Aim of the basal cell carcinoma section: After reviewing this chapter the reader should be more familiar with basal cell carcinoma. The different forms of basal cell carcinoma, man's most common skin cancer, will be discussed as well as various types of skin cancer surgery and other therapies currently in use to treat basal cell carcinoma. Treatments for basal cell carcinoma including liquid nitrogen, Mohs Surgery, plastic surgery, reconstructive surgery and laser surgery are clearly explained. Methods to detect basal cell carcinoma including naked eye detection and skin biopsy methods will also be discussed in-depth. Suggestions and new findings regarding sunscreens and their relationships to basal cell carcinoma are made.

......Basal-cell carcinoma (BCC) is humankind's most common malignancy or cancer. Nearly one million Americans will develop a BCC this year alone. Currently, one out of every three new cancers in America is a skin cancer. Although anyone with a history of sun exposure can develop BCC, people who are at highest risk have fair skin, light hair and blue, green or gray eyes. Those who work or enjoy the outdoors are also susceptible. In fact, sun-induced mutations are found in over 90% of BCC's studied.

......When removed early, most BCC's are easily treated. The larger the tumor grows, the more it invades and the more surgery or treatment is required. Although basal-cell cancer hardly ever spreads to other parts of the body, it can easily destroy neighboring tissues and structures. This can result in the loss of an eye, an ear, a nose or part of a lip. Since all surgery involves cutting or disturbing the skin to the level of the dermis (leather layer), some scarring is inevitable if a BCC is to be treated properly. If a cancer is removed when it is small, the resulting scar is usually small and, therefore, cosmetically acceptable and may be unnoticeable to the public. If a tumor is large to the naked eye or has grown large invisibly under the skin, more extensive reconstructive surgery involving a skin graft or flap may be needed to repair the hole resulting from the removal of the cancer. It is also of concern that BCC's are among several tumors known to invade the perineural (around the nerve) space. Once basal- or squamous-cell cancer tracks along a nerve in this perineural space, the cancer cells have direct access to the brain or spine. The results can be devastating. Fortunately, this phenomenon is rare with BCC and only occasionally found with squamous-cell cancer (SCC).

......BCC may be classified/described both clinically (how it looks to the naked eye) and histologically (how it looks under the microscope) by numerous terms, confusing to both patients and some doctors. The five most typical features of BCC are quite different from each other. Often, two or more signs are present in one BCC. BCC can even look like common skin rashes such as psoriasis or eczema. Therefore, it is best to have a well-trained dermatologist examine any unusual skin spot to be sure.

These Warning Signs were taken from a Skin Cancer Foundation brochure and are an excellent patient reference.

......Another system of five major clinical (naked-eye) classifications include:

1.	Nodulo-ulcerative: looks like a glob or ball, sometimes ulcerating (rotting) in the center because the center cells are too far away from a good blood supply; usually this type has only a few roots if it is not a mixed tumor.
2.	Pigmented: usually has a dark color, especially in people with a Hispanic or Italian genetic background.
3.	Morphealike or fibrosing: roots go deep into the surrounding tissue.
4.	Superficial/multicentric: roots of tumor grow along the surface of the skin; usually so thin as to be invisible to the naked eye.
5.	Fibroepithelioma: tag-like growth, usually occurring on the lower back.

......The histologic (microscopic) classifications of BCC are made based on how much the BCC looks like the glands or different tissues of the skin (appendages) under the microscope. Histologic classifications of BCC include:

......The classical BCC has blood vessels and looks pearly. But the classical represents only a fraction of the ways basal-cell cancer can look. For example, a basal cell may spread far beyond the edges of what is seen as the normal-looking skin. Therefore, we must consider that BCC can look even like normal skin. Although it is not common, BCC that resembles normal skin may represent two percent of all BCC's. It is impossible for patients to recognize all of the different types of BCC, but studying the photos will help avoid missing the obvious ones. Additionally, keeping in mind that an area that remains red or raw or does not heal in three or more weeks should alert patients. A spot that does not heal in a man's shaving areas may indicate weak tumorous tissue that is being uncovered by the act of shaving.

