The Rise in Incidence
Fashion has dictated for the last 50 years that tanned skin is desirable. Unaware of danger, we as a society have exposed more unprotected skin to ultraviolet (UV) radiation in direct sunlight and/or tanning beds than is good for us. UV radiation damage in the skin is invisible, and it takes years before visible changes appear, making sun protection easy to ignore. Sunburns (radiation burns, actually) are particularly bad for skin cells, causing permanent DNA mutations. These mutations lie dormant for decades. Sunburns suffered at earlier ages have the greatest impact on the number and severity of skin cancers. After a latent period of years, a cell with a DNA mutation is triggered (often by UV radiation) into unregulated growth. In medical terms, ultraviolet radiation is known as a "complete carcinogen," capable both of initiating genetic mutations and of promoting the uncontrolled growth of mutant cells.
The incidence of the three main skin cancers has risen rapidly in recent years, roughly in parallel with the societal trend toward more unprotected time in direct sunlight. Basal cell carcinoma (BCC) is already the most common cancer in humans, and the numbers continue to rise. Squamous cell carcinoma (SCC) is less common than BCC, but more likely to spread through the body (metastasize). New cases of malignant melanoma, the worst of the three skin cancers, are appearing faster than any other cancer in humans. Fortunately, all three skin cancers are quite curable when caught and treated early. We encourage you to inform yourself and ask questions of your physician. A good place to start is the Skin Cancer Foundation’s website: www.skincancer.org. This link will take you off-site.
The Treatment of High Risk Cancer
The three main skin cancers are basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and malignant melanoma. This discussion concerns BCC and SCC, of which new cases in the United States alone each year number almost a million, BCCs outnumbering SCCs about four to one. Fortunately, both are quite curable, especially when treated early and properly.
BCCs and SCCs are divided into low risk and high-risk types, based on their location and tendency to re-grow after treatment. Low risk tumors far outnumber the high-risk type. Low-risk cancers are smaller, more localized, easier to treat, and usually don't come back (recur) after treatment. Multiple satisfactory treatment options include creams, scraping and cautery therapy, and routine excision and suturing. Dermatologists and family physicians treat many, many low-risk BCCs and SCCs, as do some plastic surgeons and dermatologic surgeons.
High-risk BCCs and SCCs, on the other hand, tend to invade deeper or wider in the skin. They can be recognized by their larger size and longer duration, facial location, aggressive growth pattern under the microscope, or re-growth (recurrence) after previous treatment. These tumors can infiltrate the skin almost undetectably, sometimes becoming quite large before they ever show on the surface. They frequently grow asymmetrically (in one direction), and may track along nerves or cartilage. They often recur after insufficient treatment (or, more accurately, are not completely removed by the treatment). Recurrent BCCs and SCCs are always high-risk. The most successful treatment for high-risk skin cancers is Mohs surgery, named after the surgeon who pioneered the technique over 50 years ago.
Mohs surgery is the treatment of choice for high-risk skin cancer, because it consistently offers the highest cure rate (lowest recurrence), and leaves the smallest skin defect after the cancer is gone. The reason is that the complete surgical margin of the excised tissue is examined immediately under the microscope by the Mohs surgeon and mapped. The tissue is prepared somewhat like unwrapping a cupcake, then flattening out and examining the clean side of the paper (the cupcake represents the cancer, the paper the surgical margin). The technique allows sequential removal of thin layers of only cancer-involved skin, sparing normal skin, and possibly offering a more elegant reconstructive option. When the margin around a cancer is clear, that cancer is gone with a very high, reproducible degree of accuracy. Reconstruction to restore the normal appearance follows complete cancer removal, usually on the same day.
When Mohs surgery is not available, routine wide excision yields the second best cure rate for high-risk skin cancers, especially if frozen-section margin control is used. Plastic surgeons do many of these procedures. However, whereas Mohs surgeons are extensively trained in microscopic skin cancer pathology, plastic surgeons rely on a pathologist. The pathologist examines cross-sections of the tissue margin (slices of bread are cross-sections of a loaf), to estimate whether or not the surgical margins are clear of cancer. This is quite different from actually examining the complete surgical margin, and is the main reason for the lower cure rate with routine wide excision. Microscopic tumor extensions may not show on the microscope slide if a cross-section is not in exactly the right place. To compensate, larger margins of normal skin around the cancer are typically excised with routine wide excision than with Mohs surgery. This creates a larger skin defect, with more challenging and limited repair options.
Choosing among physician specialties for a surgeon specializing in skin cancer removal and reconstruction can be confusing. For example, will a plastic surgeon do better reconstructive work than a dermatologist, or Mohs (dermatologic) surgeon, as someone may have said? Not necessarily. It depends on the individual surgeon, not the title. Factors to consider are training, experience, practice focus, skill level, and “track record” of the surgeon. The most reliable sources of information on the best skin cancer surgeons are your physician or local medical society.
This article contains more information about the high cure rate of Mohs surgery, and the Mohs College explains the procedure in depth. Another good article, available here, was recently printed in Newsweek.