Radiotherapy for initial clinically positive internal mammary nodes in breast cancer

Internal mammary node abnormality in imaging studies and treatment outcomes in patients with breast cancer

The clinical significance of mild internal mammary node (IMN) enlargement (Mild-IMN) is uncertain. This study aimed to evaluate the relationship between treatment outcomes and IMN status in patients with breast cancer who underwent postmastectomy radiation therapy between January 2010 and December 2018. Overall, 250 patients were categorized based on IMN status: Clinically normal IMN (Normal-IMN; n=172), Mild-IMN (n=39) and clinically metastatic IMN (cMet-IMN; n=39). None of the patients in the Normal- or Mild-IMN groups received IMN irradiation. In the cMet-IMN group, 25 patients underwent IMN irradiation with an IMN boost (10 Gy in 5 fractions), while 14 patients did not. The median follow-up time was 80.0 months (range, 7.2-147.6 months). The 7-year overall survival (OS), disease-free survival (DFS) and IMN recurrence-free survival (IRF) rates were 80.2, 73.0 and 93.4%, respectively. Multivariate analyses indicated that only cMet-IMN had a significant impact on OS [hazard ratio (HR), 1.66; 95% CI, 1.01-3.68; P=0.05] and DFS (HR, 1.91; 95% CI, 1.08-3.39; P=0.03), while cMet-IMN did not have a significant impact on IRF (HR, 1.66; 95% CI, 0.41-6.78; P=0.48). Additionally, receiving an IMN boost had no influence on OS (HR, 1.11; 95% CI, 0.37-2.34; P=0.84), DFS (HR, 1.28; 95% CI, 0.51-3.22; P=0.60) or IRF (HR, 1.94; 95% CI, 0.22-17.47; P=0.55). In conclusion, the impact of Mild-IMN on clinical outcomes was small. Although irradiation for cMet-IMN is important, the impact of the cMet-IMN boost with 10 Gy in 5 fractions on clinical outcomes may also be limited.

Quantitative radiomics approach to assess acute radiation dermatitis in breast cancer patients

PURPOSE

We applied a radiomics approach to skin surface images to objectively assess acute radiation dermatitis in patients undergoing radiotherapy for breast cancer.

METHODS

A prospective cohort study of 20 patients was conducted. Skin surface images in normal, polarized, and ultraviolet (UV) modes were acquired using a skin analysis device before starting radiotherapy ('Before RT'), approximately 7 days after the first treatment ('RT D7'), on 'RT D14', and approximately 10 days after the radiotherapy ended ('After RT D10'). Eighteen types of radiomic feature ratios were calculated based on the values acquired 'Before RT'. We measured skin doses in ipsilateral breasts using optically stimulated luminescent dosimeters on the first day of radiotherapy. Clinical evaluation of acute radiation dermatitis was performed using the Radiation Therapy Oncology Group scoring criteria on 'RT D14' and 'After RT D10'. Several statistical analysis methods were used in this study to test the performance of radiomic features as indicators of radiodermatitis evaluation.

RESULTS

As the skin was damaged by radiation, the energy for normal mode and sum variance for polarized and UV modes decreased significantly for ipsilateral breasts, whereas contralateral breasts exhibited a smaller decrease with statistical significance. The radiomic feature ratios at 'RT D7' had strong correlations to skin doses and those at 'RT D14' and 'after RT D10' with statistical significance.

CONCLUSIONS

The energy for normal mode and sum variance for polarized and UV modes demonstrated the potential to evaluate and predict acute radiation, which assists in its appropriate management.

Locoregional breast radiotherapy including IMN: optimizing the dose distribution using an automated non-coplanar VMAT-technique

BACKGROUND

Volumetric Modulated Arc Therapy (VMAT) offers better conformity, homogeneity and sparing of the heart and ipsilateral lung for locoregional radiotherapy in left-sided breast cancer compared to three-dimensional conformal radiotherapy (3D-CRT). However, conventional coplanar VMAT (cVMAT) can result in higher doses to the normal tissue on the contralateral side. This study investigates a non-coplanar VMAT-technique (ncVMAT) to mitigate this issue.

