ORLANDO – Oral isotretinoin holds potential as a bridge therapy for cancer patients who develop severe rashes during treatment, according to Dr. Milan J. Anadkat.
Dermatologists can play an integral role here. "Most oncologists see these patients first, and most oncologists are not enrolled in the iPledge program," said Dr. Anadkat of the division of dermatology at Washington University in St. Louis.
He noted that all treatment options are off label because there are no Food and Drug Administration–approved agents to treat chemotherapy-related cutaneous toxicities.
Getting patients through rashes that occur within a week or two of beginning targeted chemotherapy is important, as patients who develop the greatest reactions tend to have cancers that respond best to treatment, said Dr. Anadkat at the annual meeting of the Florida Society of Dermatology and Dermatologic Surgery. For this reason, the management of these patients is more complicated than simple drug cessation.
"The problem with just taking them off the drug is that they have cancer. Ultimately, the big goal here is treating the cancer, not avoiding the rash," he said.
Tetracycline or doxycycline can also reduce the severity of the rash, but the timing of administration is important. Better outcomes are associated with prophylaxis that is timed with the initiation of EGFR (epidermal growth factor receptor) inhibitors (Cancer 2008;113:847-53). "Waiting for the rash to appear is not the time to give it. It makes a difference if you give at day 0, not in terms of incidence but in the severity of the rash," he said.
Educate patients that the rash typically appears in an estimated 60%-90% of people within 8-10 days of EGFR inhibitor initiation, with a peak presentation at 2-4 weeks. "Bridging them through with something as effective as isotretinoin is useful," said Dr. Anadkat.
The rash generally appears on the face and upper trunk, but be careful not to confuse the presentation with a photo-exposure phenomenon.
Although some oncologists will describe the skin eruptions as "acnelike," histology will show mixed inflammatory infiltrate and follicular rupture. For this reason, "topical acne medications do very little," Dr. Anadkat said. Also, rule out infection, except when patients present with pustules on their arms, legs, or other non–EGFR receptor areas.
EGFR inhibitors can cause inflammatory alopecia, eyelash trichomegaly, and periungual and nail alterations.
About one in six patients will develop periungual or nail abnormalities, typically on their first finger or toe. These effects can be painful, Dr. Anadkat said. Culture is mandatory to rule out superinfection.
Again, the approach is to get patients through the adverse events with petroleum jelly, high-dose topical steroids, or oral tetracyclines. "Tumor markers are going down; [oncologists] are not going to want to stop chemotherapy for a painful thumb or toe," he said. "I recommend antimicrobial soaks with bleach or vinegar to prevent paronychia superinfection."
Dry, itchy skin is another concern with long-term EGFR inhibitor treatment. Histology shows "stark differences" in the stratum corneum. "This is the No. 1 side effect for patients on long-term EGFR – 3 months or longer; [it is] not a grade 3 or higher toxicity, but it is annoying."
Investigators compared oral minocycline and topical tazarotene prophylaxis in a study of 48 patients with cetuximab associated rash (J. Clin. Oncol. 2007:25:5390-6). Although oral minocycline was associated with reduced lesion counts, topical tazarotene yielded no significant benefit. "Again, this is not acne," Dr. Anadkat said.
He disclosed being a consultant or speaker for AstraZeneca, Bristol-Myers Squibb, Eisai, Genentech, and ImClone regarding strategies for managing skin toxicities from chemotherapy. He has never prescribed chemotherapy agents.