Managing dermatologic changes of targeted cancer therapy

Does rash correlate with cancer treatment efficacy?

Despite troubling dermatologic effects of cancer therapies, a retrospective analysis of several clinical trials has revealed another side to this coin: namely, the appearance, and the severity, of a rash correlates positively with objective tumor response.¹⁴ That correlation allows the oncologist to use a rash as a surrogate marker of treatment efficacy²⁰ (although, notably, there remains a lack of prospective trials that would validate a rash as such a marker). Epidermal growth factor receptor-tyrosine kinase inhibitors are mainly prescribed in patients who harbor an activating EGFR mutation; no studies have stratified patients by EGFR mutation and incidence of rash.³³

The upshot? Although there are gaps in our understanding of the relationship between a rash and overall survival, we are nevertheless presented with this para­digm: A patient who is taking an EGFR-tyrosine kinase inhibitor and who develops a rash should be continued on that treatment for as long as can be tolerated, because the rash is presumed to be a sign that the patient is deriving the greatest clinical benefit from therapy.^14,20,33

CORRESPONDENCE
Kevin Zarrabi, MD, MSc, Department of Medicine, Health Science Center T16, Room 020, Stony Brook, NY 11790-8160; Kayvan.zarrabi@gmail.com

ACKNOWLEDGMENT
Ali John Zarrabi, MD, provided skillful editing of the manuscript of this article.