Cancer interrupts the body's natural process of replacing old and damaged cells, allowing damaged cells to survive and creating an excess of new cells when they are not needed, causing tumors. The tumor's location or point-of-origin helps define a patient's type of cancer. Cancers that originate in an organ or tissue are called primary cancers.
There are two types of primary cancers; carcinomas and sarcomas. When talking about carcinomas (the most common kind of cancer) and sarcomas (a relatively uncommon form of cancer), it is important to know the similarities as well as differences that can affect a patient's cancer journey.
Where They Are Found
Carcinomas are formed by epithelial cells (the cells that cover internal organs and outside surfaces of the body) and are diagnosed based on the type of epithelial cells at the cancer site.
- Adenocarcinoma - epithelial cells that produce fluids or mucus, such as the breast, colon and prostate
- Basal cell carcinoma - cells in the lower or basal (base) layer of the epidermis (the outer layer of skin)
- Squamous cell carcinoma - (epidermoid carcinomas) epithelial cells that lie just beneath the outer surface of the skin or basal layer
- Transitional cell carcinoma - a type of epithelial tissue called transitional epithelium found in the linings of the bladder, part of the kidneys (renal pelvis), and a few other organs
Sarcomas form in the bone and soft tissues of the body including muscles, tendons, fat, lymph vessels, blood vessels, nerves and tissue around joints. Sarcomas occur most often in the arms and legs but can be present anywhere in the body.
There are more than 50 types of soft tissue sarcomas that are differentiated by the type of soft tissue at the cancer site, the type of cells, and similarity in appearance of the tumor cells to normal cells.
How They Are Diagnosed
Diagnosing a carcinoma can involve any of the following tests:
- Biopsy to remove a piece of tissue or a sample of cells from your body to determine whether the cells are cancerous and, if so, where the cancer originated
- Blood tests including a CBC (complete blood count), blood protein testing, tumor marker tests or circulating tumor cell tests
- Imaging tests including X-ray, CT scan, nuclear imaging, ultrasound, MRI, digital mammography, sentinel node mapping or virtual colonoscopy
To identify a sarcoma, a biopsy is done with samples taken from the primary tumor, lymph nodes and other potentially cancerous areas. The tissue sample then undergoes any of the following tests: immunohistochemistry, light and electron microscopy, cytogenetic analysis, FISH (fluorescence in situ hybridization) or flow cytometry to determine the presence and extent of the cancer.
How They Are Treated
Treatment options for both carcinoma and sarcoma can involve any of the following: surgery, radiation, chemotherapy, chemoradiation (combining chemotherapy and radiation), targeted therapy and immunotherapy.
Factors that can affect treatment options include:
- type of cancer;
- size, grade, and stage of the tumor;
- rate (speed) at which the cancer cells are growing and dividing;
- location of tumor in the body;
- amount of tumor removed by surgery;
- patient's age and general health;
- and status of the cancer initial occurrence or recurrence.
What Are the Risk Factors
Since carcinomas cover a broad range of cancer types, the risk factors vary. For example, cigarette smoking is the number one risk factor for adenocarcinoma that develops in the lungs, while skin cancer risk factors (basal and squamous) include long-term exposure to ultraviolet light and having a fair complexion.
Talk to your physician about your specific risk factors.