Appendix Figure 1.Kaplan-Meier plots for patients with Merkel cell carcinoma treated with or without radiation therapy (RT) demonstrating (a) disease free survival, (b) overall survival, and (c) disease specific survival among all patients (n=171).

Appendix Table 1.Patient, tumor and treatment characteristics for patients with Merkel cell carcinoma treated with and withoutpostoperativeradiation (n=171).

Characteristics / All Patients / Radiation / No Radiation
% (n) / % (n) / % (n) / p-value
Median Age (years, range) / 74 (31-96) / 74 (31-96) / 76 (51-91) / 0.16
Sex / Male / 124 (72.5) / 96 (73.8) / 28 (68.3) / 0.49
Female / 47 (27.5) / 34 (26.2) / 13 (31.7)
Location / Head and Neck / 71 (41.5) / 58 (44.6) / 13 (31.7) / 0.17
Trunk / 18 (10.5) / 14 (10.8) / 4 (9.8)
Upper extremity / 51 (29.8) / 39 (30.0) / 12 (29.3)
Lower Extremity / 31 (18.1) / 19 (14.6) / 12(29.3)
Immunosuppression / No / 154 (90.1) / 118 (90.8) / 36 (87.8) / 0.58
Yes / 17 (9.9) / 12 (9.2) / 5 (12.2)
Median Tumor Size (cm, range) / 1.5 (0.2-8.0) / 1.5 (0.3-8.0) / 1.2 (0.2-5.0) / 0.28
Tumor Size (cm) / ≤2 / 72 (42.1) / 55 (42.3) / 17 (41.5) / 0.74
>2 / 31 (18.1) / 25 (19.2) / 6 (14.6)
Unknown / 68 (39.8) / 50 (38.5) / 18 (43.9)
Nodal Stage / Pathologic N0 / 101 (59.1) / 73 (56.2) / 28 (68.3) / 0.33
Pathologic N1 / 53 (31.0) / 44 (33.8) / 9 (22.0)
Clinical N1 / 17 (9.9) / 13 (10.0) / 4 (9.8)
Median Lymph Nodes Involved (#, range) / 2 (1-20) / 2 (1-20) / 2 (1-18) / 0.59
Extranodal Extension Present / No / 31 (41.9) / 29 (47.5) / 2 (15.4) / 0.06
Yes / 28 (37.8) / 22 (36.1) / 6 (46.2)
Unknown / 15 (20.3) / 10 (16.4) / 5 (38.5)
Median Depth of Invasion (mm, range) / 4.8 (0.3-45.0) / 5.1 (0.3-45.0) / 3.5 (0.8-12.4) / 0.06
Depth of Invasion (mm) / ≤1 / 7 (4.1) / 5 (43.8 / 2 (4.9) / 0.28
1.01-2.0 / 19 (11.1) / 15 (11.5) / 4 (9.8)
2.01-4.0 / 24 (14.0) / 16 (12.3) / 8 (19.5)
>4.0 / 69 (40.4) / 58 (44.6) / 11 (26.8)
Unknown / 52 (30.4) / 36 (27.7) / 16 (39.0)
Surgery of Primary / Excision / 168 (98.2) / 128 (98.5) / 40 (97.6) / 0.70
None (biopsy only) / 3 (1.8) / 2 (1.5) / 1 (2.4)
Resection margins of primary / Negative / 151 (88.3) / 114 (87.7) / 37 (90.2) / 0.26
Positive / 16 (9.4) / 14 (10.8) / 2 (4.9)
Lymphovascular Invasion / No / 7 (26.9) / 4 (21.1) / 3 (42.9) / 0.27
Yes / 19 (73.1) / 15 (78.9) / 4 (57.1)
Chemotherapy / No / 143 (15.4) / 106 (82.2) / 37 (92.5) / 0.11
Yes / 26 (15.4) / 23 (17.8) / 3 (7.5)

Appendix Table 2.Variables associated with disease free survival, overall survival and disease specific survival among all patients with Merkel cell carcinoma.

Variable / Disease Free Survival
Cox UV Analysis / Cox MV Analysis
KM 3-yr / HR (95% CI) / p-value / HR (95% CI) / p-value
Age / 1.05 (1.02-1.08) / <0.001 / 1.04 (1.25-2.48) / 0.002
Sex / Male / 57.1
Female / 83.9 / 0.53 (0.31-0.89) / 0.02 / 0.49 (0.29-0.84) / 0.01
Nodal Stage / Pathologic N0 / 74.0
Pathologic N1 / 51.6 / 1.67 (1.07-2.60) / 0.02 / 1.75 (1.10-2.78) / 0.02
Clinical N1 / 47.1 / 2.11 (1.11-4.01) / 0.02 / 2.74 (1.41-5.33) / 0.003
Radiation / No / 45.6
Yes / 70.1 / 0.50 (0.32-0.79) / 0.003 / 0.42 (0.26-0.70) / 0.001
Variable / Overall Survival
Age / 1.06 (1.03-1.10) / <0.001 / 1.06 (1.03-1.09) / 0.001
Sex / Male / 70.0
Female / 89.3 / 0.67 (0.38-1.18) / 0.16 / 0.60 (0.34-1.06) / 0.08
Nodal Stage / Pathologic N0 / 82.0
Pathologic N1 / 70.8 / 1.72 (1.11-2.66) / 0.02 / 1.39 (0.83-2.34) / 0.21
Clinical N1 / 47.1 / 2.18 (1.32-3.58) / 0.002 / 2.66 (1.38-5.16) / 0.004
Radiation / No / 59.6
Yes / 79.4 / 0.57 (0.34-0.95) / 0.03 / 0.53 (0.31-0.93) / 0.03
Variable / Disease Specific Survival
Sex / Male / 76.8
Female / 94.7 / 0.19 (0.05-0.79) / 0.02 / 0.19 (0.04-0.80) / 0.08
Nodal Stage / Pathologic N0 / 88.0
Pathologic N1 / 79.1 / 2.13 (0.89-5.12) / 0.09 / 2.15 (0.88-5.23) / 0.09
Clinical N1 / 50.0 / 6.83 (2.77-16.86) / <0.001 / 8.51 (3.31-21.86) / <0.001
Radiation / No / 70.9
Yes / 84.1 / 0.62 (0.28-1.36) / 0.23 / 0.39 (0.17-0.90) / 0.03
Abbreviations: CI, confidence interval; HR, hazard ratio; KM, Kaplan Meier, MV, multivariate. Variables non-significant values (p>0.05) are not shown.