What is carcinoma?
Click Here to Manage Email Alerts
The most common type of cancer in humans is carcinoma.
Carcinoma begins in the epithelial tissue of the skin or the tissue that lines internal organs, such as the liver or kidneys.
Carcinoma is tumor tissue derived from putative epithelial cells whose genome has become altered or damaged, causing the cells to transform and show abnormal malignant properties.
Malignant tumors made up of transformed cells whose origin or developmental lineage is unknown but have specific molecular, cellular and histological characteristics typical of epithelial cells are also characterized as carcinoma.
Organ sites
Organ sites frequently affected by carcinomas include:
- lung;
- breast;
- prostate;
- bladder;
- colon and rectum; and
- pancreas.
Carcinoma is diagnosed using biopsy, such as shave or punch biopsy, fine-needle aspiration, excisional or incisional biopsy, or surgical removal of a single node. A pathologist then analyzes the sample under a microscope to identify molecular, cellular or tissue architectural characteristics of epithelial cells.
Types of carcinomas
The different epithelial cell types of carcinoma are:
- adenocarcinoma, which forms in cells that produce fluids and mucus;
- basal cell carcinoma, which forms in the basal cells in the deepest layer of the epithelium;
- squamous cell carcinoma, which forms in the flat squamous cells in the top layer of the epithelium; and
- transitional cell carcinoma, which forms in the transitional epithelium or urothelium.
Basal cell carcinoma and squamous cell carcinoma are the most common and second most common types of skin cancer, respectively. Other common types of carcinomas include:
- renal cell carcinoma, which is the most common type of kidney cancer and develops in the lining of the kidney tubules;
- ductal carcinoma in situ, which is the most common type of breast cancer and is confined in the lining of the milk ducts; and
- invasive ductal carcinoma, which is cancerous cell growth in the duct lining and tissue of the breast.
Risk factors for all the types of carcinomas include age, alcohol and tobacco use, exposure to ultraviolet radiation from the sun or tanning beds, and chemical or environmental irritants. Other factors that increase risk include obesity, diet, physical inactivity and history of certain infections, such as HPV.
Carcinoma in situ
Carcinoma in situ is the term for a small, localized carcinoma that has not yet invaded through the epithelial basement membrane to restrict the carcinomatous cells from adjacent normal cells. This type of carcinoma is preinvasive but not premalignant, and is generally the earliest form of cancer, considered stage 0.
Carcinoma in situ almost always continues to grow and progress until it infiltrates and penetrates into and through the basal membrane or other structures. Once the basal membrane or other structures are penetrated, these lesions are invasive carcinomas.
Cure rates for carcinoma in situ may be 100% with removal by surgical resection, cryotherapy, laser ablation or other local treatment before metastasis.
Adenocarcinoma
Adenocarcinoma initiates in the secretory or glandular cells of the body. Glandular cells are a part of the tissue that lines certain internal organs. These cells create and release substances within the body, such as digestive juices or mucus. Adenocarcinomas are most often found in the breast, esophagus, colon/rectum, lungs, stomach, pancreas and prostate.
Carcinomatosis
Carcinomatosis occurs when a cancer has spread throughout the body or when a cancer has spread to a significant region of the body.
The most common forms of carcinomatosis are leptomeningeal, pulmonary lymphangitic and peritoneal. Peritoneal carcinomatosis occurs when a cancer metastasizes and manifests in carcinomas of the gastrointestinal tract and ovaries. These cancers include pancreatic, colon, gallbladder, appendix, ovarian and rectal.
Treatment
Treatment of carcinoma differs depending on type and location.
Possible treatments include:
- chemotherapy;
- radiation;
- surgery;
- targeted cancer therapy; and
- biologic therapy.
- Support groups are also available to help patients cope with the anxiety that often accompanies a cancer diagnosis.
Additional information can be found at the following websites:
www.cancer.gov/about-cancer/understanding/what-is-cancer
www.cancer.net/navigating-cancer-care/cancer-basics/what-cancer
www.cancercenter.com/carcinoma-in-situ
my.clevelandclinic.org/health/diseases/21652-adenocarcinoma-cancers
my.clevelandclinic.org/health/diseases/22182-carcinomatosis-carcinosis
www.mayoclinic.org/diseases-conditions/basal-cell-carcinoma/symptoms-causes/syc-20354187
www.mayoclinic.org/diseases-conditions/squamous-cell-carcinoma/symptoms-causes/syc-20352480