ALBUQUERQUE – Adding topical tazarotene did not improve response to 5% imiquimod in lentigo maligna, based on data from nearly 300 patients.
But patients with higher levels of inflammation in response to topical therapy had significantly smaller surgical defects, required fewer surgical stages, and had improved clearance rates, said Nicholas Blickenstaff, a third-year medical student at the University of Utah and a former researcher at the Huntsman Cancer Institute, both in Salt Lake City.
Surgical excision with negative margins is the standard treatment for lentigo maligna, but the cancer’s predilection for the head and neck can cause disfigurement, especially with large tumors. Patients sometimes elect nonsurgical treatment because of cosmetic concerns, comorbidities, or both, Mr. Blickenstaff said at the annual meeting of the Society for Investigative Dermatology.
A prior study found that adding the topical retinoid tazarotene to 5% imiquimod showed a trend toward improved clearance in lentigo maligna, but the association did not reach statistical significance (Arch. Dermatol. 2012;148:592-6).
Based on those data, "we looked at a larger treatment cohort to determine if adding tazarotene to topical imiquimod increased clearance rates of lentigo maligna, as defined by the presence or absence of residual tumor at the time of surgical removal," said Mr. Blickenstaff.
He and his associates at the Huntsman Cancer Institute and the University of Utah School of Medicine conducted a retrospective chart study of 282 patients with an average age of 68 years and biopsy-confirmed lentigo maligna.
A total of 188 patients with 194 lesions received imiquimod 5% cream 5 days a week for 1-3 months, depending on the amount of inflammation observed, said Mr. Blickenstaff. Another group of 94 patients with 98 lesions received the same treatment plus tazarotene 0.1% gel twice weekly. Patients then underwent conservative staged excisions using Melan-A immunostaining on frozen sections to confirm negative margins. The investigators followed patients for an average of 43 months.
Using chart data, the investigators graded patients’ inflammatory responses to topical therapy on a 0-3 scale, with 0 interpreted as no erythema, 1 as mild erythema, 2 as moderate erythema, and 3 as severe erythema with possible surface erosions, said Mr. Blickenstaff.
The researchers found no difference between the two topical regimens in terms of presurgical clearance (P = 0.97). However, patients with higher levels of inflammation (scores of 2 or 3) were significantly more likely to be free of tumor at surgery than were other patients (odds ratio, 2.8; P = 0.002). Patients with more inflammation also had decreased postsurgical defect sizes (P = 0.023), and needed fewer stages to achieve clear margins (P = 0.015), Mr. Blickenstaff and his associates reported.
Patients required an average of 1.5 stages and a maximum of five stages to achieve clearance, Mr. Blickenstaff added. A total of four patients (1.4%) had a recurrence of lentigo maligna, and there were no deaths related to treatment or lentigo maligna, he said.
Based on the findings, "studies should evaluate whether the quality of the inflammatory response with 5% imiquimod is unique and required for efficacy," said Mr. Blickenstaff.
He is now a research fellow at UCSF Medical Center in San Francisco. He reported no conflicts of interest. The Huntsman Cancer Institute funded the study.