of abnormality in cellular shape and growth that correlates with its aggressiveness. In certain tumors, such as breast adenocarcinoma, a biopsy of surrounding lymph nodes can help determine spread, or metastasis, of the tumor.  

In addition to a timely and accurate diagnosis, screening is important for those at risk for adenocarcinoma. Individuals at high risk for lung adenocarcinoma (e.g., smokers) may receive regular lung cancer screenings through low-dose CT scans. The US Preventive Services Task Force (USPSTF) recommends that genetic females between 50-74 years old undergo a mammogram every 2 years to detect breast cancer. Those at a higher risk (e.g., BRCA mutations or a strong family history) may be recommended more frequent or earlier screening, often including additional methods like breast MRI. Additionally, individuals without risk factors for colorectal cancer are recommended to start regular screening at age 45 using colonoscopies or fecal immunochemical test (FIT), which is a non-invasive test that detects blood in the stool. For colorectal cancer, screening can be stopped at age 75 if previous screenings have been regular and normal, or based on individual health and preferences.