Early Breast Cancer Trialists' Collaborative Group. Radiotherapy for early breast cancer

Dosimetric comparison between interstitial brachytherapy and volumetric-modulated arc therapy for tumor bed boost in breast cancer

Purpose

To dosimetrically compare high-dose-rate interstitial brachytherapy (HDR-BT) with volumetric-modulated arc therapy (VMAT) for tumor bed boost, following breast conservative treatment.

Material and methods

50 patients with early-stage breast cancer who underwent breast conservation surgery, followed by either HDR-BT (n = 25) of 15 Gy in 6 fractions over a period of 3 days, or VMAT dose of 16 Gy in 8 fractions (n = 25) for tumor bed boost, were retrospectively reviewed. All patients received whole breast irradiation of 46 Gy in 23 fractions. Dosimetric parameters for organs at risk (OARs), including ipsilateral and contralateral lungs, heart, contralateral breast, skin, and ribs, were evaluated with the help of dose-volume histograms (DVH).

Results

Heart sparing was similar in both modalities (left-sided breast irradiation, HDR-BT D_2cc 20.5% vs. VMAT 30.2%, p-value = 0.243; right-sided breast irradiation, D_2cc 6.5% vs. 4.4%, p-value = 0.165). Left-sided cases received higher dose to heart compared to right-sided patients. Interstitial brachytherapy resulted in significantly less dose to contralateral breast (D_2cc 4.3% vs. 9.6%, p-value < 0.0001), ipsilateral lung (D_2cc 27.6% vs. 73.2%, p-value < 0.0001), contralateral lung (D_2cc 4.2% vs. 14.5%, p-value < 0.0001), ribs (D_2cc 24.1% vs. 41.2%, p-value < 0.0001), and skin (D_2cc 77.3% vs. 95%, p-value < 0.0001).

Conclusions

HDR-BT-based tumor bed boost irradiation results in significantly lower doses to most organs at risk with similar heart sparing compared to VMAT.

Adaptive radiation therapy of breast cancer by repeated imaging during irradiation

Breast cancer is the most frequent cancer among females and also a leading cause of cancer related mortality worldwide. A multimodality treatment approach may be utilized for optimal management of patients with combinations of surgery, radiation therapy (RT) and systemic treatment. RT composes an integral part of breast conserving treatment, and is typically used after breast conserving surgery to improve local control. Recent years have witnessed significant improvements in the discipline of radiation oncology which allow for more focused and precise treatment delivery. Adaptive radiation therapy (ART) is among the most important RT techniques which may be utilized for redesigning of treatment plans to account for dynamic changes in tumor size and anatomy during the course of irradiation. In the context of breast cancer, ART may serve as an excellent tool for patients receiving breast irradiation followed by a sequential boost to the tumor bed. Primary benefits of ART include more precise boost localization and potential for improved normal tissue sparing with adapted boost target volumes particularly in the setting of seroma reduction during the course of irradiation. Herein, we provide a concise review of ART for breast cancer in light of the literature.

Predictive Value of Primary Tumor Site for Loco-regional Recurrence in Early Breast Cancer Patients with One to Three Positive Axillary Lymphadenophy

Introduction: It remains controversial on high risks for early breast cancer patients with one to three axillary nodes after mastectomy who is predisposition to locoregional recurrence. The present study is to investigate the relationship between primary tumor site and loco-regional recurrence (LRR) and explore the predictive value of clinicopathological characteristics in LRR for early breast cancer patients with one to three positive axillary lymph nodes after mastectomy. Methods: We reviewed the clinical data of 656 consecutively diagnosed patients with pT_1-2N₁M₀ breast cancer who were treated in Sun Yat-sen University Cancer Center with radical operation without postoperative radiotherapy between March 1998 and December 2010. The primary tumor sites included outer quadrant in 455 patients (69.36%), inner quadrant in 156 patients (23.78%)and central quadrant in 45 patients (6.86%). LRR and LRR-free survival (LRFS) in combination with clinical and pathological features were analyzed to screen out patients with higher risk of LRR. Results: The median follow-up time was 64.9 months. The 5-, 10-year LRR for the cohort was 8.6% and 12.9%, respectively; the 5-, 10-year LRFS was 86.2% and 76.4%, respectively. Multivariate analyses showed that age of ≤35 years, inner quadrant tumor and non-luminal subtype were independent risk factors for LRR and LRFS. Patients with primary tumor in inner quadrant showed higher LRR and poorer LRFS when risk factors are ≥2 than those with tumors in other sites. Conclusions: Inner quadrant tumor was an independent predictor for LRR and LRFS in patients with early breast cancer and one to three positive axillary lymph nodes, which would be more accurate in combination with other prognostic indexes including patients' age, pathological T stage, Ki67 status, molecular subtypes.

