Abstract
Aim: In melanoma patients, we define incomplete sentinel node biopsy(I-SNB) as when fewer lymph nodes(LNs) are removed during sentinel node biopsy(SNB) than identified on the preoperative lymphoscintigram(LSG). This study quantifies the frequency of I-SNB and aims to evaluate any correlation with worse patient outcomes.
Materials and methods: Analysis of a retrospective case series of 2525 consecutive patients who had LSG and SNB for cutaneous melanoma at the Melanoma Institute Australia(MIA) from January 1996 until December 2006 with follow up until January 2011. Patients with multiple primary melanomas or that had SNB for recurrent melanoma were excluded(n=518). Information was retrieved from the MIA database, with LSG information from the separate database held at a nuclear medicine practice. All statistical analyses were performed using Microsoft Excel and SPSS 19.0.
Experience: Mean follow up was 54.9 months after SNB, with 103 patients lost to follow up. Sporadic missing data in the MIA database accounted for less than 5% for any characteristic.
Results: I-SNB occurred in 20% of total cases in the cohort(n=2007). For axillary patients(n=895), groin patients(n=569) and neck/axial patients(n=334); I-SNB occurred in 12%, 26% and 28% of cases respectively. There was a significant association between completeness of SNB and field of SNB(p<0.001). On univariate analysis, there was a significant relationship between I-SNB and worse disease-free survival(DFS, p=0.007, Figure1) with a trend towards worse melanoma-specific survival(MSS, p=0.056). However, I-SNB did not significantly influence regional recurrence-free survival(RRFS, p=0.144). There was no statistically significant relationship between I-SNB and worse DFS, RRFS or MSS on multivariate analysis. Significant univariate analysis differences on DFS(p=0.009, Figure2) and RRFS(p=0.039) were seen with sentinel node location(axilla better than groin and neck/axial). Significantly worse outcomes on MSS, DFS and RRFS were seen with male gender, increasing age, high mitotic count, ulceration, and increasing Breslow thickness.
Conclusion: This study demonstrates no statistically significant relationship between I-SNB and patient outcomes when adjusting for known prognostic factors. The significant relationship(DFS) and consistent trend(MSS) in univariate analysis does not exclude the possibility that I-SNB may have a weak relationship with worse outcomes. Factors such as variable rates of I-SNB in different LN fields (relates to surgical skill and anatomical accessibility) and different distribution of the number of sentinel nodes in different nodal fields may confound the analysis.
Figure1
Figure2