MATERIAL AND METHODS

CT series of 20 left sided breast cancer patients were included for planning of locoregional breast radiotherapy including internal mammary nodes (IMN). Three treatment plans; 3D-CRT, cVMAT and ncVMAT, were generated for each patient with a prescription dose of 40.05 Gy in 15 fractions. Both VMAT-techniques consisted of a single arc in the axial plane, while ncVMAT included an additional arc in the sagittal plane. All plans were optimized to cover the clinical target volume (CTV) by 38.05 Gy for the breast and 36.05 Gy for lymph nodes, with as low as possible dose to organs at risk.

RESULTS

Full CTV coverage was achieved for all plans. Both cVMAT and ncVMAT delivered more conformal and homogeneous target doses than 3D-CRT. Doses to the heart and ipsilateral lung were significantly lower with ncVMAT compared to both cVMAT and 3D-CRT. ncVMAT reduced doses to both the contralateral breast and lung compared to cVMAT and achieved levels similar to 3D-CRT for the contralateral breast and moderately higher doses for the contralateral lung. Delivery of high doses (>30 Gy) to the contralateral side was completely avoided with ncVMAT, contrary to the results for cVMAT and 3D-CRT.

CONCLUSION

ncVMAT reduced doses to the heart and ipsilateral lung as compared to both cVMAT and 3D-CRT. All contralateral dose metrics were reduced with the novel ncVMAT technique compared to cVMAT, and the mean contralateral breast doses were similar to 3D-CRT.

Definitive Radiation With Nodal Boost for Patients With Locally Advanced Breast Cancer

PURPOSE

The optimal local therapy of patients with nodal disease in supraclavicular (SCV), internal mammary nodes (IMN) and level III axilla is not well studied. We aimed to evaluate the outcomes of patients with breast cancer and advanced nodal disease that received a nodal boost.

METHODS AND MATERIALS

This retrospective study included 79 patients with advanced nodal disease who underwent adjuvant radiation with a nodal boost to the SCV, IMNs, and/or axilla. All patients had radiographic changes after systemic therapy concerning for gross nodal disease. Overall survival, disease-free survival (DFS), and local recurrence-free survival were estimated using the Kaplan-Meier method.

RESULTS

All patients received an initial 50 Gy to the breast/chest wall and regional nodes, of whom 46.8% received an IMN boost, 38.0% axillary (ax)/SCV boost, and 15.2% both IMN and ax/SCV boost (IMN + ax/SCV). Most patients had hormone receptor positive (74.7%) and human epidermal growth factor receptor 2 negative disease (83.5%). In addition, 12.7% of patients had clinical (c) N2 disease, 21.5% cN3A disease, 51.9% cN3B disease, and 5.1% cN3C disease. Most patients received chemotherapy (97.5%). The median nodal boost dose was 10 Gy (range, 10-20 Gy), with 21.6% of IMN, 16.7% of ax/SCV, and 16.7% of IMN + ax/SCV receiving 14 to 20 Gy. With a median follow up of 30 months, the 3-year local recurrence-free survival, DFS, and overall survival rates were 94.5%, 86.3%, and 93.8%, respectively. Crude rates of failure were 13.9% (10.1% distant failure [DF] alone; 3.8% DF + locoregional failure [LRF]). Rates of failure by boost group were 13.3% for ax/SCV (10.0% DF alone; 3.3% DF + LRF), 5.4% for IMN (2.7% DF alone, 2.7% DF + LRF), and 41.7% for IMN + ax/SCV (33.3% DF, 8.3% DF + LRF). There were no LRFs without DFs. The median time to failure was 22.8 months (interquartile range, 18-34 months). Clinical tumor size and IMN + ax/SCV versus IMN or ax/SCV alone was associated with worse DFS (hazard ratio [HR]: 9.78; 95% confidence interval [CI], 2.07-46.2; P = .004 and HR: 9.49; 95% CI, 2.67-33.7; P = .001, respectively). On multivariate analysis, IMN + ax/SCV versus IMN or ax/SCV alone retained significance (HR: 4.80; 95% CI, 1.27-18.13; P = .02).

CONCLUSIONS

In this population of patients with locally advanced breast cancer, the majority of failures were distant with no isolated LRFs. Failures were the highest in the IMN + ax/SCV group (∼40%). Further treatment escalation is necessary for these patients.