An Eighteen-Gene Classifier Predicts Locoregional Recurrence in Post-Mastectomy Breast Cancer Patients

We previously identified 34 genes of interest (GOI) in 2006 to aid the oncologists to determine whether post-mastectomy radiotherapy (PMRT) is indicated for certain patients with breast cancer. At this time, an independent cohort of 135 patients having DNA microarray study available from the primary tumor tissue samples was chosen. Inclusion criteria were 1) mastectomy as the first treatment, 2) pathology stages I-III, 3) any locoregional recurrence (LRR) and 4) no PMRT. After inter-platform data integration of Affymetrix U95 and U133 Plus 2.0 arrays and quantile normalization, in this paper we used 18 of 34 GOI to divide the mastectomy patients into high and low risk groups. The 5-year rate of freedom from LRR in the high-risk group was 30%. In contrast, in the low-risk group it was 99% (p < 0.0001). Multivariate analysis revealed that the 18-gene classifier independently predicts rates of LRR regardless of nodal status or cancer subtype.

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No molecular markers are available to determine post-mastectomy radiotherapy for breast cancer patients.

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Statistically about 2-8% N0 and 20% of N1 mastectomy patients would develop local/regional recurrence (LRR).

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An 18-gene classifier is capable of identifying patients at risk for LRR after mastectomy.

There is no consensus whether to give post-mastectomy radiotherapy to all N1 patients according to the St. Gallen consensus meeting in 2015. Currently about one half of N1 mastectomy patients have been given adjuvant radiotherapy in the United States. From a separate patient population, we now have developed an 18-gene classifier included in our previously published 34-gene panel. This diminished multigene set of classifier is capable of differentiating post-mastectomy breast cancer patients into the low- and high-risk groups. This new classifier has the potential to spare low-risk N1 patients from radiotherapy and at the same time help identify high-risk N0 patients for radiotherapy.

Long-term follow-up for cardiovascular disease after chemotherapy and/or radiotherapy for breast cancer in an unselected population

PURPOSE

Whereas earlier research focused on specific patient groups, this study assessed the risk of cardiovascular disease (CVD) in an unselected population curatively treated for breast cancer (BC), compared with an age-matched random sample of controls.

METHODS

Risks were determined in BC survivors and controls. CVD was divided into three categories: congestive heart failure, vascular cardiac diseases, and "other" cardiac diseases. Hazard ratios (HRs) and 95% confidence intervals (95% CI) adjusted for age, CVD, and CVD risk factors at baseline were determined by Cox regression analyses.

RESULTS

All 561 survivors of BC experienced surgery of whom 229 received (neo)adjuvant radiotherapy, 145 received chemotherapy (with or without radiotherapy), and 187 received no adjuvant therapy. During follow-up (median 9; range 5-57 years), CVD occurred in 176/561 (31%) survivors and in 398/1,635 (24%) controls. After radiotherapy, no increased risks of congestive heart failure (HR 0.5; 95% CI 0.2-1.8), vascular cardiac diseases (HR 1.1; 95% CI 0.7-1.7), or other cardiac diseases (HR 1.3; 95% CI 0.8-2.3) were found compared with controls. Similar results were found after chemotherapy for congestive heart failure (HR 1.8; 95% CI 0.6-5.8), vascular cardiac diseases (HR 1.1; 95% CI 0.5-2.3), and other cardiac diseases (HR 1.2; 95% CI 0.3-5.5).

CONCLUSIONS

In an unselected population of BC survivors, no significant increased risk of CVD after radiotherapy and/or chemotherapy was found compared with controls. However, the HRs after chemotherapy were in-line with previous studies. Future studies should include more detailed information on treatment and more specific outcome measures.

The effects of proton radiation on the prothrombin and partial thromboplastin times of irradiated ferrets

PURPOSE

To determine whether proton radiation affects coagulation.

MATERIAL AND METHODS

Ferrets were exposed to solar particle event-like proton radiation at doses of 0, 25, 100, or 200 centigray (cGy), and dose rates of 50 cGy/minute (high dose rate or HDR) or 50 cGy/hour (low dose rate or LDR). Plasma was isolated from blood collected prior to radiation exposure and at 3-7 h post-radiation. Prothrombin time (PT) assays and activated partial thromboplastin time (aPTT) assays were performed as were mixing studies to determine the coagulation factors involved.

RESULTS

HDR and LDR exposure led to statistically significant increases in PT values. It was determined that the HDR-induced increase in PT was due to Factor VII, while Factors II, V, and VII contributed to the LDR-induced increase in PT values. Only acute LDR exposure caused an increase in aPTT values, which remained elevated for 48 h post-irradiation (which was the latest time assayed in these studies). Mixing studies revealed that Factor IX contributed to the increased aPTT values. A majority of the animals exposed at the LDR had an International Normalized Ratio approaching or surpassing 2.0.

CONCLUSIONS

PT/aPTT assays resulted in increased clotting times due to different coagulation factors, indicating potential radiation-induced coagulopathy.

Radiation-induced morphea of the breast: a case report

Radiation-induced morphea (RIM) of the breast is a rare complication of radiotherapy. It is disfiguring, painful and defeats the purpose of achieving a good cosmesis in breast-conservation surgery. This report describes a severe case of RIM in a breast cancer patient together with photographic illustrations of the serial changes over time and histopathology slides. A review of the literature is provided.