Overview of Cancer Types

Basal Cell Carcinoma

Basal Cell Carcinoma (BCC) is the most common form of skin cancer, with over two million cases being diagnosed every year in the United States alone.  This type of cancer is slow growing and rarely spreads to other parts of the body.  If left untreated, however, it can cause disfigurement by invading and damaging the surrounding nerves and tissues.  Most cases of BCC are caused by cumulative UV exposure but can also occur in areas that are protected from the sun.  

Basal cells line the deepest layer of the epidermis.  They are responsible for producing new skin cells to replace the dead ones that are regularly sloughed off.  With enough UV damage, these cells produce skin cells at an abnormal, uncontrolled rate.

BCCs often look like open sores, red patches, pearly pink growths, or scars.  Since they can take on such a variety of appearances, a biopsy is the only reliable way to make a definitive diagnosis.

Nodular:  The most common type of BCC.  Usually presents as a round, pearly growth with rolled edges that may be pigmented (brown) or have small blood vessels on the surface.

Superficial: A less common form of BCC.  Looks like a crusty red patch with a threadlike waxy border.  Is often mistaken for other skin conditions such as eczema or psoriasis. 

Fibrosing or Sclerotic:  A fairly uncommon type of BCC.  Appears ivory-white, is flat or slightly depressed like a scar, and feels firm to the touch.  Difficult to excise because it is often infiltrative and has indistinct margins.   

Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) is the second most common form of skin cancer (BCC > SCC > Melanoma).  An estimated 700,000 cases of SCC are diagnosed each year in the US, resulting in approximately 2,500 deaths.  Like BCC, SCC is mainly caused by cumulative UV exposure; however, it is more dangerous than BCC because it can spread to the lymph nodes or other organs, and in some cases be fatal.

Whereas basal cells are only found in the epidermis, squamous cells are found in both the epidermis and mucosal membranes.  Thus, SCCs can also occur on the genitals and inside the mouth, nostrils, and eyelids.

SCCs often look like scaly red patches, open sores, elevated growths with a central depression, or warts.  They may also crust or bleed.

SCC in situ (also known as Bowen’s disease):  An early form of cancer that has yet to penetrate the basement membrane and is still confined to site of the original cancer cell.  Often appears as a thick scaly red rash.

Well differentiated SCC:  The cancer has penetrated the basement membrane and is now spreading through the dermis and adjacent tissues.  It is now able to metastasize (spread to other organs and form secondary tumors there)  These often appear as very thick, crusty lesions with tops that may fall off but invariably grow back.

Aggressive, poorly differentiated SCC:  The most dangerous type of SCC because it grows very quickly and has a greater tendency to metastasize.  They have a wide variety of appearances (soft, hard, open sores, etc.)


Actinic keratosis:  Common sunspots, the least dangerous type of SCC (more of a pre-cancer).  The surrounding skin often looks sun damaged (blotchy, freckled, and wrinkled).

Melanoma

Melanoma is less common than other skin cancers but is by far the most dangerous if not found early, causing the majority (75%) of deaths related to skin cancer.  More than 76,000 cases of melanoma are diagnosed in the US every year.  If the cancer is found in the early stages, it can usually be removed with surgery.  If the melanoma has spread, it will need to be treated with chemo- and immunotherapy, or radiation therapy.

 

Melanomas begin in the melanocytes (pigment-producing cells) and are caused by UV damage and genetic factors.  They may appear suddenly on the skin or develop from an existing mole.  Early signs of melanoma are summarized by the mnemonic “ABCDE”:

Asymmetry

Borders (irregular edges that are notched, uneven, or blurred)

Color (different shades of brown, black, or tan)

Diameter (>6mm, the size of a pencil eraser)

Evolving over time