Evaluation of the dosimetric and radiobiological parameters in four radiotherapy regimens for synchronous bilateral breast cancer

This study is to investigate the optimal treatment option for synchronous bilateral breast cancer (SBBC) by comparing dosimetric and radiobiological parameters of intensity‐modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) plans using single and dual isocenters.

Twenty patients with SBBC without lymph node involvement were selected retrospectively. Four treatment plans were generated for each patient using the Eclipse treatment planning system (Varian Medical System, Palo Alto, CA, USA) following two delivery techniques with two isocenter conditions—IMRT using a single isocenter (IMRT_Iso1), VMAT using a single isocenter (VMAT_Iso1), IMRT using dual isocenters (IMRT_Iso2), and VMAT using dual isocenters (VMAT_Iso2). A dose of 42.56 Gy in 16 fractions was prescribed for the planning target volume (PTV). All plans were calculated using the Acuros XB algorithm and a photon optimizer for a 6‐MV beam of a Vital Beam linear accelerator. PTV‐related dosimetric parameters were analyzed. Further, the homogeneity index, conformity index, and conformation number were computed to evaluate plan quality. Dosimetric parameters were also measured for the organs at risk (OARs). In addition, the equivalent uniform dose corresponding to an equivalent dose related to a reference of 2 Gy per fraction, the tumor control probability, and the normal tissue complication probability were calculated based on the dose–volume histogram to investigate the radiobiological impact on PTV and OARs.

IMRT_Iso1 exhibited similar target coverage and a certain degree of dosimetric improvement in OAR sparing compared to the other techniques. It also exhibited some radiobiological improvement, albeit insignificant. Although IMRT_Iso1 significantly increased monitor unit compared to VMAT_Iso1, which is the best option in terms of delivery efficiency, there was only a 22% increase in delivery time. Therefore, in conclusion, IMRT_Iso1, the complete treatment of which can be completed using a single setup, is the most effective method for treating SBBC.

Clinical audit of breast cancer patients treated with helical tomotherapy for irradiation of the internal mammary chain

Aim:

To evaluate efficacy of helical tomotherapy (HT) for treatment of breast cancer with internal mammary lymph node involvement.

Methods:

This is a retrospective clinical audit of planning, dosimetry, toxicity and short-term survival of a cohort of 65 patients. Patients were treated between November 2014 and May 2019. The primary and nodal region was prescribed a dose of 50 Gray (Gy) in 25 fractions, while all cases of breast conserving surgery received a simultaneous integrated boost to a dose of 61 Gy in 25 fractions.

Results:

The 95% coverage for the primary, supraclavicular, internal mammary node and tumour bed was 93·4%, 96·8%, 90·7% and 98·3%, respectively. Mean dose to total lung, heart and contra-lateral breast was 10·6 Gy, 6·92 Gy and 4·32 Gy, respectively. None developed grade III skin or oesophageal toxicity. Twenty-one patients had progression; of which eighteen developed only distant failure while three also had loco-regional recurrence. At a median follow-up of 36 months, the 3-year loco-regional control, disease-free survival and overall survival were 93·5, 73·9 and 85·9%, respectively.

Conclusion:

We report encouraging clinical outcome for patients treated uniformly with HT. The predominant pattern of failure was distant metastases which suggests the need for systemic control intensification.

Outcome of radiotherapy for clinically overt metastasis to the internal mammary lymph node in patients receiving neoadjuvant chemotherapy and breast cancer surgery

PURPOSE

This study was aimed to assess the outcome of radiotherapy and determine prognostic factors for survival in breast cancer patients with clinically overt metastasis to the internal mammary lymph node (IMN+).

METHODS

We retrospectively reviewed the medical records of 193 patients with IMN + breast cancer who received neoadjuvant chemotherapy (NAC), breast surgery without internal mammary lymph node (IMN) dissection, and postoperative radiotherapy at 9 hospitals between 2009 and 2013. Breast-conserving surgery or mastectomy was performed after taxane-based NAC. Radiotherapy was administered to the whole breast/chest wall and regional nodes. IMN-covering radiotherapy was performed in 92.2% of patients with median dose of 58.4 Gy (range, 44.9-69.1 Gy). The overall survival (OS), disease-free survival (DFS), and IMN failure-free survival (IMNFFS) were analyzed.

