Age, preoperative size may predict subclinical spread of melanoma in situ

Source: Healio; Hematology-Oncology, April 2014

NEW YORK — A patient’s age and the preoperative size of lesions may help predict subclinical spread of melanoma in situ treated with Mohs’ micrographic surgery, according to study results presented at the HemOnc Today Melanoma and Cutaneous Malignancies meeting.

Patients with melanoma in situ who undergo conventional excision may have residual disease, increasing the likelihood of recurrence and the need for additional surgery. Mohs’ micrographic surgery (MMS) enables improved detection and excision of subclinical microscopic spread, reducing the likelihood of local recurrence and the need for additional surgery, according to background information provided by researchers.

In the current study, Tuzar M. Shin, MD, PhD, and colleagues from the department of dermatology at the Hospital of the University of Pennsylvania in Philadelphia, aimed to create a prediction model for subclinical spread of melanoma in situ by assessing the clinical and pathologic factors associated with the requirement for two or more stages of microscopic clearance by MMS.

Shin and colleagues retrospectively analyzed a cohort of patients with melanoma in situ treated at a single center between March 2006 and September 2013. All patients underwent MMS with MART-1 immunostaining.

Researchers identified 679 cases of melanoma in situ. The cohort included 404 men (60%) and 275 women (40%). The mean age of patients was 65 years (range, 18-98).

The majority of tumors (80%) were located on the head and neck, whereas 137 tumors (20%) were found on the trunk or extremities.

Results showed 462 tumors (68%) were cleared after one stage of MMS, and 217 (32%) required an additional stage of MMS.

Shin and colleagues observed a statistically significant association between several characteristics and the need for two or more stages of MMS. Those characteristics included age ?60 years (P=.025), recurrent status (P=.0001), preoperative area ?1 cm2 (P<.0001) and anatomic location on the head and neck (P=.0009).

Results of univariate analysis showed age, preoperative size, recurrent status and lesion location on the head and neck were associated with a higher likelihood of needing two or more stages of MMS to obtain tumor-free margins. More than half (53%) of patients with recurrent lesions required two or more MMS stages to obtain tumor-free margins compared with 28.5% of patients with primary lesions.

The likelihood of clearance after one stage of MMS was greater for lesions on the trunk or extremities than lesions on the head and neck (80.3% vs. 65.5%). Among lesions on the head and neck, sites with the lowest clearance rates after one stage of MMS were the eyelid (36.4%), nose (55.6%), forehead/brow (60%), scalp/mastoid (64.4%) and ear (68.5%).

“These data support current appropriate use criteria for Mohs’ surgery to treat melanoma in situ located on the head/neck or recurrent lesions,” Shin and colleagues wrote. “Age and preoperative size, variables which are not part of the current guidelines, may help predict subclinical spread. Our results suggest that Mohs’ surgery for melanoma in situ may be useful for older patients and larger lesions.”