The prognostic significance of sentinel node tumour burden in melanoma patients: an international, multicenter study of 1539 sentinel node-positive melanoma patients.
BACKGROUND
Sentinel node (SN) biopsy (SNB) and completion lymph node dissection (CLND) when SN-positive have become standard of care in most cancer centres for melanoma. Various SN tumour burden parameters are assessed to determine the heterogeneity of SN-positivity. The aim of the present study was to validate the prognostic significance of various SN tumour burden micromorphometric features and classification schemes in a large cohort of SN-positive melanoma patients.


METHODS
In 1539 SN-positive patients treated between 1993 and 2008 at 11 melanoma treatment centres in Europe and Australia, indices of SN tumour burden (intranodal location, tumour penetrative depth (TPD) and maximum size of SN tumour deposits) were evaluated.


RESULTS
Non-subcapsular location, increasing TPD and increasing maximum size were all predictive factors for non-SN (NSN) status and were independently associated with poorer melanoma-specific survival (MSS). Patients with subcapsular micrometastases <0.1mm in maximum dimension had the lowest frequency of NSN metastasis (5.5%). Despite differences in SN biopsy protocols and clinicopathologic features of the patient cohorts (between centres), most SN parameters remained predictive in individual centre populations. Maximum SN tumour size>1mm was the most reliable and consistent parameter independently associated with higher non-SN-positivity, poorer disease-free survival (DFS) and poorer MSS.


CONCLUSIONS
In this large retrospective, multicenter cohort study, several parameters of SN tumour burden including intranodal location, TPD and maximum size provided prognostic information, but their prognostic significance varied considerably between the different centres. This could be due to sample size limitations or to differences in SN detection, removal and examination techniques.
Erasmus University Medical Center, Daniel den Hoed Cancer Center, Rotterdam, The Netherlands.
Augustinus P T
AP
van der Ploeg
Erasmus University Medical Center, Daniel den Hoed Cancer Center, Rotterdam, The Netherlands.
Alexander C J
AC
van Akkooi
Melanoma Institute Australia, Sydney, Australia.
Lauren E
LE
Haydu
Melanoma Institute Australia, Sydney, Australia.
Richard A
RA
Scolyer
Memorial Sloan Kettering Cancer Center, New York City, NY, USA.
Rajmohan
R
Murali
Erasmus University Medical Center, Daniel den Hoed Cancer Center, Rotterdam, The Netherlands.
Cornelis
C
Verhoef
Melanoma Institute Australia, Sydney, Australia.
John F
JF
Thompson
Institut de Cancerologie Gustav Roussy, Villejuif, Paris-Sud, France. Electronic address: alexander.eggermont@igr.fr.
Alexander M M
AM
Eggermont
D015331:Cohort Studies; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008297:Male; D008545:Melanoma / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D016019:Survival Analysis; D047368:Tumor Burden
Melanoma; Pathology and survival; Sentinel node biopsy