Sentinel node biopsy for breast cancer larger than 3 cm in diameter.

Sentinel node biopsy for breast cancer larger than 3 cm in diameter Schule J, Frisell J, Ingvar C and Bergkvist L British Journal of Surgery, 2007, 94, 948-951

Sentinel lymph-node biopsy is now well established to stage the axilla in early breast cancer. Randomised trials that addressed the role of sentinel node biopsy have focused on smaller tumours and the majority of published series include only limited numbers of larger breast cancers. The accuracy of sentinel node biopsy in larger breast primary cancers has been questioned, with false-negative rates likely to exceed the accepted 5-10% level.

This paper from Sweden investigates a prospective sentinel node biopsy database consisting of over 6300 patients registered since establishment of the procedure in 1997. Exclusions included primary medical therapy, previous breast surgery and multifocal cancer diagnosed before surgery. The authors evaluated the false-negative rate of sentinel node biopsy in patients who had both sentinel node biopsy and axillary node dissection regardless of the outcome of sentinel node biopsy. The dual localisation technique of radioisotope and blue dye was used.

A total of 109 women who met the inclusion criteria with tumours greater than 3 cm were studied. The median patient age was 55 (range, 35-84) years. The primary tumour size ranged from 31-80 (median, 40) mm, and included 94 T2 tumours (86.2%) and 15 T3 tumours (13.8%).

The overall false-negative rate of sentinel node biopsy in primary breast cancers [greater than or equal to] 3 cm was 8/64 (13%). Although multifocal tumours diagnosed pre-surgery were excluded, a number were diagnosed pathologically that were not identified pre-operatively. The rate of nodal metastases was higher in patients with unexpected multifocal tumours [13/16 (81%) versus 54/93 (58%); P=0.091] as was the false-negative rate compared with women with unifocal tumours [4/13 (31%) versus 4/51 (8%); P=0.012]. The technical failure rate of tumours [greater than or equal to] 3 cm was not different from in previous studies on sentinel node biopsy in all comers.

As observed in other studies, the false-negative rate of sentinel node biopsy in this study for larger primary breast cancers was higher and outside the range of what is normally considered acceptable for the accuracy of the procedure. These findings impact on what information we should provide to patients to obtain informed consent and to enable patient choice in accepting sentinel node biopsy when associated with larger tumours.

Patients with larger breast cancers are more likely to be offered primary chemotherapy. Studies that have considered the role of sentinel node biopsy after primary chemotherapy have included a range of tumour sizes, pathological variables and modes of clinical presentation [1]. The higher false-negative rate of sentinel node biopsy following primary chemotherapy may well be due to the inherent lower accuracy of the technique when applied to larger tumours rather than the process of response to chemotherapy.

This study did not seek to evaluate multifocality as a primary endpoint and indeed those with established multifocal disease pre-surgery were excluded. The finding that multifocal breast cancer in larger tumours is associated with an increased false-negative rate of sentinel node biopsy is a clinically relevant observation. Surgeons need to evaluate and decide how best to counsel patients and manage the axilla in women with larger primary breast cancers within individual tumour networks.

Reference

[1.] Xing Y, Foy M, Cox DD et al. Meta-analysis of sentinel lymph node biopsy after preoperative chemotherapy in patients with breast cancer. Br J Surg, 2006, 93, 539-546.