Results With Accelerated Partial Breast Irradiation in Terms of Estrogen Receptor, Progesterone Receptor, and Human Growth Factor Receptor 2 Status

Concurrent chemotherapy with partial breast irradiation in triple negative breast cancer patients may improve disease control compared with sequential therapy

Purpose

To report outcomes on a subset of patients with triple negative breast cancer (TNBC) treated on prospective trials with post-lumpectomy partial breast irradiation and concurrent chemotherapy (PBICC) and compare them to a retrospectively assessed similar cohort treated with whole breast irradiation after adjuvant chemotherapy (WBIaC).

Methods and materials

Women with T1-2, N0-1 invasive breast cancer with ≥ 2mm lumpectomy margins were offered therapy on one of two PBICC trials. PBI consisted of 40.5 Gy in 15 daily 2.7 Gy fractions delivered concurrently with the first 2 cycles of adjuvant chemotherapy. The comparison cohort received WBI to a median dose of 60.7 Gy, (including boost, range 42.5 - 66 Gy), after completion of non-concurrent, adjuvant chemotherapy. We evaluated disease-free survival (DFS), and local/loco-regional/distant recurrence-free survival (RFS). We compared survival rates using Kaplan-Meier curves and log-rank test of statistical significance.

Results

Nineteen patients with TNBC were treated with PBICC on prospective protocol, and 49 received WBIaC. At a median follow-up of 35.5 months (range 4.8-71.9), we observed no deaths in the PBICC cohort and 2 deaths in the WBIaC cohort (one from disease recurrence). With a median time of 23.4 (range 4.8 to 47) months, there were 7 recurrences (1 nodal, 4 local, 4 distant), all in the WBIaC group. At 5 years, there was a trend towards increased local RFS (100% vs. 85.4%, p=0.17) and loco-regional RFS (100% vs. 83.5, p=0.13) favoring the PBICC cohort. There was no significant difference in distant RFS between the two groups (100% vs. 94.4%, p=0.36). Five-year DFS was 100% with PBICC vs.78.9% (95% CI: 63.2 to 94.6%, p=0.08) with WBIaC.

Conclusion

This study suggests that PBICC may offer similar and possibly better outcomes in patients with TNBC compared to a retrospective cohort treated with WBIaC. This observation is hypothesis-generating for prospective trials.

Partial breast irradiation: An updated consensus statement from the American brachytherapy society

PURPOSE

In recent years, results with mature follow-up have been reported for several Phase III trials randomizing women to receive whole breast irradiation (WBI) versus varying modalities of partial breast irradiation (PBI). It is important to recognize that these methods vary in terms of volume of breast tissue treated, dose per fraction, and duration of therapy. As such, clinical and technical guidelines may vary among the various PBI techniques.

METHODS

Members of the American Brachytherapy Society with expertise in PBI performed an extensive literature review focusing on the highest quality data available for the numerous PBI options offered in the modern era. Data were evaluated for strength of evidence and published outcomes were assessed.

RESULTS

The majority of women enrolled on randomized trials of WBI versus PBI have been age >45 years with tumor size <3 cm, negative margins, and negative lymph nodes. The panel also concluded that PBI can be offered to selected women with estrogen receptor negative and/or Her2 amplified breast cancer, as well as ductal carcinoma in situ, and should generally be avoided in women with extensive lymphovascular space invasion.

CONCLUSIONS

This updated guideline summarizes published clinical trials of PBI methods. The panel also highlights the role of PBI for women facing special circumstances, such as history of cosmetic breast augmentation or prior breast irradiation, and discusses promising novel modalities that are currently under study, such as ultrashort and preoperative PBI. Updated consensus guidelines are also provided to inform patient selection for PBI and to characterize the strength of evidence to support varying PBI modalities.

RHAMM splice variants confer radiosensitivity in human breast cancer cell lines

Biomarkers for prognosis in radiotherapy-treated breast cancer patients are urgently needed and important to stratify patients for adjuvant therapies. Recently, a role of the receptor of hyaluronan-mediated motility (RHAMM) has been suggested for tumor progression. Our aim was (i) to investigate the prognostic value of RHAMM in breast cancer and (ii) to unravel its potential function in the radiosusceptibility of breast cancer cells. We demonstrate that RHAMM mRNA expression in breast cancer biopsies is inversely correlated with tumor grade and overall survival. Radiosusceptibility in vitro was evaluated by sub-G1 analysis (apoptosis) and determination of the proliferation rate. The potential role of RHAMM was addressed by short interfering RNAs against RHAMM and its splice variants. High expression of RHAMMv1/v2 in p53 wild type cells (MCF-7) induced cellular apoptosis in response to ionizing radiation. In comparison, in p53 mutated cells (MDA-MB-231) RHAMMv1/v2 was expressed sparsely resulting in resistance towards irradiation induced apoptosis. Proliferation capacity was not altered by ionizing radiation in both cell lines. Importantly, pharmacological inhibition of the major ligand of RHAMM, hyaluronan, sensitized both cell lines towards radiation induced cell death. Based on the present data, we conclude that the detection of RHAMM splice variants in correlation with the p53 mutation status could help to predict the susceptibility of breast cancer cells to radiotherapy. Additionally, our studies raise the possibility that the response to radiotherapy in selected cohorts may be improved by pharmaceutical strategies against RHAMM and its ligand hyaluronan.

