Managing dermatologic changes of targeted cancer therapy

How common a problem? The incidence of EGFR inhibitor (EGFRI)–related rash is noteworthy: Overall incidence ranges from 45% to 100% of treated patients, with 10% experiencing Grade 3 to 4 changes (covering > 30% of body surface, restricting activities of daily living, severe itching).⁹ Monoclonal antibody therapies that target EGFR, such as cetuximab, have a reported 90% risk of skin rash, with 10% also being of Grade 3 to 4.¹⁰ Risk factors for rash include skin phototype, male gender, and younger age.^11,12 Common cancer therapies with known skin effects are listed in the TABLE.¹³

What should you look for? The most common clinical manifestation of dermatologic toxicity is an acneiform, or papulopustular, rash marked by eruptions characterized as “acne-like” pustules with monotonous lesion morphology (Figure 1a). A hallmark of these lesions that can be used to help distinguish them from acne vulgaris is the absence of comedones on eruptions.

The timeline of the rash has been well characterized and is another tool that you can use to guide management:

1. During Week 1 of cancer treatment, the patient often experiences sensory disturbances, with erythema and edema.¹⁴
2. Throughout Weeks 2 and 3, erythematous skin evolves into papulopustular eruptions.
3. By Week 4, eruptions typically crust over and leave persistently dry skin for weeks.^15,16

Of note, the rash is dosage related; we recommend scrupulous vigilance when a patient is receiving a high dosage of a targeted therapy agent.

Controlling a rash

Treatment of EGFRI-associated skin changes stems from recommendations from a number of individual investigators and studies; however, few consensus guidelines exist to guide practice. Understanding of the underlying pathophysiological mechanism of skin changes has evolved, but preventive and treatment modalities remain unchanged—and limited.

Continue to: Always counsel patients...