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In contrast to most skin cancers, melanoma has a strong tendency to become invasive and metastasize. Because there is no good treatment for metastatic melanoma, even small cancers often prove fatal if not detected early. Melanoma allowed to invade the subcutaneous tissue is associated with a five-year survival of only 44%. As a consequence, the problems posed by its rising incidence have been especially severe. The irony of these grim statistics is that few cancers provide a greater opportunity for early discovery and cure. Cutaneous melanoma is not only located in the open where it is readily observed, but typically undergoes a "radial growth" phase prior to metastasis. Radial growth is a specific biological phase of development rather than a geometric description. Cells actually grow in all directions from a malignant focus, but those growing toward the skin surface slough off, while those attempting to invade the dermis are destroyed by immune surveillance. Thus the net growth is superficial and circumferential, gradually increasing the area of the lesion and changing its coloration.

For the early detection of melanoma screening measures must focus on two primary tasks: 1) detection of lesion changes indicative of the radial-growth stage of malignancy and 2) alerting the patient and physician to the existence of a new lesion on the skin. In practice this is a frustratingly difficult challenge. The typical scenario is that a high risk patient is charged with personally monitoring his or her own skin lesions with an eye out for change. When the patient sees a physician the patient is then asked to identify any changed lesions. The Western Research Company, Inc. experience after more than five years of working with a specific population of high risk patients with a large number of moles or dysplastic nevi is that they have nearly given up trying to follow changes. The problems they most frequently cite are the following: 1) "I have too many moles to be able to follow them.", 2) "I can't see most of my moles." (i.e. they are on parts of the body not readily viewable), and 3) "I try to follow my moles, but I am not always certain whether they are new or not."

There have been several studies which indicate the importance, not only of dermatological screening, but of whole body dermatological screening. In fact, the above referenced New York City screening program concluded that over 90% of the malignant melanomas found would have been missed in partial, as opposed to whole body, screening. Implementing a screening program which encourages and facilitates effective whole body screening would represent a significant improvement in public health.

     Western Research Company, Inc. has developed DermAlert®, a microcomputer based digital imaging system which has been optimized for early detection of new and changed skin lesions. This is an easy to use system which allows the capture of registered pairs of images of the skin (as obtained in two or more examinations typically separated in time by months or years), and to alternately display those images on a computer monitor at a user selected frequency .

When these registered images are alternately displayed, or "blinked", there is a remarkably strong visual impression of any change in the images. Those moles and lesions which have not changed during the intervening time period between the two image captures, appear unchanged in the images. A new feature, however, will appear to flash in the image, literally blinking on and off. It has been our experience that even very low contrast features are highly detectable by this appearance. On the other hand, those lesions or features which have changed size in the interim, appear to "pulsate" in the image display. This is also a highly stimulating visual cue. It is the remarkable ease with which changed lesions can be identified with this type of approach that makes it particularly intriguing as a screening tool.