Outcomes According to Breast Cancer Subtype in Patients Treated With Accelerated Partial Breast Irradiation

BACKGROUND

The purpose of the study was to determine outcomes for patients treated with accelerated partial breast irradiation (APBI) on the basis of breast cancer subtype (BCST).

PATIENTS AND METHODS

Our single-institution, institutional review board-approved APBI database was queried for patients who had complete testing results for the estrogen (ER), progesterone (PR), and HER2/neu receptors to determine outcomes for each BCST. Women were assigned as luminal A (LA), luminal B (LB), HER2, and basal BCST using their ER, PR, and HER2/neu receptor status. Degree of ER expression supplemented the receptor-based luminal BCST assignment. Two hundred seventy-eight patients had results for all 3 receptors (LA = 164 [59%], LB = 81 [29%], HER2 = 5 [2%], basal = 28 [10%]), which were submitted for analysis (ipsilateral breast tumor recurrence [IBTR], regional nodal failure, distant metastasis [DM], disease-free survival [DFS], cause-specific survival [CSS], and overall survival [OS]).

RESULTS

Median follow-up was 5.4 years (range, 0.1-12.4 years). Basal and HER2 subtype patients had higher histologic grades (Grade 3 = 75% vs. 10% LA/LB; P < .001), larger tumors (13.0 mm basal vs. 10.7 mm LA/LB; P = .059), and were more likely to receive chemotherapy (68% vs. 15% LA/LB; P < .001). Margin and nodal status were similar among BCSTs. At 5 years, IBTR rates were similar (1.8%, 2.9%, 0%, and 4.8%) for LA, LB, HER2, and basal subtypes, respectively (P = .62). DM was only seen in LA (2.9%) and LB (1.3%) (P = .83). DFS (95%-100%), CSS (97%-100%), and OS (80%-100%) were not statistically different (P = .97, .87, .46, respectively).

CONCLUSION

Five-year local control rates after breast-conserving surgery, APBI, and appropriate systemic therapy are excellent for luminal, HER2, and basal phenotypes of early-stage breast cancer; however, further study of receptor subtype effect on risk stratification in early-stage breast cancer is needed.

Accelerated partial breast irradiation with brachytherapy: patient selection and technique considerations

Accelerated partial breast irradiation (APBI) through breast brachytherapy is a relatively recent development in breast radiotherapy that has gained international favor because of its reduction in treatment duration and normal tissue irradiation while maintaining favorable cancer-specific and cosmetic outcomes. Despite the fact that several large national trials have not reported final results yet, many providers are currently offering APBI to select patients and APBI is listed as a treatment option for selecting patients in the National Comprehensive Cancer Network guidelines. Multiple consensus guidelines exist in selecting patients for APBI, some with conflicting recommendations. In this review, the existing patient selection guidelines are reported, compared, and critiqued, grouping them in helpful subcategories. Unique patient and technical selection factors for APBI with brachytherapy are explored.

Radiation therapy in the locoregional treatment of triple-negative breast cancer

This Review assesses the relevant data and controversies regarding the use of radiotherapy for, and locoregional management of, women with triple-negative breast cancer (TNBC). In view of the strong association between BRCA1 and TNBC, knowledge of baseline mutation status can be useful to guide locoregional treatment decisions. TNBC is not a contraindication for breast conservation therapy because data suggest increased locoregional recurrence risks (relative to luminal subtypes) with breast conservation therapy or mastectomy. Although a boost to the tumour bed should routinely be considered after whole breast radiation therapy, TNBC should not be the sole indication for post-mastectomy radiation, and accelerated delivery methods for TNBC should be offered on clinical trials. Preliminary data implying a relative radioresistance for TNBC do not imply radiation omission because radiation provides an absolute locoregional risk reduction. At present, the integration of subtypes in locoregional management decisions is still in its infancy. Until level 1 data supporting treatment decisions based on subtypes are available, standard locoregional management principles should be adhered to.

Outcome of a phase II prospective study on partial breast irradiation with interstitial multi-catheter high-dose-rate brachytherapy

BACKGROUND AND PURPOSE

Partial breast irradiation (PBI) is an alternative to whole-breast irradiation after breast-conserving surgery in selected patients. Until the results of randomized phase III studies are available, phase II studies inform about PBI. We report the 5 year results of a phase II prospective study with PBI using interstitial multi-catheter high-dose-rate brachytherapy (ClinicalTrials.gov Identifier: NCT00499057).

