The Impact of Radiotherapy and Histological Risk Factors on Outcomes in Malignant Phyllodes Tumors.

PURPOSE: Breast phyllodes tumors (PT) are classified into benign, borderline, and malignant grades based on histopathologic characteristics. Specific to malignant PT (MPT), surgery is the mainstay yet relapse rates are high and knowledge gaps in the literature exist regarding adjuvant radiotherapy (RT). We aimed to investigate the outcomes of patients with MPT treated in a tertiary Asian institution. METHODS AND MATERIALS: Patients with nonmetastatic MPT treated from February 1992 to June 2019 were analyzed retrospectively. RT details and relapse fields were studied. Outcomes of patients with and without RT were compared and hazard ratios were calculated using Cox proportional hazard test. Multivariable analysis was performed. RESULTS: Twenty-two of 89 patients received adjuvant RT and the median dose was 60 Gy. In the no-RT group, 4 patients received RT on relapse and had no further recurrences; a further 2 received RT for fungating relapses with good symptomatic relief. RT was only increasingly prescribed after 2004. Median follow-up in the RT group was 3.31 years, compared with 6.17 years in the no-RT group. In the RT group, 15 patients (68.2%) underwent mastectomy, versus 39 (58.2%) in the no-RT group. One patient in the RT group developed an infield local relapse, compared with 21 of 67 patients in the no-RT group. Multivariate model showed that RT decreased risk of locoregional failure (hazard ratio 0.12, 95% confidence interval [CI] 0.02-0.92, P = .04). Three-year locoregional recurrence-free survival was higher in the RT group, 92.3% (95% CI, 78.9-100) versus 73.3% (95% CI, 63.1-85.1) in the no-RT group (P = .03). There were no differences in 3-year survival. CONCLUSIONS: We recommend that adjuvant radiotherapy be discussed for malignant PT for local control, even after mastectomy.

Comparing the Diagnostic Outcomes of Staining Various Breast Lesions with Either Anti-CK 5/6 or Anti-CK 5.

BACKGROUND AND OBJECTIVE: Anti-CK5/6 monoclonal antibodies have an established role in breast disease diagnosis. Anti-CK5 monoclonal antibodies have recently become commercially available. There has been growing interest in the staining characteristics of anti-CK5 and its potential diagnostic role in place of anti-CK5/6. We aim to compare and contrast the staining characteristics of anti-CK5/6 vs anti-CK5. MATERIAL AND METHODS: 58 tissue blocks containing 122 different lesions were selected from tissue archives. Two specimens (groups) were taken from each lesion One (group) was stained with anti-CK5 and the other (group) with anti-CK5/6 monoclonal antibodies, using the Streptavidin-biotin immuno-peroxidase method. The two groups of slides were compared and contrasted for lesion staining pattern and for intensity, using light microscopy. RESULTS: Results showed that the diagnostic staining pattern was exactly the same in both anti-CK5 and anti-CK5/6 groups, and also showed that anti-CK5, stained most of the lesions more intensely than anti-CK5/6. CONCLUSION: Anti-CK5 performed at least as well (for lesion-pattern staining), and better (for lesion staining intensity) than did anti-CK5/6 in the diagnosis of a wide range of breast tissues and lesions. It may be justified to safely replace anti-CK5/6 with anti-CK5 in future routine clinical use, with resultant diagnostic and economic benefits.