Types (Continued)

Basal cell carcinomas (BCC) are the most common. They present on sun exposed areas of the skin, especially the face. They rarely metastasize, and rarely causes death. They are easily treated with surgery or radiation. Squamous cell carcinomas(SCC) are common, but much less common than basal cell cancers. They metastasize more frequently than BCC's. Even then, the metastasis rate is quite low, with the exception of SCC's of the lip, ear, and in immunosuppressed patients. Melanomas are the
least frequent of the 3 common skin cancers. They frequently metastasize, and are deadly once spread.

Less common skin cancers include: Dermatofibrosarcoma protuberans,Merkel cell carcinoma,Kaposi's sarcoma, keratoacanthoma, spindle cell tumors, sebaceous carcinomas, microcystic adnexal carcinoma, merkel cell carcinoma, Pagets's disease of the breast, atypical fibroxanthoma, leimyosarcoma, and angiosarcoma

The BCC and the SCC often carry a UV-signature mutation indicating that these cancers are caused by UV-B radiation via the direct DNA damage. However the malignant melanoma is predominantly caused by UV-A radiation via the indirect DNA damage. The indirect DNA damage is caused by free radicals and reactive oxygen species. Research indicates that the absorption of three sunscreen ingredients into the skin, combined with a 60-minute exposure to UV, leads to an increase of free radicals in the skin.

Skin cancer as a group

Many laymen and even professionals consider the basal cell carcinoma (BCC), the squamous cell carcinoma (SCC) and the malignant melanoma as one group - namely skin cancer. This grouping is problematic for two reasons:

• the mechanism that generates the first two forms is different from the mechanism that generates the melanoma. The direct DNA damage is responsible for BCC and SCC while the indirect DNA damage causes melanoma.
• the mortality rate of BCC and SCC is around 0.3 causing 2000 deaths per year in the US. In comparison the mortality rate of melanoma is 15-20% and it causes 6500 deaths per year.^:29,31

Even though it is rare, malignant melanoma is responsible for 75% of all skin cancer related death cases.

While sunscreen has been shown to protect against BCC and SCC it may not protect against malignant melanoma. When sunscreen penetrates into the skin it generates reactive chemicals. It has been found that sunscreen use is correlated with malignant melanoma. The lab-experiments and the epidemiological studies suggests that sunscreen use correlates with melanoma incidence. The question that has to be asked is: "Are sunscreen users also the ones with the highest lifetime exposure to ultraviolet lights?" or are sun screens tumor promoters or carcinogens themselves. Logics might suggest that sunscreen users also are the ones most likely to be burned or have been burned by sun light. If it is true that some suncreen induces the formation of skin cancers, the physical sunscreen which are metallic in nature (zinc and titanium) are likely safer and likely to be inert. In the past, most sunscreens were chemical blockers (benzones, etc.).

Signs and symptoms