In an analysis of National Cancer Data Base data reported in the Journal of the National Cancer Institute, Shailender Bhatia, MD, of the University of Washington/Fred Hutchinson Cancer Research Center, and colleagues found that adjuvant radiotherapy was associated with a survival benefit in patients with stage I and II but not stage III Merkel cell carcinoma, with no benefit of adjuvant chemotherapy being identified.
The retrospective analysis included 6,908 patients who had stage I to III disease and had received surgery, surgery and radiotherapy, or radiotherapy as the primary treatment modality. All patients were diagnosed between January 1996 and December 2008. Multivariate analysis for overall survival adjusted for prognostic variables including age, sex, comorbidities, margin status, primary tumor site and size, and lymph node status.
Benefit of Radiotherapy in Localized Disease
On multivariate analysis, use of adjuvant radiotherapy was associated with improved overall survival among 3,369 patients with stage I disease (hazard ratio [HR] = 0.71, P < .001) and among 1,474 with stage II disease (HR = 0.77, P < .001) but not among 2,065 patients with regional nodal metastases (stage III; HR = 0.98, P = .80) vs surgery alone. Adjuvant chemotherapy was not associated with a significant benefit in stage I (HR = 0.79, P = .11), stage II (HR = 1.14, P = .30), or stage III disease (HR = 0.97, P = .71) vs no chemotherapy.
The investigators concluded: “In this study of the largest [Merkel cell carcinoma] cohort reported to date, adjuvant [radiotherapy] was associated with improved [overall survival] in stages I-II [Merkel cell carcinoma]. Neither adjuvant [radiotherapy] nor chemotherapy was associated with improved [overall survival] in stage III [Merkel cell carcinoma]. These results, with the limitations of retrospective analyses, are consistent with earlier studies suggesting benefit with adjuvant [radiotherapy] but do not support the routine use of adjuvant chemotherapy in [Merkel cell carcinoma].”
The study was supported by National Center for Advancing Translational Sciences grants from the National Institutes of Health, Michael Piepkorn endowment, and Merkel patient gift funds.