Published in:
01-11-2013 | Invited Commentary
Margin negative, breast conserving resection: adequate for benign phyllodes tumors, but inadequate therapy for borderline and malignant phyllodes tumors
Published in: Breast Cancer Research and Treatment | Issue 2/2013
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Dr. Kim and the authors of this retrospective review of their institution’s experience with phyllodes tumors are to be congratulated for their detailed categorization of local recurrence rates for each grade of phyllodes tumor as a function of the type of surgery and the margin status [1]. Several important observations deserve to be highlighted.
(1)
Phyllodes tumors are uncommon breast tumors, but are not rare Over a 10-year period 3 % of the breast neoplasms were phyllodes tumors. Benign phyllodes tumors were about ten times more common than malignant, and about five times more common than borderline. In a busy surgical practice of 400 cases per year one could expect to see 12 patients with phyllodes tumors: nine benign, two borderline, and one malignant.
(2)
Margin negative resection of benign phyllodes tumors is associated with a very low incidence of local recurrence Many previous studies have described the result of local excision or wide local excision of benign phyllodes tumors, without clearly delineating the margin status. In a review of several of these studies in 1999, we found that benign phyllodes tumors recurred after local excision in 21 % of cases and after wide local excision in 8 % [2]. Since one may have a positive margin even after an attempted wide local excision, the key variable is the margin status. Kim et al. have now described 114 patients who underwent margin negative, breast conserving resections of benign phyllodes tumors with only four local recurrences (3.5 %). Achieving a margin negative resection, while optimizing cosmesis by excising a minimal amount of surrounding breast tissue is optimal treatment for patients with benign phyllodes tumors.
(3)
The histologic grade of phyllodes tumor (benign vs borderline vs malignant) predicts the likelihood of local recurrence after margin negative resection Kim et al. report that the chance of a local recurrence after breast conserving, margin negative resection of benign, borderline, and malignant phyllodes tumors is 4/114 (3.5 %), 4/23 (17.4 %), and 5/10 (50 %), respectively.
(4)
The risk of local recurrence after margin negative resection of borderline or malignant phyllodes tumors is substantial We have previously reviewed the literature on the incidence of local recurrence after margin negative breast conserving resection of borderline and malignant phyllodes tumors [3]. In that review, 12/50 (24 %) patients with borderline phyllodes tumors and 25/124 (20 %) patients with malignant phyllodes tumors locally recurred. Adding the data from Kim et al., the risk of local recurrence after margin negative breast conserving resection of borderline and malignant phyllodes tumors is 16/73 (22 %), and 30/134 (22 %), respectively.
The similarity in rates of local recurrence of borderline and malignant phyllodes tumors may be explained by recent molecular evidence that these tumor grades share similar genetic profiles. Comparative genomic hybridization analyses, which quantify chromosomal copy number gains and losses, indicate that phyllodes tumors segregate into two groups, with the borderline and malignant group having much greater chromosomal changes than benign phyllodes tumors [4]. Furthermore, mRNA expression profiling studies have shown that several genes are upregulated in borderline/malignant phyllodes tumors when compared to benign phyllodes tumors [5].
5.
Recurrent phyllodes tumors may be a higher grade than the initial tumor In this series by Kim et al. three of the six local recurrences after initial resections of borderline phyllodes tumors were malignant. One of these patients developed lung metastases.
6.
Malignant phyllodes tumors metastasize in 10–40 % of patients In this series by Kim et al. six of the 15 patients (40 %) with malignant phyllodes tumors developed lung metastases and died.