Effectiveness and Prognosis of Systemic Chemotherapy for Unresectable Malignant Apocrine and Eccrine Tumors: A Real-World Multicenter Retrospective Study.

Abstract

Purpose: Malignant apocrine and eccrine tumors (MAETs) are extremely rare cutaneous adnexal malignancies, accounting for only 0.005%-0.01% of all skin tumors. These tumors are highly metastatic, and evidence regarding optimal chemotherapy and prognostic outcomes remains limited. This study aimed to evaluate the efficacy of systemic chemotherapy and overall prognosis in Japanese patients with unresectable MAETs.

Patients and methods: We conducted a retrospective, multicenter study involving 81 patients with unresectable MAETs treated at 27 institutions across Japan. Patients received one of three primary chemotherapy regimens: platinum-based (cisplatin or carboplatin), taxane-based (docetaxel or paclitaxel), or TS-1 (tegafur/gimeracil/oteracil). Patient demographics, objective response rates (ORRs), overall survival (OS), and progression-free survival were assessed. Survival curves were estimated using the Kaplan-Meier method.

Results: The estimated ORRs for the platinum-based, taxane-based, and TS-1 groups were 37.0%, 25.0%, and 22.2%, respectively, with no statistically significant differences among them (P = .527). The median OS and 5-year OS rate for the entire cohort were 29.0 months and 34.0%, respectively. The median OS and 5-year OS rates by regimen were as follows: platinum-based, 29.0 months and 36.2%; taxane-based, 22.0 months and 39.7%; and TS-1, 30.0 months and 13.9%, with no significant differences observed (P = .907). In addition, there were no significant differences in ORR or OS between patients receiving combined chemoradiotherapy and those receiving chemotherapy alone.

Conclusion: No single chemotherapeutic regimen demonstrated superior efficacy in patients with unresectable MAETs. These findings highlight the need for further investigations using larger, prospective cohorts and multidisciplinary approaches to establish optimal therapeutic strategies for this rare malignancy.