Bcc differs from Scc in that many lesions arise often in non sun exposed areas. It does not correlate as well with total sun exposure as Scc and solar keratoses.These authors point out that the frequency of Bcc on the trunk does correlate with excessive sun exposure. They looked at the different frequency of these superficial variants on the head and neck and the trunk.
Journal of the American Academy of Dermatology
Volume 56, Issue 3 , March 2007, Pages 380-386
Basal cell carcinoma on the trunk is associated with excessive sun exposure
Rachel E. Neale PhDa, Marcia Davis MPHb, Nirmala Pandeya MMedScib, David C. Whiteman PhDb and Adele C. Green PhDb
aFrom the Queensland Cancer Fund
bQueensland Institute of Medical Research
Accepted 20 August 2006. Spring Hill, Queensland, Australia. Available online 13 October 2006.
Background and Objective
Basal cell carcinoma (BCC) is the most common of all cancers. Ultraviolet radiation is the major etiologic agent in the pathogenesis of BCC, but there is not a straightforward relationship between cumulative exposure and risk. A high proportion of lesions arise on the trunk, which is generally much less exposed to the sun than the head, the major site affected. We tested the hypothesis that the phenotypic determinants and patterns of sun exposure that give rise to BCC on the head and trunk vary in a way that explains the anomalous site distribution.
Methods
The study was set in the context of the Nambour Skin Cancer Study, a community-based follow-up study among 1621 participants with virtually complete ascertainment of BCCs between 1992 and 2004. We compared phenotypic and sun exposure characteristics of participants who developed a first BCC of the head or trunk with those of participants who had no diagnosis of BCC.
Results
BCCs of the trunk were more likely to occur in men; they also occurred at a younger age than BCCs of the head. There was a positive association between sun sensitivity and BCC of the head that was absent for BCC of the trunk. A high number of solar keratoses conferred a greater than 3-fold risk for BCCs of both the head and the trunk. BCCs of the trunk had a particularly strong association with the number of reported sunburns and solar lentigines on the trunk, whereas many lentigines conferred a greater than 3-fold risk of truncal BCC compared with a 50% increased risk of BCC of the head.
Limitations
The relatively small numbers of tumors may have limited our ability to detect statistically significant differences.
Conclusions
BCCs of the trunk are the result of overexposure of the sensitive basal cells of the epidermis to ultraviolet radiation. This may result from acute intense exposures sufficient to cause sunburn among people whose ability to tan makes the skin of their face generally less susceptible to the carcinogenic effects of ultraviolet radiation.
3 comments:
THe foreign literature seems to me to emphasise that Bccs on the trunk are relatively less common. That is certainly not my experience and I suspect that of others in Oz. The prototypical patient is the 50+ year old deeply sun tanned "brickie" who you can pick as they walk through the door as likely to have several superficial or nodular Bccs on the back and trunk (as well as the others!). The lack of statistical data, especially from the primary care setting, makes it difficult to de definitive. Cliff's project is going to go a long way towards at least starting to answer some of these questions and bring up others. Morphoeic Bcc, I feel, occurs virtually exclusively on the head and neck so there may well be different aetiological patterns of sun exposure for differing types of Bcc as suggested in this article.
I would concur with your comments on morphoeic Bcc. Vitually always on the head and neck. We see multi[le superficial Bccs in the surfers , certainly most commonly on the back. I am not aware of gene differences between the different morphological types.
Totally agree Martin, I also do not see a preponderance of facial BCCs.
For what it's worth, I did an audit last year of a few month's procedures, and it came out like this for BCCs:
Total 458
Limbs 201
Torso 168
Scalp 5
Ear/Nose 41
Other face 43
There were only 37 aggressive (not superficial or solid) BCCs, 18 on nose/ear, 6 on the rest of the face.
Might I suggest that sun exposure pattern of hands and forearms is probably not all that different to that of the face, yet aggressive BCCs are rarely seen on the hands.
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