Risk-factors for actinic keratosis 12-month turnover

Clinical factors associated with actinic keratosis turnover in organ transplant recipients include age, parents’ country of origin, hair color, skin cancer history and recent actinic keratosis treatment, according to a recent Australian study.

Previous studies have shown that these highly dynamic lesions often regress, then, recur. It is estimated that about 70 percent of squamous cell carcinomas develop from actinic keratoses. In the general population, increasing age, male gender, European ancestry, high cumulative sun exposure and baldness stand out as actinic keratosis risk factors.

Among organ transplant recipients, actinic keratosis prevalence rises with the duration of immunosuppressant medications. Researchers of this paper found in a previous study that actinic keratosis variability in a 12-month period is linked with an increased squamous cell carcinoma risk among organ transplant recipients. Despite a demonstrated association between actinic keratosis incidence, net gain and squamous cell carcinoma development, there are few studies looking at risk factors and their effects on actinic keratosis lesion incidence and regression rates.

To improve skin cancer surveillance in these patients, beyond counting actinic keratosis lesions, researchers studied risk factors that could impact 12-month actinic keratosis turnover in organ transplant recipients. It’s the first study, they write, to offer a detailed assessment using different risk factors to analyze the effect on the dynamics of actinic keratoses in organ transplant recipients.

They calculated numbers of incident actinic keratoses, regressed actinic keratoses and net change in actinic keratosis counts in a study of 150 renal and 89 liver organ transplant recipients. Subjects’ average age was 54 years and average time since transplantation was 11 years.

A physician performed baseline skin exams recording actinic keratoses and suspicious lesions at the study’s start, as well as 11 to 13 months later. Researchers recorded eye, skin and natural hair color and participants completed a health and sun survey questionnaire at baseline.

Researchers found big differences in actinic keratosis turnover. The number of incident and regressed actinic keratoses in a single organ transplant recipient ranged from zero to 229 in the study period. At the study’s start, actinic keratosis counts ranged from zero to 466.

They identified risk factors affecting the variation, but also found that actinic keratosis count at baseline matters, with significant associations being more likely when adults had less than 10 baseline actinic keratoses, compared to those with 10 or more.

“This study is novel in identifying associations with [actinic keratosis] variability, as opposed to [actinic keratosis] prevalence, which can be used to closely monitor [organ transplant recipients] at increased risk,” the authors write.

Not surprisingly, light hair color and older age were significantly associated with increased overall actinic keratosis change. Having two parents of Australian origin also signaled a greater likelihood of actinic keratosis change.

But having a skin cancer history before or after the transplant was associated with a lower actinic keratosis count turnover, overall, in adults with fewer than 10 actinic keratoses. Actinic keratosis regression was less likely, however, in those with a pre-transplant skin cancer history.

Sun exposure’s association was significant only in those with 10 or more baseline actinic keratoses, as subjects who spent more time in the sun on a given weekday had lower regression rates than those who were rarely sun exposed. Sun protection practices didn’t yield an association of significance in actinic keratosis variability.

The authors point out that subjects with 10 or more actinic keratoses at baseline and recently treated for actinic keratoses with topical therapy cryotherapy had a higher incidence of overall lesion change and lower actinic keratosis regression than those with lower lesion counts at the study’s start.

To better modify associated risk factors and, ultimately, reduce squamous cell carcinoma risk, researchers need to delve more into understanding the dynamics actinic keratoses, they write.

Limitations of the study include its size and that it is limited to organ transplant recipients, bringing into question whether the results would apply to an immunocompetent population.

REFERENCES

Jiyad Z, Marquart L, O'Rourke P, Green AC. “Incidence and Regression of Actinic Keratoses in Organ Transplant Recipients,” Acta Dermatology-Venereology. January 2017. DOI: 10.2340/00015555-2783.