Abstract
BackgroundExtrapulmonary small cell carcinomas (ESCC) are rare but aggressive tumors. Relapses are common despite treatment with chemotherapy and/or radiotherapy. Prospective data for treatment of ESCC are lacking; treatment of these cancers usually incorporates lung small cell carcinoma treatment recommendations. Cancer staging remains the most important prognostic factor. Cancer immunotherapy targeting the PD-1/PD-L1 pathway has shown efficacy in multiple tumor types, and could be an appealing treatment strategy for these rare tumors.MethodsWe investigated PD-L1 expression by immunochemistry (IHC) in ESCCs diagnosed at University of Massachusetts Medical Center, from 1999 to 2016. 34 cases with sufficient material were selected for PD-L1 IHC analysis using clone E1L3N. PD-L1 expression was evaluated using the combined positive score (CPS). Retrospective chart review was performed. We evaluated the incidence and prognostic value of PD-L1 expression in ESCC at our institution.ResultsTwelve out 34 cases (35%) had PD-L1 CPS scores ≥1. Ten cases had CPS scores ranging 1–5, whereas 2 cases had CPS scores > 80. The overall response rate to the standard chemotherapy with/without radiotherapy in the PD-L1 positive group was 80% versus 67% for the PDL-1 negative group (p-value 0.67). The median overall survival for the PD-L1 positive group, regardless of stage, was 11.5 months versus 7 months for PD-L1 negative group (p-value 0.34). Patients with limited stage disease with positive PD-L1 had a median survival of 53 months compared to 15 months for patients with PD-L1 negative limited stage (p-value 0.80).ConclusionsThis study showed that at least one third of our ESCC tissue samples expressed PD-L1. There was a trend for higher response rates to the standard chemotherapy with/without radiotherapy and improved survival in PD-L1 positive patients. Further studies are required to understand the implications of immune dysregulation in these aggressive tumors. PD-L1/PD-1 inhibitors should be investigated in this group of patients.
Highlights
Extrapulmonary small cell carcinomas (ESCC) are rare but aggressive tumors
We investigated PD-L1 expression by immunochemistry (IHC) in ESCC diagnosed at University of Massachusetts Medical Center between 1999 and 2016
While disease staging and the site of origin of ESCC remain the most important prognostic factors, these results suggest that PD-L1 expression could be a predictive variable for prognosis and response to chemotherapy in ESCC
Summary
Extrapulmonary small cell carcinomas (ESCC) are rare but aggressive tumors. Cancer staging remains the most important prognostic factor. Extrapulmonary small cell carcinomas (ESCC) have an aggressive nature characterized by early, widespread metastases. These cancers are rare with a reported incidence of 0.1 to 0.4% in North America and represent up to 5% of all cases of small cell carcinoma [1]. The median survival for limited and extensive disease ranges from 1.4 to 3.5 years and 8 to 12 months, respectively. Either limited or extensive, remains the most important prognostic factor for these cancers [3]. The most commonly reported primary sites of disease are the gastrointestinal tract, genitourinary system, and ESCC of unknown primary tumor [3, 4]
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