Introduction

The non-melanoma skin (NMS) cancers, principally basal cell and squamous cell carcinomas, are very common but rarely fatal.

Histology, classification and diagnosis

Basal cell carcinomas are usually found on the face above a line drawn from the angle of the mouth to the ear lobe. Although slow growing, and almost never mestastasizing, these cancers, if neglected, can result in large ulcers hence the term ‘rodent ulcer’. Squamous cell carcinomas can occur on any part of the body, especially in the dorsum of the hand, or on the legs (notably in Africa). Other skin cancers, mainly arising from sweat glands, are very rare.

Descriptive epidemiology

Incidence

The incidence of NMS tumors shows wide variation. The true incidence is difficult to determine in view of their high frequency, low lethality and the fact that an individual may have several over a lifetime. Many cancer registries do not record basal cell carcinomas, which are also often under reported.

The highest rates of NMS cancer recently reported are from Tasmania in Australia (167.2 in males and 89.3 in females) and from British Columbia in Canada (109.1 in males and 75.5 in females). In El Paso in Texas, after a special effort to assess the true incidence, rates were as high as 144.9 in ‘Anglo’ males and 73.3 in ‘Anglo’ females (Waterhouse et al., 1976). Rates in the 50 to 60 range are observed in males in Brazil, Colombia and Switzerland.