Several authors have, by creating nomograms and scoring systems, attempted to define a subset of SLN-positive patients in whom cALND could safely be omitted. The Tenon score outperformed other scoring systems in a study by Coutant et al27
and includes characteristics that can be estimated at the time of the SLN biopsy. In the present study, we evaluated the Tenon score in a Swedish multicentre cohort. The AUC was only 0.65 and the performance of the score was thus inadequate in our patient cohort.
A validation study demonstrating good accuracy of the Tenon score was also presented by Coutant et al,36
with both studies from this group evaluating French populations. A French data set was also used to develop the Tenon score. In contrast, validation studies in other populations and also a recent French validation study demonstrate less prediction accuracy (AUC 0.58–0.70),29,37–39
which the results from our study are in accordance with. This could represent differences in populations, surgical technique or pathologic examination.
Unfortunately, we were not able to validate the Memorial Sloan-Kettering Cancer Center (MSKCC) nomogram24
in our population as we had incomplete information about the occurrence of lymphovascular invasion. The MSKCC nomogram has, however, been validated in several other studies, and the AUC varied between 0.58 and 0.86.27,39
In three studies the AUC was less than 0.70 (the limit used for considering an acceptable predictive ability), possibly reflecting population differences in a similar way as for the Tenon score.
Several studies have tried, but have been unable, to define a subgroup in which cALND can safely be omitted.8,13,40–43
In a meta-analysis by Degnim et al,8
no subgroup had less than a 10% risk of non-SLN metastases.
We could identify two groups of patients in whom the risk of non-SLN metastases was less than 10%. However, these were very small subgroups (n = 102 and 23, respectively) that were not pre-planned in the study and their clinical significance is therefore questionable. The results of our study, and most of the previously published, similar studies, indicate that the evaluation of primary tumour and SLN characteristics is not sufficient to decide whether to proceed with further axillary surgery.
Interestingly, only one of 86 SLN-positive patients in whom cALND was omitted had an isolated axillary recurrence. In accordance, a low incidence of axillary recurrence was previously demonstrated in other studies.10,12,44
In a review by Rutgers, the 2- to 3-year risk of axillary recurrence in SLN-positive patients was 0 to 1.4% if the axilla was left untreated.45
In part, this could be explained by better prognostic factors in the patients that did not have cALND, but many studies have reported the axillary recurrence rate to also be lower than expected in SLN- negative patients. Since the false negative rate is known to be about 5%–10%4,46–48
this indicates that not all positive lymph nodes left behind will develop into clinically significant metastases.
Recently, in a report on 97 314 patients who had breast cancer surgery between 1998 and 2005, Bilimoria et al49
found no significant difference in axillary recurrence or survival for SLN-positive patients who underwent SLNB alone compared with those who had cALND. It is, however, a retrospective study and the completeness of follow-up was not reported. Furthermore, between 1998 and 2000 the number of excised lymph nodes was almost as high in the SLNB as in the ALND group.
Additionally, the American College of Surgeons Oncology Group (ACO-SOG) Z0011 trial found no higher incidence of axillary recurrence50
and comparable survival17
in SLN-positive patients randomised to omission of cALND compared with those who completed an ALND after a median follow-up of 6.3 years. However, only 891 of the planned 1900 patients were accrued and the study was closed early. Considering the low accruement rate (despite many participating centres, several of these probably with large patient volumes), one cannot rule out the possibility of a significant selection bias, and included patients were at low risk for recurrence. Furthermore, all patients received whole-breast irradiation, including the lower part of the axilla.
We therefore believe that it is too early to abandon ALND for all SLN-positive patients.