Width of margins in phyllodes tumors of the breast: the controversy drags on?-a systematic review and meta-analysis

Purpose: Phyllodes tumors (PT) of the breast are rare fibroepithelial neoplasms. Information is controversial in the literature regarding to the optimal surgical management. Most studies suggested margins of at least 10 mm while some recent studies suggested narrower margins without an increased risk of local recurrences (LR) and distant metastases (DM). The objective of this systematic review was to identify and compare studies that assessed these different practices.

Methods: A systematic review was performed through five databases up to April 2019. Studies exploring the association between the width of margins, subtypes of PT, and the LR and DM rates were considered for inclusion. A statistical model for analyzing sparse data and rare events was used.

Results: Thirteen studies met eligibility criteria and were selected. Considering a threshold of 10 mm (margins < 10 vs margins ≥ 10 mm), the 5-year incidence rate of LR was estimated to be 5.22 vs. 3.63 (diff. -1.59) per 100 person-years for benign PT, 9.60 vs. 7.33 (diff. -2.27) for borderline PT, and 28.58 vs. 21.84 (diff. -6.74) for malignant PT. For DM, it was estimated to be 0.88 vs. 0.86 (diff. -0.02) for benign PT, 1.61 vs. 1.74 (diff. 0.13) for borderline PT, and 4.80 vs 5.18 (diff. 0.38) for malignant PT. The data for a threshold of 1 mm were not sufficient to draw any conclusions.

Conclusion: Irrespective of tumor grade, we found that DM was a rarer event than LR. Malignant PT had the highest incidence rate of LR and DM. This meta-analysis found a clear association between width of margins and LR rates. Whatever the tumor grade, surgical margins ≥ 10 mm guaranteed a lower risk of LR than margins < 10 mm. On the other hand, the width of margin did not influence the apparition of DM.

Keywords: Breast cancer; Distant metastasis; Local recurrence; Phyllodes tumor; Surgical margins.