METHODS

Hundred patients received PBI (4 Gy, twice a day for 4 days, until 32 Gy). Inclusion criteria were: age ≥ 40years, infiltrating carcinoma without lobular histology, ductal in situ carcinoma, tumor size ≤ 2.5 cm, negative surgical margins and axillary lymph nodes.

RESULTS

At a median follow-up of 60 months late toxicity occurred in 25 patients; the 5-year probability of freedom from late toxicity was 72.6% (95% CI: 63.7-81.7). Tamoxifen was the only significant risk factor for late toxicity. Cosmetic results, judged by physicians and patients, were good/excellent in 98 patients. Three local relapses (1 true, 2 elsewhere) and 1 regional relapse occurred. The 5-year probability of local or regional relapse-free survival was 97.7% (95% CI: 91.1-99.4) and 99.0% (95% CI: 92.9-99.8), respectively.

CONCLUSION

PBI with interstitial multi-catheter brachytherapy is associated with low relapse and late toxicity rates.

Silencing CDK4 radiosensitizes breast cancer cells by promoting apoptosis

Background

The discovery of molecular markers associated with various breast cancer subtypes has greatly improved the treatment and outcome of breast cancer patients. Unfortunately, breast cancer cells acquire resistance to various therapies. Mounting evidence suggests that resistance is rooted in the deregulation of the G1 phase regulatory machinery.

Methods

To address whether deregulation of the G1 phase regulatory machinery contributes to radiotherapy resistance, the MCF10A immortalized human mammary epithelial cell line, ER-PR-Her2+ and ER-PR-Her2- breast cancer cell lines were irradiated. Colony formation assays measured radioresistance, while immunocytochemistry, Western blots, and flow cytometry measured the cell cycle, DNA replication, mitosis, apoptosis, and DNA breaks.

Results

Molecular markers common to all cell lines were overexpressed, including cyclin A1 and cyclin D1, which impinge on CDK2 and CDK4 activities, respectively. We addressed their potential role in radioresistance by generating cell lines stably expressing small hairpin RNAs (shRNA) against CDK2 and CDK4. None of the cell lines knocked down for CDK2 displayed radiosensitization. In contrast, all cell lines knocked down for CDK4 were significantly radiosensitized, and a CDK4/CDK6 inhibitor sensitized MDA-MB-468 to radiation induced apoptosis. Our data showed that silencing CDK4 significantly increases radiation induced cell apoptosis in cell lines without significantly altering cell cycle progression, or DNA repair after irradiation. Our results indicate lower levels of phospho-Bad at ser136 upon CDK4 silencing and ionizing radiation, which has been shown to signal apoptosis.

Conclusion

Based on our data we conclude that knockdown of CDK4 activity sensitizes breast cancer cells to radiation by activating apoptosis pathways.

External beam accelerated partial-breast irradiation using 32 gy in 8 twice-daily fractions: 5-year results of a prospective study

PURPOSE

External beam accelerated partial breast irradiation (APBI) is an increasingly popular technique for treatment of patients with early stage breast cancer following breast-conserving surgery. Here we present 5-year results of a prospective trial.

METHODS AND MATERIALS

From October 2003 through November 2005, 98 evaluable patients with stage I breast cancer were enrolled in the first dose step (32 Gy delivered in 8 twice-daily fractions) of a prospective, multi-institutional, dose escalation clinical trial of 3-dimensional conformal external beam APBI (3D-APBI). Median age was 61 years; median tumor size was 0.8 cm; 89% of tumors were estrogen receptor positive; 10% had a triple-negative phenotype; and 1% had a HER-2-positive subtype. Median follow-up was 71 months (range, 2-88 months; interquartile range, 64-75 months).

RESULTS

Five patients developed ipsilateral breast tumor recurrence (IBTR), for a 5-year actuarial IBTR rate of 5% (95% confidence interval [CI], 1%-10%). Three of these cases occurred in patients with triple-negative disease and 2 in non-triple-negative patients, for 5-year actuarial IBTR rates of 33% (95% CI, 0%-57%) and 2% (95% CI, 0%-6%; P<.0001), respectively. On multivariable analysis, triple-negative phenotype was the only predictor of IBTR, with borderline statistical significance after adjusting for tumor grade (P=.0537).

CONCLUSIONS

Overall outcomes were excellent, particularly for patients with estrogen receptor-positive disease. Patients in this study with triple-negative breast cancer had a significantly higher IBTR rate than patients with other receptor phenotypes when treated with 3D-APBI. Larger, prospective 3D-APBI clinical trials should continue to evaluate the effect of hormone receptor phenotype on IBTR rates.

