title: Single-fraction radiation therapy in patients with metastatic Merkel cell carcinoma.
abstract: Merkel cell carcinoma (MCC) is an aggressive, polyomavirus-associated cancer with limited therapeutic options for metastatic disease. Cytotoxic chemotherapy is associated with high response rates, but responses are seldom durable and toxicity is considerable. Here, we report our experience with palliative single-fraction radiotherapy (SFRT) in patients with metastatic MCC. We conducted retrospective analyses of safety and efficacy outcomes in patients that received SFRT (8 Gy) to MCC metastases between 2010 and 2013. Twenty-six patients were treated with SFRT to 93 MCC tumors located in diverse sites that included skin, lymph nodes, and visceral organs. Objective responses were observed in 94% of the measurable irradiated tumors (86/92). Complete responses were observed in 45% of tumors (including bulky tumors up to 16 cm). "In field" lesion control was durable with no progression in 77% (69/89) of treated tumors during median follow-up of 277 days among 16 living patients. Clinically significant toxicity was seen in only two patients who had transient side effects. An exploratory analysis suggested a higher rate of in-field progression in patients with an immunosuppressive comorbidity or prior recent chemotherapy versus those without (30% and 9%, respectively; P = 0.03). Use of SFRT in palliating MCC patients was associated with an excellent in field control rate and durable responses at treated sites, and with minimal toxicity. SFRT may represent a convenient and appealing alternative to systemic chemotherapy for palliation, for which most patients with oligometastatic MCC are eligible. SFRT may also synergize with emerging systemic immune stimulants by lowering tumor burden and enhancing presentation of viral/tumor antigens.
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Jayasri G
authors.initials: JG
authors.lastname: Iyer
authors.affiliation: Department of Radiation Oncology, University of Washington, Seattle, Washington.
authors.forename: Upendra
authors.initials: U
authors.lastname: Parvathaneni
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, Washington.
authors.forename: Ted
authors.initials: T
authors.lastname: Gooley
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Miller
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, Washington.
authors.forename: Elan
authors.initials: E
authors.lastname: Markowitz
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Astrid
authors.initials: A
authors.lastname: Blom
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Lewis
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Ryan F
authors.initials: RF
authors.lastname: Doumani
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Parvathaneni
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Austin
authors.initials: A
authors.lastname: Anderson
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Amy
authors.initials: A
authors.lastname: Bestick
authors.affiliation: Department of Radiation Oncology, University of Washington, Seattle, Washington.
authors.forename: Jay
authors.initials: J
authors.lastname: Liao
authors.affiliation: Department of Radiation Oncology, University of Washington, Seattle, Washington.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Kane
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, Washington.|Seattle Cancer Care Alliance, Seattle, Washington.|Department of Medicine/Oncology, University of Washington, Seattle, Washington.
authors.forename: Shailender
authors.initials: S
authors.lastname: Bhatia
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.
authors.forename: Kelly
authors.initials: K
authors.lastname: Paulson
authors.affiliation: Department of Medicine/Dermatology, University of Washington, Seattle, Washington.|Fred Hutchinson Cancer Research Center, Seattle, Washington.|Seattle Cancer Care Alliance, Seattle, Washington.
authors.forename: Paul
authors.initials: P
authors.lastname: Nghiem
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000556:secondary; D015266:Carcinoma, Merkel Cell / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010166:Palliative Care / Q000379:methods; D011878:Radiotherapy / Q000009:adverse effects / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
keywords: Merkel cell carcinoma; Merkel cell polyomavirus; single-fraction radiation therapy; skin cancer