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Karyometric analysis of actinic damage in unexposed and sun-exposed skin and in actinic keratoses in untreated individuals.

OBJECTIVE
To assess the ability of karyometric analysis to demonstrate progression of actinic damage as a function of sun exposure in individuals with actinic keratoses (AKs) and to evaluate the stability of that assessment over a 3-month period.


STUDY DESIGN
Biopsies from subjects with AKs were obtained from unexposed skin, sun-exposed skin and AK lesions. Subjects used an SPF 50 sunscreen, and 3 months later additional biopsies were taken from sun-exposed and AK sites. A total of 13,300 nuclei were recorded from 31 subjects.


RESULTS
Measures of nuclear abnormality (NA) and effects of sun damage based on discriminant function (DF) scores were derived. Actinic damage levels varied significantly across biopsy site, demonstrating the method's sensitivity. Accrual of actinic damage was demonstrated in sun-exposed skin and AK lesions when all nuclei were examined over 3 months but only for sun-exposed skin when the worst-damaged nuclei were examined. This suggests a ceiling effect of nuclear damage in the progression to abnormality. Within-subject variability was similar for both NA and DF when all nuclei were considered. Among the worst-damaged nuclei (as defined by high DF), DF showed lower within-case variability than NA, perhaps due to a reduction in nuclear heterogeneity.


CONCLUSION
Karyometry's ability to detect subtle levels of actinic damage in nuclear chromatin patterns may make it useful in screening agents for possible use in cancer chemoprevention.