RESULTS

After median follow-up of 71 months, 9 patients (4.7%) developed IMN failure and simultaneous distant metastasis. The 5-year DFS, OS, and IMNFFS was 68.6%, 81.8%, and 95.3%, respectively. Non-triple-negative breast cancer, Ki-67 ≤ 10%, pathological complete response (CR) in tumor and axillary node, and radiologic CR of IMN after NAC were significant factors for predicting higher DFS; however, IMN radiation dose was not significant determinants for DFS. The 5-year DFS of patients with IMN-dose ≤ 50.0 Gy and those with >50.0 Gy was 86.7% and 76.7%, respectively (p = 0.41).

CONCLUSIONS

A multimodality strategy including NAC, breast surgery, and IMN-covering radiotherapy was effective for patients with overt IMN + breast cancer. Even without an IMN dissection, most patients were IMN failure-free with an IMN-focusing radiotherapy.

Development of an Individualized Prediction Calculator for the Benefit of Postoperative Radiotherapy in Patients with Surgically Resected De Novo Stage IV Breast Cancer

PURPOSE

Locoregional treatment has been increasingly adopted for metastatic breast cancer at presentation. This study aims to develop an individualized calculator to predict the benefit of postoperative radiotherapy (PORT) for patients with surgically resected de novo stage IV breast cancer.

METHODS AND MATERIALS

We searched the Surveillance, Epidemiology, and End Results (SEER) database for patients diagnosed with stage IV breast cancer between 2010 and 2014. After applying exclusion criteria, a total of 4473 patients were included in the analysis. Propensity score matching was used to balance the individual characteristics of the patients. After identifying the significant prognosticators, a nomogram was developed using multivariate regression models and internally validated. A web-based calculator was then constructed using a fitted survival prediction model.

RESULTS

With a median follow-up of 34 months, the three-year overall survival (OS) rates were 54.1% in the surgery alone group and 63.5% in the surgery + PORT group (p < 0.001). The survival benefit of PORT was maintained after propensity score matching (p < 0.001). Interaction testing of the prognostic variables found significant interactions between PORT and the presence of brain metastasis (p = 0.001), and between PORT and hormonal receptor expression (p = 0.018). After reviewing the performance of various models, a log-normal distributed survival model was adopted, with a C-index of 0.695. A calibration plot verified that the predicted survival rates were strongly correlated with the actual OS rates. A web-based survival calculator was constructed to provide individualized estimates of survival according to PORT.

CONCLUSION

PORT significantly improved OS rates, though the individual benefit was affected by a number of factors. We successfully developed a nomogram and web-based calculator that predicted the prognosis according to PORT in patients with surgically resected de novo stage IV breast cancer. These tools are expected to be useful in clinical practice and in the design of related trials.

Coronary Event Analysis in Breast Cancer Patients Who Received Breast-Conserving Surgery and Post-Operative Radiotherapy: a Korean Nationwide Cohort Study

Purpose

Adjuvant breast radiotherapy (RT) following breast-conserving surgery (BCS) has been reported to induce cardiac toxicity in breast cancer patients. We investigated the incidence and risk factors of major coronary events after breast RT using Korean nationwide Health Insurance Review and Assessment data.

Methods

Using data from a nationwide quality assessment of breast cancer treatment, we identified 3,251 patients who received breast RT after BCS in 2013. Data about major coronary events were additionally collected from national claims data. We defined major coronary events according to the International Classification of Diseases, 10th revision (ICD-10) codes I20-25.

Results

A total of 172 major coronary events (5.3%) occurred among 3,251 breast cancer patients. The 1-year, 2-year, and 3-year coronary event-free survival rates were 98.1%, 96.4% and 95.2%, respectively. Patients with underlying diabetes mellitus (88.6% vs. 95.7%, p < 0.001), high blood pressure (HBP) (89.4% vs. 96.3%, p < 0.001), and cerebrovascular accident (CVA) (84.0% vs. 95.4%, p < 0.001) showed significantly worse 3-year coronary event-free survival rates than those without comorbidities. Multivariate analysis revealed that patient age (p < 0.001), HBP (p < 0.001), CVA (p = 0.025), adjuvant hormonal therapy (p = 0.034), and Herceptin therapy (p < 0.001) were significantly associated with major coronary events in breast cancer patients.