Triple negative breast cancer is associated with an increased risk of residual invasive carcinoma after lumpectomy

BACKGROUND

To assess the potential mechanisms that may underlie increased local failure in triple negative (TN) breast cancers, an analysis was performed of the risk of residual carcinoma after lumpectomy with correlation to pathologic factors, including molecular phenotype.

METHODS

A review of pathologic specimens was performed for women with invasive breast cancer treated with lumpectomy followed by reexcision. Data were collected on age; tumor size, grade, and nodal stage; estrogen receptor, progesterone receptor, and human endothelial growth factor receptor 2 (Her2); extensive intraductal component; lymphovascular invasion; margins; and reexcision findings. Univariate and multivariate logistic regression analyses were performed to evaluate for associations between pathologic features of the lumpectomy specimen and reexcision findings. Molecular phenotypes were defined by conventionally used immunohistochemical pattern.

RESULTS

Data were collected on 369 patients with breast cancer. The median age was 57 years, median tumor size was 1.5 cm, 36% had positive margins, 32% had positive lymph nodes, 73.5% had the luminal A subtype, 9.5% had the luminal B subtype, 4.5% were Her2-enriched, and 12.5% were TN. Overall, 32% of patients had invasive cancer in their reexcision specimens, and 51% of those with the TN subtype had residual invasive disease on reexcision compared with 30% to 31% for other subtypes. On univariate analysis, age, tumor size, margin status, lymphovascular invasion, nodal status, and TN subtype were associated with elevated risk of residual invasive cancer. On multivariate analysis using a forward stepwise model, TN subtype maintained significance, with an odds ratio of 3.28 (P = .002).

CONCLUSION

TN subtype has a statistically significant association with an increased risk of residual tumor. This suggests the putative increase in the risk of local failure in TN patients may be related to increased residual tumor burden.

Adjuvant chemotherapy and radiotherapy in triple-negative breast carcinoma: a prospective randomized controlled multi-center trial

BACKGROUND AND PURPOSE

Triple-negative breast cancer (TNBC) presents a high risk breast cancer that lacks the benefit from hormone treatment, chemotherapy is the main strategy even though it exists in poor prognosis. Use of adjuvant radiation therapy, which significantly decreases breast cancer mortality, has not been well described among poor TNBC women. The aim of this study was to evaluate whether the combination of chemotherapy and radiotherapy could significantly increase survival outcomes in TNBC women after mastectomy.

PATIENTS AND METHODS

A prospective randomized controlled multi-center study was performed between February 2001 and February 2006 and comprised 681 women with triple-negative stage I-II breast cancer received mastectomy, of them, 315 cases received systemic chemotherapy alone, 366 patients received radiation after the course of chemotherapy. Recurrence-free survival (RFS) and overall survival (OS) were estimated. Simultaneously local and systemic toxicity were observed.

RESULTS

After a median follow-up of 86.5 months, five-year RFS rates were 88.3% and 74.6% for adjuvant chemotherapy plus radiation and adjuvant chemotherapy alone, respectively, with significant difference between the two groups (HR 0.77 [95% CI 0.72, 0.98]; P=0.02). Five-year OS significantly improved in adjuvant chemotherapy plus radiation group compared with chemotherapy alone (90.4% and 78.7%) (HR 0.79 [95% CI 0.74, 0.97]; P=0.03). No severe toxicity was reported.

CONCLUSIONS

Patients received standard adjuvant chemotherapy plus radiation therapy was more effective than chemotherapy alone in women with triple-negative early-stage breast cancer after mastectomy.

The implications of breast cancer molecular phenotype for radiation oncology

The identification of distinct molecular subtypes of breast cancer has advanced the understanding and treatment of breast cancer by providing insight into prognosis, patterns of recurrence, and effectiveness of therapy. The prognostic significance of molecular phenotype with regard to distant recurrences and overall survival are well established in the literature and has been readily incorporated into systemic therapy management decisions. However, despite the accumulating data suggesting similar prognostic significance for locoregional recurrence, integration of molecular phenotype into local management decision making has lagged. Although there are some conflicting reports, collectively the literature supports a low risk of local recurrence (LR) in the hormone receptor (HR) positive luminal subtypes compared to HR negative subtypes [triple negative (TN) and HER2-enriched]. The development of targeted therapies, such as trastuzumab for the treatment of HER2-enriched subtype, has been shown to mitigate the increased risk of LR. Unfortunately, no such remedy exists to address the increased risk of LR for patients with TN tumors, making it a clinical challenge for radiation oncologists. In this review we discuss the correlation between molecular subtype and LR following either breast conservation therapy or mastectomy. We also explore the possible mechanisms for increased LR in TN breast cancer and radiotherapeutic implications for this population, such as the safety of breast conservation, consideration of dose escalation, and the appropriateness of accelerated partial breast irradiation.