Table 1 Patient and treatment characteristics

Number of patients

24

Age at initial diagnosis

63.7 y (27.9 y -78.4 y)

Age at RT

67.4 y (29.3 y – 79.3 y)

Initial Breslow level

3 (1.1–15)

Initial clark stage

 3

1

 4

9

 Unknown

14

Stage at initial diagnosis

 1B

2

 2A

2

 2B

1

 2C

4

 3B

6

 3C

2

 4

4

 Unknown

3

Stage at RT

 3B

1

 3C

2

 4

19

 Unknown

2

Prior immunotherapy

11

 Interferon

4

 Nivolumab plus ipilimumab

4

 Nivolumab

3

Concomitant immunotherapy

8

 Nivolumab

5

 Pembrolizumab

2

 Nivolumab plus ipilimumab

1

RT series

27

Prior RT-series

6

Normofractionationed RT-series

16

 RT-dose

54 Gy (10.8 Gy-66.6 Gy)

 RT fractionation

1.8 Gy (1.8 Gy-2 Gy)

Hypofractioned/Stereotactic RT-series

11

 RT-dose

20 Gy (20 Gy-39 Gy)

 RT fractionation

10 Gy (3 Gy-20 Gy)

Toxicities

 Anemia

12 (11 Grade 1, 1 Grade 2)

 Thrombocytopenia

2 (Grade 1)

 Lymphopenia

16 (8 Grade 1, 8 Grade 2)

 Neutropenia

1 (Grade 3)

 Mucositis

1 (Grade 3)

 Erythema

8 (4 Grade 1, 2 Grade 2, 2 Grade 3)