A prospective validation study of sentinel lymph node biopsy in multicentric breast cancer: SMMaC trial. Eur J Surg Oncol. 2014;40:1250-1255. [PMID: 24685336 DOI: 10.1016/j.ejso.2013.11.004]

Evaluating the current evidence to support therapeutic mammoplasty or breast-conserving surgery as an alternative to mastectomy in the treatment of multifocal and multicentric breast cancers

The oncological safety of treating multiple ipsilateral breast cancers (MIBCs) with types of breast conserving surgery (BCS) compared to mastectomy remains uncertain. This is predicated on the absence of any randomised controlled trials or high-quality protocol defined prospective cohort studies. A single recently published systematic review by the first author, reports its summarised results in this review. Fundamentally the important question is the evaluation of clinical safety following BCS compared to mastectomy for treating MIBC, which is reported in only six studies. Consequently, current evidence doesn't support the latest St Gallen consensus suggesting the possibility of using BCS to treat all MIBC. There is minimal comparative outcomes data on multicentric (MC) cancers compared to multifocal (MF) cancers comparing BCS or mastectomy. There is also poor evidence of clinical outcomes following therapeutic mammoplasty (TM) for MIBC compared to mastectomy. The potential recommendation of two potential radiotherapy boosts to separate lumpectomy sites following BCS for MC cancers remains a novel treatment concept whose feasibility will be evaluated in the forthcoming NIHR funded randomised feasibility trial called MIAMI. This is a world first attempt to assess the feasibility of a randomised trial design alongside the on-going Alliance registry study (ACOSOG, American College of Surgeons Oncology Group Z11102) in the USA, in which there is no comparative evaluation of mastectomy outcomes. The MIAMI trial aims to assess the clinical safety of multiple lumpectomies combined with TM compared to the standard of mastectomy in MIBC stratified by MF or MC cancers. There is limited evidence on the impacts of inter-tumoral heterogeneity relating to breast cancer subtypes in relation to individualised treatments and recommendations for types of breast surgery. Recent studies have highlighted the potential contributions of stromal epigenetic changes that are currently poorly understood regarding their contributions to either clinical unifocal or MF cancers.

Is breast conservative surgery a reasonable option in multifocal or multicentric tumors?

The incidence of multifocal (MF) and multicentric (MC) carcinomas varies widely among clinical studies, depending on definitions and methods for pathological sampling. Magnetic resonance imaging is increasingly used because it can help identify additional and conventionally occult tumors with high sensitivity. However, false positive lesions might incorrectly influence treatment decisions. Therefore, preoperative biopsies must be performed to avoid unnecessary surgery. Most studies have shown higher lymph node involvement rates in MF/MC tumors than in unifocal tumors. However, the rate of local recurrences is usually low after breast conservative treatment (BCT) of MC/MF tumors. It has been suggested that BCT is a reasonable option for MC/MF tumors in women aged 50-69 years, with small tumors and absence of extensive ductal carcinoma in situ. A meta-analysis showed an apparent decreased overall survival in MC/MF tumors but data are controversial. Surgery should achieve both acceptable cosmetic results and negative margins, which requires thorough preoperative radiological workup and localization of lesions. Boost radiotherapy techniques must be evaluated since double boosts might result in increased toxicity, namely fibrosis. In conclusion, BCT is feasible in selected patients with MC/MF but the choice of surgery must be discussed in a multidisciplinary team comprising at least radiologists, surgeons and radiotherapists.

[Sentinel lymph node-multicentric and multifocal tumors: a valid technique?]

Sentinel node biopsy without complementary axillary lymph node dissection was validated for T1-2 N0 unifocal breast cancer without previous treatment since several years. In the situation of multifocal multicentric breast tumors, this procedure was considered as a contraindication. The aim of this work was to analyse literature results to determine if sentinel lymph node biopsy can be considered as a valid option without complementary axillary lymph node dissection for negative sentinel lymph node.

[Relevance of the sentinel lymph node biopsy in breast multifocal and multicentric cancer]

OBJECTIVES

The sentinel lymph node biopsy is a gold standard in the management of breast cancer. Its role in multifocal or multicentric tumors is still evolving. The aim of this study is to assess the feasibility and pertinence of sentinel lymph node biopsy in multifocal and multicentric tumors based on a systematic review of literature.

METHODS

A systematic review was conducted searching in the following electronic databases PubMed using "sentinel lymph node biopsy", "breast cancer", "multifocal tumor", "multicentric tumor" and "multiple tumor" as keywords. We included original articles published between 2000 and 2014, both French and English, studying feasibility of sentinel lymph node biopsy in invasive breast cancer, multicentric and/or multifocal tumors. The first end point was success rate and false negative rate.

RESULTS

Twenty-six articles were included in this literature review, with 2212 cases (782 multifocal, 737 multicentric and 693 multiple tumors). Percentage of tumors whose stage was higher than stage T2 ranged from 0 to 86.3%. Success rate average was 83.1%. False negative average was 8.2%. False negative rate was less than 10% in 15 articles. Mean of sentinel lymph node biopsy was 2 (1-9). The average rate of sentinel lymph node positive was 50.6%. Axillary recurrence rate was 0.5%.

CONCLUSION

Despite the methodological biases of the studies included in this review of literature, the false negative rate of sentinel node biopsy in multifocal and multicentric breast cancers are less than 10% with a low rate of axillary recurrence. Despite the lack of randomized study, this procedure can be routinely performed in accordance with rigorous technical process.