Advanced Scrotal Extramammary Paget's Disease Treated With Apatinib: A Case Report

Extramammary Paget Disease: a Therapeutic Challenge, for a Rare Entity

PURPOSE OF REVIEW

Extramammary Paget disease (EMPD) is a rare entity which is more frequently localized at the vulva, though it only accounts for 1-2% of vulvar neoplasms. It is a primary cutaneous adenocarcinoma whose cell of origin is still a matter of controversy: it can either arise from apocrine/eccrine glands or from stem cells. The diagnosis demands a biopsy and entails a histopathological analysis by which cells show similar characteristics as breast Paget disease.

RECENT FINDINGS

Treatment approach can entail surgery, radiotherapy, photodynamic therapy, systemic chemotherapy, and topical chemotherapy. For metastatic disease, many different chemotherapy regimens have been explored and even targeted therapy can play an important role in this disease. Since almost 30-40% of patients overexpress HER-2, trastuzumab and anti-HER-2 therapies can be employed in this setting. Due to its low incidence, there is almost no specific evidence on therapeutic interventions for this disease. Thus, there is a neat unmet need for molecular characterization of EMPD and diagnostic tools that allow clinicians to guide treatment both in the early and in the advanced disease settings. In this review, we aim to summarize available evidence about diagnosis and treatment of EMPD, both localized and metastatic, and to provide a comprehensive analysis that may help clinicians for therapeutic decisions.

Treatment outcomes of advanced/metastatic extramammary Paget's disease in Korean patients: KCSG-RC20-06

BACKGROUND

Extramammary Paget's disease (EMPD) is rare. There are no standard treatments due to its rarity and few clinical trials.

METHODS

The objective of this multicenter study was to investigate treatment outcomes of Korean patients with advanced/metastatic EMPD. Data were collected retrospectively from 14 institutions participating in Korean Cancer Study Group (KCSG) Rare Cancer Committee.

RESULTS

A total of 37 patients were identified. Of these 37 patients, 6 received locoregional therapy as a first-line treatment. In 31 patients who received systemic chemotherapy as a first-line treatment, platinum-based chemotherapy (n = 22) achieved an objective response rate (ORR) of 45.5% and a median progression-free survival (PFS) of 7.89 months. Taxane-based chemotherapy (n = 8) achieved an objective response rate of 62.5% and median PFS of 9.73 months. In second-line chemotherapy, platinum-based chemotherapy (n = 4) had a disease control rate (DCR) of 75.0% and median PFS of 3.45 months. Taxane-based chemotherapy (n = 8) had a DCR of 75.0% and a median PFS of 8.67 months. Six patients received anti-human epidermal growth factor receptor 2 (HER2) antibody during first- and second-line chemotherapy. Overall, systemic chemotherapy combined with anti-HER2 antibody had an ORR of 100% and a median PFS of 13.31 months. The ORR and PFS with systemic chemotherapy combined with trastuzumab was better than platinum- and taxane-based chemotherapy only.

CONCLUSIONS

Due to its rarity, advanced or metastatic EMPD still has no established standard treatment. Results of our study indicate that the combination of trastuzumab with taxane has longer survival than trastuzumab monotherapy or conventional platinum- or taxane-based chemotherapy.

Current Management and Treatment of Extramammary Paget's Disease

OPINION STATEMENT

Extramammary Paget's disease (EMPD) is a rare neoplastic disease affecting areas rich in apocrine glands in the elderly. EMPD clinically resembles a benign inflammatory skin disease, and ill-defined tumor borders can lead to misdiagnosis and incomplete excision. Several prognostic factors have been reported, including nodule formation, tumor thickness, tumor invasion, lymphovascular invasion, and a perianal location, which are characteristic of primary tumors. EMPD typically presents as an in situ tumor spreading horizontally within the epidermis and then invading into the dermis as it transitions to a vertical growth phase. For this reason, tumor thickness, rather than tumor size, is correlated with patient prognosis. The best treatment for resectable EMPD is complete surgical removal of the tumor. EMPD sometimes has unclear tumor borders, and it can unexpectedly spread beyond its clinical boundaries. Surgical resection in such cases is often associated with tumor-positive margins, which can result in recurrence. However, surgical excision with wide margins may deteriorate patients' organ functions and quality of life. Mohs micrographic surgery may be ideal for controlling the surgical margins and minimizing the sacrifice of normal tissue, but this technique is not always feasible because of constraints associated with the medical environment. No standard treatment for unresectable or metastatic EMPD has been established. Although conventional chemotherapy has been used as the first-line treatment, it frequently causes adverse events, and consequently, targeted therapy will become more valuable in the near future.

The Outcome of Chemotherapy for Metastatic Extramammary Paget's Disease

The efficacy and survival impact of conventional chemotherapies for metastatic extramammary Paget’s disease (EMPD) have not been fully elucidated. This study examined the long-term outcome of chemotherapy for this indication. We conducted a retrospective review of 21 patients with distant metastatic EMPD (14 patients treated with chemotherapy and 7 patients treated without chemotherapy). The response rate of chemotherapy and patient survival were statistically analyzed. Among the 14 patients treated with chemotherapy, 12, 1, and 1 patient received docetaxel, paclitaxel, and low-dose 5-fluorouracil plus cisplatin, respectively, as the first-line treatment. The response rate was 50.0% (7/14), and the disease control rate was 64.3% (9/14). The median progression-free survival (PFS) and overall survival (OS) were 16.8 and 27.9 months, respectively. Multivariate analyses revealed that chemotherapy was a significant factor for prolonged PFS (hazard ratio (HR) 0.22, p = 0.038) but not for OS (HR = 1.71, p = 0.54). Ten patients (71.4%) had severe (grade 3 or 4) hematological adverse events. Although conventional chemotherapy improved PFS, we failed to show a significantly improved OS. Considering the frequent adverse events of conventional chemotherapy, targeted therapy may become a mainstay for the treatment of metastatic EMPD.