......Both clinical and histologic classifications are helpful not only in studying individual lesions but also in planning the method of treatment best suited to the individual patient. The author believes that consideration of the clinical classifications and microscopic confirmation are extremely important in predicting how a BCC will behave or grow, and how to counter it. Keep in mind, as we will discuss in a few paragraphs, that several subtypes may be present in one tumor, further confusing things! What if the biopsy is taken only in the area of the tumor where just one subtype is present? This frequently occurs.

......Some BCC's have a significant potential to recur, disfigure and metastasize. Aggressive histologic subtypes of BCC are considered "high risk." High-risk BCC tumors are ones that are likely to come back after treatment or, if they are left untreated, tend to destroy many nearby body tissues and structures. Other factors that may indicate the tendency of a BCC to recur (return or fail treatment) are tumor location, size and any previous failed treatments.

......The total fraction of aggressive subtypes (morpheaform, infiltrative, micronodular) of BCC is slightly less than 20% (1 in 5 chance) of all BCC's. Dermatologists have long recognized the infiltrative/morpheaform and superficial multicentric subtypes as more difficult to cure; these are thus considered "more aggressive." It is important to ask your doctor to see your biopsy report. Note whether the words infiltrative, morpheaform or multicentric are present. The cure rates for these types of BCC's will vary with removal method and body location. For example, a morpheaform tumor on the chest may be removed using Mohs surgery with 99% success and 97% success with other removal methods. However, a morpheaform tumor on the nose may be removed using Mohs surgery with 99% success and only 80% success with other removal methods. A greater number of Mohs stages (layers of tissue removed in a special highly accurate skin-cancer surgical method) are usually needed to remove completely tumors that are of the infiltrative, morpheaform, micronodular and mixed BCC subtypes (also usually considered aggressive). Another factor less related to subtype that may also indicate the aggressiveness of a BCC is the number of blood vessels present in the tumor (vascularization).

......Alternatively, various subtypes of BCC may have other properties. For example, superficial and nodular BCC tend to occur on sun-exposed areas. Fibroepitheliomas occur most commonly on the lower back. Superficial multicentric BCC may occur in significantly younger patients than other BCC subtypes. Immune-suppressed (organ transplant, etc.) individuals have a higher frequency of the infiltrative subtype.
......The results of studies of new treatments for BCC depend heavily on the mix of subtypes present in the study. For example, a study in the late 1990's revealed the relatively new aminolevulinic acid - photodynamic therapy yielded only a 50% cure rate against superficial BCC versus an 83% cure rate against nodular BCC in one study. (Calzavara-Pinton) Researchers who do not take these factors into account when studying new or old established treatments may draw mistaken conclusions. Unfortunately, this situation is not uncommon.
......Many factors influence how basal-cell carcinoma will behave, including how the cancer looks under the microscope. Even within a particular skin cancer, a given biopsy may miss the worst portion of the tumor and give a "false read." Nonetheless, for basal-cell carcinoma, the location of the tumor may have a great bearing on how the tumor develops and where it will send roots.

......Basal cells have an enzyme (protein) that digests collagen, called collagenase (dissolver of collagen). Collagen is that material that makes up the dermis (leathery layer) of the skin that sits just below the epidermis (top layer). There is very little blood supply in fat or even in collagen, for that matter. The author believes that the vast majority of basal-cell cancers are inhibited in growth in the vertical (or deep) direction by the presence of fat because fat is hard for BCC's to dissolve and has no blood supply to feed upon; note, the presence of fat does little to prevent the horizontal (width) spread. Note in the diagram below that the areas of the face considered to be at the highest risk have the least fat and access is available from the dermis directly into bone, muscle or tissues higher in collagen content than fat.