In contrast to other parts of the world, melanomas are not among the most frequently diagnosed cancers in Colombia or South America, which is probably the reason why they are not studied as intensely in this continent as in other parts of the world. However, the few studies that have investigated time trends in cancer incidence and/or mortality in the region have observed steady increases in trends over the past decades.
In predominantly Caucasian populations, melanomas are amongst the most frequently diagnosed tumors, exhibiting a very sharp and continuous increase in incidence since the 1950s. Fortunately, in these high incidence areas of the world, melanomas are increasingly being diagnosed earlier, reducing the case-fatality substantially. Five-year relative survival rates of all melanomas are around 90% in northwestern Europe, the USA and Australia. Moreover, new treatment options were recently introduced, thus also improving prognosis for advanced stage melanomas.
In Colombia, melanoma is still a rare tumor, being diagnosed in approximately 4.5/100 000 individuals per year. Unfortunately, its case-fatality is relatively high, making melanoma a much more fatal cancer here than in the highincidence areas of the world.
Although melanomas are often considered to be one entity of cancer, their characteristics, prognosis, and —proba bly also— risk factors differ substantially by histological sub type, as well as by stage at diagnosis. In this issue of the databases of the Instituto Nacional de Cancerología (INC) were analyzed to describe the characteristics of the melanomas diagnosed and treated in this institution between 2006 and 2010. The fin dings of this study show very interesting patterns, which differ substantially from the patterns observed in the highincidence areas of the world. Although these are findings from one institution, which may represent a selective group of patients, they represent a large group of patients from an important hospital in terms of melanoma patients (115 patients treated annually). Assuming that these patterns represent the general pattern of melanomas diagnosed at a national level, it provides possible explanations for the relatively high case-fatality rate of melanomas in the country: many relatively aggressive subtypes and more than 50% of patients presenting advanced stage melanomas at diagnosis.
Whereas acral melanomas are very rarely diagnosed in Caucasian populations, they represent around 45% of all melanomas diagnosed at the INC. This is not a new finding; it is well known that acral melanomas are more frequent in non-Caucasian populations, particularly so for Asians. However, relative frequencies have very rarely been described, and even less for the South American continent. Acral melanomas constitute a very interesting, but understudied, subtype of melanomas, probably because of their rare frequency in high-incidence countries. The risk factors for acral melanomas are unknown, they are thought to be unrelated to ultraviolet radiation, unlike other melanoma subtypes.
Probably because of the high proportion of acral melanomas, the prevailing body sites at which melanomas occur also differ greatly from those observed in high-incidence countries. Whereas the great majority of melanomas in high-incidence geographical areas are mainly found on the trunk and arms of men and trunk and legs of women, in this series of patients the predominant localizations were the head, neck and feet in both genders.
The findings of this publication adds important information to the profile on the melanoma epidemiology in Latin America and form a good base from which to illustrate the need for further investigations into risk factors and prevention possibilities, prognosis and treatment options. It particularly highlights the high frequency of acral lentiginous melanomas in this part of the world, which is interesting information for those investigating biological pathways and possibilities for new treatment of this particular subtype of melanoma. The finding of a very large proportion of late diagnoses illustrates the need for better public awareness of the need to consult a physician when there are suspicious, changing lesions on the skin. Primary and secondary prevention messages should probably be adapted to the different ‘melanoma reality’ in this part of the world, with different presentation of melanomas, different body sites and most likely very different risk factors.
