CUTANEOUS SQUAMOUS CELL CARCINOMA

Cutaneous squamous cell carcinoma (SCC) is the most common cancer arising from malignant proliferation of the keratinocytes of the epidermis. Treatment of cutaneous SCC is always indicated since progression of the tumor may lead to very extensive local tissue destruction or metastasis resulting in significant morbidity or death. Early treatment provides the best opportunity to cure cutaneous SCC.

In contrast to basal cell carcinoma (BCC), which rarely metastasizes, around 2 to 5 percent of cutaneous SCCs metastasize to regional lymph nodes or more distant sites. The approach to treatment is dependent upon the presence or absence of tumor features and patient characteristics that are predicted for an increased risk for aggressive tumor behavior. Cutaneous SCCs that do not have high-risk features have low frequencies of recurrence and metastasis. The histology will gave the most valuable information.

Histologically, it arises from the uncontrolled multiplication of cells of epithelium, or cells showing particular cytological or tissue architectural characteristics of squamous cell differentiation, such as the presence of keratin, tonofilament bundles, or desmosomes, structures involved in cell-to-cell adhesion.

All squamous cell carcinoma lesions are thought to begin via the repeated, uncontrolled division of cancer stem cells of epithelial lineage or characteristics. Accumulation of these cancer cells causes a microscopic focus of abnormal cells that are, at least initially, locally confined within the specific tissue in which the progenitor cell resided. This condition is called squamous cell carcinoma in situ, and it is diagnosed when the tumor has not yet penetrated the basement membrane or other delimiting structure to invade adjacent tissues. Once the lesion has grown and progressed to the point where it has breached, penetrated, and infiltrated adjacent structures, it is referred to as "invasive" squamous cell carcinoma. Once a carcinoma becomes invasive, it is able to spread to other organs and cause a metastasis, or "secondary tumor", to form.

Most squamous cell carcinomas result from prolonged exposure to ultraviolet (UV) radiation, either from sunlight or from tanning beds or lamps. Avoiding UV light as much as possible is the best protection against all types of skin cancer. Sunscreen is an important part of a sun safety program, but by itself doesn't completely prevent squamous cell carcinoma or other types of skin cancer.