Two terms that often arise in discussions about growths in the body are “adenoma” and “adenocarcinoma.” Both originate from glandular tissue, found throughout the body and responsible for producing substances like hormones or digestive fluids. The fundamental distinction between these terms lies in their behavior: an adenoma is a non-cancerous growth, while an adenocarcinoma is a cancerous one. This difference significantly impacts how these growths are approached and treated.
Understanding Adenomas
An adenoma is a benign tumor that develops from epithelial tissue with glandular characteristics. These growths do not spread to surrounding tissues or other parts of the body. Adenomas are slow-growing, but their cells show changes in their architecture, a condition known as dysplasia or atypia.
Adenomas can appear in many glandular organs, including the colon, thyroid, pituitary gland, and adrenal glands. In hollow organs like the digestive tract, an adenoma may grow into the lumen, forming an adenomatous polyp. Some adenomas have the potential to become malignant over time.
Understanding Adenocarcinomas
An adenocarcinoma is a malignant tumor that arises from glandular epithelial cells. Unlike adenomas, these tumors display uncontrolled cell growth. Adenocarcinomas are characterized by their aggressive nature and ability to invade nearby tissues and spread to distant sites through the bloodstream or lymphatic system, a process known as metastasis.
Adenocarcinomas are a common type of cancer and can affect various organs throughout the body due to the widespread presence of glandular tissue. Common locations include the breast, prostate, lung, colon, and pancreas. These tumors exhibit rapid growth and show cellular atypia and abnormal cell division when examined microscopically.
Key Differences and Significance
The primary distinction between an adenoma and an adenocarcinoma lies in their behavior and potential for harm. An adenoma is benign and does not invade surrounding tissues or metastasize. Its cells may show abnormal growth patterns, or dysplasia, but they do not exhibit the uncontrolled proliferation seen in malignant cells.
In contrast, an adenocarcinoma is malignant, capable of invading local tissues and spreading to distant organs. At a cellular level, adenocarcinomas display poorly differentiated cells with abnormal morphology, whereas adenomas consist of well-differentiated cells that more closely resemble normal glandular tissue. This difference in malignancy impacts patient prognosis and treatment strategy. The growth rate also varies, with adenomas growing slowly, while adenocarcinomas can grow more rapidly.
How Adenomas Can Progress to Cancer
Adenomas, although benign, can undergo malignant transformation, developing into adenocarcinomas. This progression involves a series of genetic and epigenetic alterations within the cells of the adenoma. For instance, in colorectal cancer, this transformation is described as the adenoma-carcinoma sequence, where normal epithelial cells progress through dysplastic stages to adenomas and then to carcinomas.
Several factors influence this progression. The size of the adenoma is a contributing factor, with larger adenomas having a higher potential for malignant change. The degree of dysplasia, or abnormal cell growth within the adenoma, is also a significant indicator of progression risk. Specific genetic mutations, such as those in the APC, KRAS, and TP53 genes, accumulate over time and drive the transformation from an adenoma to an adenocarcinoma. Regular monitoring and removal of certain adenomas are important preventive measures to interrupt this progression.
Detection and Next Steps
The detection of both adenomas and adenocarcinomas involves screening procedures and diagnostic tests. For colorectal growths, screening colonoscopies are used, which can identify and remove adenomatous polyps before they become cancerous. Other screening methods for colorectal cancer include high-sensitivity guaiac fecal occult blood tests or fecal immunochemical tests, and stool DNA-FIT tests.
When a suspicious growth is found, a biopsy is performed to obtain a tissue sample for microscopic examination. This histological analysis provides a definitive diagnosis, allowing pathologists to determine whether the growth is a benign adenoma or a malignant adenocarcinoma. The subsequent steps depend on this diagnosis; adenomas may be observed or surgically removed, while adenocarcinomas require more extensive cancer treatments, which can include surgery, chemotherapy, or radiation therapy.