Abstract P3-08-38: Primary cutaneous melanoma of the breast in women. A retrospective study of 82 patients

Background: Primary cutaneous melanoma of the breast (PCMB) is a relatively uncommon type of melanoma staged according to the AJCC system for other cutaneous melanomas. However, whether their outcome is different from primary cutaneous melanomas of other sun-exposed sites and the features that predict outcome specifically in PCMB are currently unclear. Moreover, histologically, the breast skin is considered to be a special site for melanocytic lesions. Therefore, we analyzed a retrospective cohort of female PCMB patients to determine the clinical and primary tumor features that correlate with time-to-event outcomes of overall survival (OS) and disease specific survival (DSS). Design: We identified women with PCMB diagnosed and/or treated at our institution between 2002 and 2015. The following data were collected: clinical/ demographic features (age at diagnosis, ethnicity, anatomic site [nipple-areolar complex, upper, lower, medial, lateral]); primary tumor pathologic features (Breslow thickness, Clark level, ulceration, mitotic rate, vertical growth phase (VGP), regression, lymphovascular invasion (LVI), perineural invasion (PNI), tumor infiltrating lymphocytes (TIL) and cytology); and metastatic disease features (satellitosis, date and metastasis to sentinel and/or regional lymph nodes, clinical detectability of nodal metastasis, and date and site of distant metastases). Kaplan Meier methods, univariate and multivariate Cox proportional hazards regression models determined associations with OS and DSS. Results: 82 cases, including 16 in-situ and 66 invasive PCMBs were identified. Most patients were white (98%), with a median age at diagnosis of 40.5 years (range: 15-77). With a median follow up of 7.6 years, the 1, 3, 5, 10-year OS rates were 97.4%, 94.7%, 91.9% and 81.3%, respectively; the 1, 3, 5, 10-year DSS rates were 98.7%, 95.9%, 93.1% and 86.9%, respectively; the median OS and DSS were not reached. Thirteen patients developed metastasis: 5 regional only, 1 distant only and 7 both; of which 6 had metastatic disease at presentation. Eleven patients died, and 8 was due to progression of PCMB. Most of the invasive PCMB were of superficial spreading type (84.8%), with median tumor thickness of 0.47 mm. Univariate analysis of patients with invasive melanoma revealed the following features to be associated with shorter survival (Table 1): age at presentation, Breslow thickness, Clark level, ulceration, mitotic rate and VGP; while histologic type, anatomic site, LVI, PNI, regression, associated nevus, cytology, and TIL were not significant. Adjusting covariate of features significant in univariate analysis, the multivariate analysis demonstrated only Breslow thickness and ulceration to be independently associated with OS and DSS. Conclusion: Primary cutaneous melanomas of the breast often affects white adult women and increasing tumor thickness and ulceration are associated with shorter survival, similar to primary melanomas of other cutaneous sites. Citation Format: Madhuchhanda Roy, Junsheng Ma, Aysegul A Sahin, Senthilkumar Damodaran, Michael T Tetzlaff, Jonathan L Curry, Ana M Ciurea, Jing Ning, Carlos A Torres-Cabala, Doina Ivan, Phyu P Aung, Merrick I Ross, Jeffrey E Gershenwald, Michael A Davies, Victor G Prieto and Priyadharsini Nagarajan. Primary cutaneous melanoma of the breast in women. A retrospective study of 82 patients [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-08-38.