Conclusion

The incidence of major coronary events after breast RT may be higher in breast-cancer patients with risk factors such as underlying HBP or CVA, or who were in receipt of adjuvant Herceptin therapy. Heart-sparing RT techniques or intensity-modulated RT should be considered for breast-cancer patients with risk factors for heart toxicity.

Optimal radiotherapy for patients with internal mammary lymph node metastasis from breast cancer

Background

This study aimed to determine the optimal radiotherapy (RT) regimen for patients with clinical metastasis to the internal mammary lymph node (cIMN+) from breast cancer.

Methods

We retrospectively reviewed the medical records of 84 patients with cIMN+ breast cancer treated with curative surgery, taxane-based chemotherapy, and postoperative RT between January 2009 and December 2014. Postoperative RT was administered to the whole breast or chest wall using 50 Gy in 2 Gy fractions. Boost RT to the internal mammary lymph node (IMN) was administered at the physician’s discretion. We categorized patients into two groups according to the IMN dose as follows: low-dose IMN RT (50.0–63.5 Gy) and high-dose IMN RT (63.6–70.4 Gy).

Results

After a median follow-up of 58 months (range, 12–111 months), IMN recurrence was observed in 2 patients (2.4%), and all IMN recurrences developed simultaneously with distant metastases. The 5-year locoregional recurrence-free survival, disease-free survival (DFS), and overall survival rates were 89.1, 72.0, and 81.2%, respectively. The triple-negative subtype, IMN size ≥1.0 cm, old age, and low-dose IMN were significantly associated with poor DFS. Among the patients with IMN size ≥1.0 cm, the 5-year DFS was significantly higher in those treated with high-dose IMN RT than in those treated with low-dose IMN RT (69.3% vs. 33.3%, p = 0.019).

Conclusions

IMN RT without IMN dissection resulted in favorable outcomes in cIMN+ breast cancer. For patients with a large IMN, a higher IMN radiation dose might be needed for disease control.

Adjuvant regional nodal irradiation did not improve outcomes in T1-2N1 breast cancer after breast-conserving surgery: A propensity score matching analysis of BIG02/98 and BCIRG005 trials

Aim

To determine whether the addition of regional nodal irradiation (RNI) to whole-breast irradiation (WBI) would improve outcomes over WBI alone in T1-2N1 breast cancer after breast-conserving surgery (BCS) and adjuvant systematic therapy.

Methods

Data were obtained from two randomized controlled trials (NCT00174655 and NCT00312208). Univariate and multivariate Cox-regression analysis were performed to investigate predictors for overall survival and disease-free survival. A 1:1 propensity score matching (PSM) analysis was applied to eliminate selection bias.

Results

With median follow-up 80 months (range: 3–155 months), the 5-year local regional recurrence in the WBI group was 2% vs. 5% (p = 0.28) in the WBI + supraclavicular radiotherapy, and the rate of 5-year distant metastasis in the WBI group was 7% vs. 13% in the WBI + supraclavicular radiotherapy (p = 0.0748); In addition, the 5-year local regional recurrence in the WBI group was 3% vs. 9% (p = 0.19) in the WBI + internal mammary irradiation (IMI); However, the rate of 5-year distant metastasis in the in the WBI group was significantly lower than that in the WBI + IMI (8% vs. 24%, p = 0.036). After PSM, cox-regression analysis indicated that neither RNI nor IMI in combination with WBI in T1-2N1 breast cancer was associated with an improved overall survival and disease-free survival when compared to WBI alone.

Conclusion

The addition of RNI to WBI in T1-2N1 breast cancer after BCS and adjuvant systematic therapy did not improve outcomes in comparison with WBI alone. Further studies are still needed to identify patients who would most benefit from RNI in this patient population.

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The addition of RNI to WBI in unselected T1-2N1 breast cancer after BCS and adjuvant systematic therapy does not significantly improve outcomes in comparison with WBI alone.

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Early stage (pT1-2N1) breast cancer after BCS represents a diverse population.

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An individualized risk analysis based on clinical-genomic models is recommended to identify patients who would benefits or omit from RNI in further prospective studies.