1. BRAF mutation rates in primary and metastatic Cutaneous melanoms Bristol 2016+2017
Dr Yve Zhang (Consultant, Cellular Pathology)
Dr Jonathan Potts (Specialty Trainee, Cellular Pathology)
Dr Kanwal Sohail (Specialty Trainee, Cellular Pathology)
Claire Faulkner (Clinical Scientist, Genetics)

2. Aims
Determine the frequency of BRAF mutation in primary and metastatic melanomas in Bristol and compare with published studies
Compare methods of test material preparation to determine if they are comparable
Characterise the clinical and pathological characteristics of BRAF-mutated melanomas in Bristol

3. Background
Mutations in BRAF result in constitutional activation of the MAPK signaling pathway
The pathway regulates the transcription of numerous proteins that control cell division and differentiation
BRAF mutation is involved in many different malignancies
Also observed in naevi (70-80%)
In melanomas, most common BRAF mutation is V600E

4. BRAF mutation
BRAF-mutated metastatic melanomas treated with BRAF and MEK inhibitors show improved survival compared with standard chemotherapy
BRAF mutation frequency in melanomas vary in different studies, usually around 40-60%
Higher mutation rates associated with certain clinical and pathological characteristics – younger age group, superficial spreading subtype, non-sundamaged skin, non- mucosal melanoma, metastatic melanoma

5. methodology Patients from NBT and UHB
Primary and metastatic cutaneous melanomas tested at Bristol Genetics Laboratory in 2016 and 2017
Patients from NBT and UHB
Primary mucosal melanomas excluded
Paraffin curls or mounted slides
Melanoma dataset items from histopathology report

6. Curls vs slides

7. REsults 312 patients identified over 2 years Age range 31-99 years
Mean age 69 years, median age 71 years
64% male and 36% female

8. Age of cohort
Frequency
Age group

9. Curls vs slides – 2016 and 2017 PET sample Total BRAF mutated BRAF Wt
169 (54%)
63 (37%)
106 (63%)
Slide
142 (46%)
39 (27%)
103 (73%)
311
102 (33%)
209 (67%)
2016 – virtually identical (curls 36% vs slides 34%)
2017 – Curls 38% vs slides 18%

10. Braf mutation is not associated with gender
Total
BRAF Mutated
BRAF Wt
Male
199 (64%)
62 (31%)
137 (69%)
Female
113 (36%)
40 (35%)
73 (64%)
312
102 (33%)
210 (67%)

11. BRAF mutation is associated with age

12. Primary vs metastasis Tumour Total BRAF Mutated BRAF Wt Primary 152
45 (29.5%)
107 (70.5%)
Metastasis
164
56 (34%)
108 (66%)

13. Histological Subtypes
Total
BRAF Mutated
SSM 66
28 (42%) NM 60
11 (18%)
LMM 3
1 (33%)
Other 22
8 (36%)
Not specified 1
1 (100%)
Superficial spreading and nodular melanoma were the commonest subtype
Mutation rates were significantly higher in superficial spreading melanomas

14. BRAF mutation is not associated with Breslow thickness
Breslow Thickness (mm)
Total
BRAF Mutated 1
0 (0%) 14
5 (35%) 55
14 (25%)
>4.0 71
23 (32%)
Not specified 4

15. Braf mutation is not significantly affected by ulceration
Total
BRAF mutated %
Present
93 (63.5%) 23
24.5%
Absent
53 (36%) 21
39.50%
Not Specified 6 1
16.50%

16. V600e is the most common mutation
Types of BRAF Mutations
Total
Primary
Metastasis
p.Val600Glu 77
34 (44%)
43 (56%)
p.Val600Lys 19
9 (47%)
10 (52.5%)
Thr599dup 2 1
p.Val600Arg 3

17. Braf is frequently mutated in brain mets
Location of metastasis
Total
BRAF Mutated %
Lymph node 89 30
34%
Skin 11
36.5%
Soft tissue 1 9%
Lung 13 6
46%
Brain 9 7
78%
Other visceral organs
14%
Further analysis of data: 11/14 (79%) brain metastases harboured BRAF mutation

18. Important points
Our BRAF mutation rates are slightly lower than most published studies at 33%
This may be explained by the skew to older patients tested
Ulceration does not significantly affect mutation rate, in fact non-ulcerated melanomas showed slightly higher mutation rates
Almost twice as many men tested as women
Brain metastases have a high rate of BRAF mutation
BRAF mutations slightly more frequent in paraffin curls than slides

19. Further work Re-audit yearly
Assess trend for BRAF mutation in paraffin curls vs slides
If only a small amount of tumour was tested and was BRAF wild-type, consider repeating the test on a different tumour especially if young patient/SSMM.

20. Thanks Any questions