Prediction of response to neoadjuvant chemotherapy by MammaTyper® across breast cancer subtypes: A retrospective cross-sectional study.

BACKGROUND: Neoadjuvant chemotherapy (NACT) is widely used in the treatment of triple-negative and HER2-positive breast cancer (BC), but its use in estrogen receptor (ER) and/or progesterone receptor (PR) positive/HER2-negative BC is questioned because of the low pathologic complete response (pCR) rates. This retrospective study assessed the mRNA-based MammaTyper® assay's capability of predicting pCR with NACT, and ER, PR, Ki67, and HER2 status at immunohistochemical (IHC) through transcriptomics. METHODS: Diagnostic biopsies from 76 BC patients treated at the Cremona Hospital between 2012-2018 were analyzed. Relative mRNA expression levels of ERBB2, ESR1, PGR, and MKI67 were measured using the MammaTyper® kit and integrated into a pCR score. Predicting capability of pCR and standard IHC biomarkers could be assessed with ROC curves in 75 and 76 patients, respectively. RESULTS: Overall, 68.0% patients obtained a MammaTyper® high-score and 32.0% a MammaTyper® low-score. Among high-score patients, 62.7% achieved pCR, compared to 16.7% in the low-score group (p = 0.0003). The binary MammaTyper® score showed good prediction of pCR in the overall cohort (area under curve [AUC] = 0.756) and in HR+/HER2-negative cases (AUC = 0.774). In cases with residual disease, the continuous MammaTyper® score correlated moderately with residual tumor size and decrease in tumor size. MammaTyper® showed substantial agreement with IHC for ESR1/ER and ERBB2/HER2, and moderate agreement for PGR/PR and MKI67/Ki67. CONCLUSION: Overall, MammaTyper® pCR score may serve as a standardized tool for predicting NACT response in HR+/HER2-negative BC, potentially guiding treatment strategies. Additionally, it could provide a more standardized and reproducible assessment of ER, PR, HER2, and Ki67 status.

Ten daily fractions for partial breast irradiation. Long-term results of a prospective phase II trial.

Partial breast irradiation (PBI) is an effective adjuvant treatment after breast conservative surgery for selected early-stage breast cancer patients. However, the best fractionation scheme is not well defined. Hereby, we report the 5-year clinical outcome and toxicity of a phase II prospective study of a novel regimen to deliver PBI, which consists in 40 Gy delivered in 10 daily fractions. Patients with early-stage (pT1-pT2, pN0-pN1a, M0) invasive breast cancer were enrolled after conservative surgery. The minimum age at diagnosis was 60 years old. PBI was delivered with 3D-conformal radiotherapy technique with a total dose of 40 Gy, fractionated in 10 daily fractions (4 Gy/fraction). Eighty patients were enrolled. The median follow-up was 67 months. Five-year local control (LC), disease-free survival (DFS), and overall survival (OS) were 95%, 91%, and 96%, respectively. Grade I and II subcutaneous fibrosis were documented in 23% and 5% of cases. No grade III late toxicity was observed. PBI delivered in 40 Gy in 10 daily fractions provided good clinical results and was a valid radiotherapy option for early-stage breast cancer patients.

Seven fractions to deliver partial breast irradiation: the toxicity is Low.

PURPOSE: To assess toxicity and clinical outcome, in breast cancer patients treated with external beam partial breast irradiation (PBI) consisting of 35 Gy in 7 daily fractions (5 Gy/fraction). MATERIALS AND METHODS: Patients affected by early-stage breast cancer were enrolled in this phase II trial. Patients had to be 60 years old or over and treated with breast conservative surgery for early stage invasive carcinoma. RESULTS: Seventy-three patients were analyzed. Median follow-up was 40 months. The proposed schedule was well tolerated. No Grade 3 toxicity was documented. Late toxicity was assessable for all the treated patients. Two patients (2.7%) developed Grade 2 pain 6 months after PBI. Four patients (5%) developed asymptomatic fat necrosis. Grade 2 fibrosis was observed in 5 patients (6.7%). No correlation was found between early and late toxicity and the type of adjuvant systemic therapy (no therapy vs. hormonal therapy vs. chemotherapy). No statistical correlation between dosimetric parameters and toxicity was found. Patients who developed Grade 2 radiation fibrosis had not higher radiation volumes to the untreated normal breast than those without fibrosis. Cosmesis was judged good/excellent in the majority of the cases (93%). One patient relapsed locally, and one developed distant metastases, corresponding to a 5-year local control and distant metastases-free survival of 98% and 96.7%, respectively. CONCLUSIONS: 35 Gy in 7 daily fractions is an effective and well-tolerated regimen to deliver PBI.

Toxicity and cosmesis following partial breast irradiation consisting of 40 Gy in 10 daily fractions.

PURPOSE: To assess the toxicity and cosmetic results in breast cancer patients undergoing adjuvant partial breast irradiation (PBI) to a total dose of 40 Gy in 10 daily fractions (4 Gy/fraction). METHODS AND MATERIALS: Patients affected by early-stage breast cancer were enrolled in this phase II trial. Patients had to be 60 years old and treated with breast conservative surgery for early stage (pT1-T2 pN0-N1a) invasive ductal carcinoma. RESULTS: 77 patients were enrolled. Median follow-up was 18 months. The proposed schedule was well tolerated. One patient reported Grade 3 pain at the site of irradiation. Four (5%) patients experience Grade 2 erythema. Late Grade 2 and 1 fibrosis was observed in 3 (4%) and 14 (18%) patients, respectively. Cosmesis was judged "good/excellent" and "poor" in 75 (97%) and in 2 (3%) patients, respectively. CONCLUSIONS: 40 Gy in 10 daily fractions, 4 Gy/fraction, is a well tolerated regimen to deliver PBI.