Determining the Organ at Risk for Lymphedema After Regional Nodal Irradiation in Breast Cancer

Patient-Reported Outcomes Between Whole-Breast Plus Regional Irradiation and Whole-Breast Irradiation Only in pN1 Breast Cancer After Breast-Conserving Surgery and Taxane-Based Chemotherapy: A Randomized Phase 3 Clinical Trial (KROG 17-01)

PURPOSE

The role of regional node irradiation (RNI) with whole-breast irradiation (WBI) in patients with pN1 breast cancer receiving taxane-based adjuvant chemotherapy is not well defined. The KROG 1701 trial, a phase 3, multicenter, noninferiority study, aimed to compare the disease-free survival between WBI+RNI and WBI alone in this patient cohort. Comprehensive patient-reported outcomes (PROs) collected at multiple timepoints are reported.

METHODS AND MATERIALS

The trial (NCT03269981) enrolled patients with pN1 breast cancer after breast-conserving surgery and taxane-based adjuvant chemotherapy, allocating them to receive either WBI+RNI or WBI only. PROs were assessed using European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaires Core 30and breast cancer-specific module 23 modules at baseline, during radiation therapy, and at subsequent follow-up intervals of 3 to 6 months, and annually up to 4 years.

RESULTS

From April 2017 to December 2021, 840 patients were enrolled; 777 received intervention as assigned, and 750 completed baseline PRO questionnaires (387 in WBI+RNI, 363 in WBI only). All PRO domains showed improvements over time (P < .001). During radiation therapy, the WBI+RNI group reported greater fatigue and nausea. Higher arm symptom scores were observed in the WBI+RNI group 3 months post-treatment (P = .030). No other significant PRO domain differences, including arm/breast symptoms, were observed between the 2 groups.

CONCLUSIONS

In patients with pN1 breast cancer treated with taxane-based chemotherapy, adding RNI to WBI resulted in minor, temporary declines in specific PRO domains, but these differences were not clinically significant. This indicates that overall patient experience between WBI+RNI and WBI is comparable, supporting the safety and patient tolerability of both treatments.

A systematic review and meta-analysis of risk factors influencing patient-reported arm symptoms post-breast cancer treatment: Accounting for radiotherapy impact

OBJECTIVES

To systematically review risk factors for patient-reported arm symptoms (AS) in breast cancer (BC), considering radiotherapy (RT) impact, using the EORTC QLQ-BR23 questionnaire (BR23).

METHODS

PubMed, Embase, Cochrane Library, MEDLINE, and Web of Science were searched using the keywords "breast neoplasms", "radiotherapy", and "BR23" up to March 5th, 2024.

INCLUSION CRITERIA

both univariate and multivariate analyses.

EXCLUSION CRITERIA

pregnancy, recurrence, distant metastasis BC, reirradiation, or lack of RT. The risk of bias of included papers was assessed using the Critical Appraisal Skills Program (CASP) checklist. Descriptive and meta-analyses were conducted using risk ratio (RR) or standardized mean difference (SMD) with 95 % confidence intervals (CI) as effect measures. A random-effects model was applied if I2 > 50 %.

RESULTS

Eighteen out of 734 studies were included, with sample sizes ranging from 172 to 2208. Commonly reported risk factors included axillary lymph node dissection (ALND), mastectomy, chemotherapy (CT), and RT (6, 5, 4, and 4 studies, respectively). In meta-analyses, ALND was a risk factor for arm pain (RR [95 % CI] = 1.75 [1.14; 2.71]), lymphedema (RR [95 % CI] = 5.41 [3.48; 8.39]), and overall AS (SMD [95 % CI] = 0.49 [0.14; 0.83]) compared to sentinel lymph node biopsy. RT was not a risk factor, but axillary RT significantly increased overall AS (SMD [95 % CI] = 0.55 [0.40; 0.70]) compared to no axillary RT.

CONCLUSION

ALND and mastectomy were the primary risk factors for patient-reported AS. Axillary RT was a significant risk factor, whereas general RT was not.

Clinical, Pathologic, and Dosimetric Predictors of Head and Neck Lymphedema Following Definitive or Adjuvant Radiation Therapy for Head and Neck Cancer

Purpose

Head and neck lymphedema (HNL) following radiation therapy for head and neck cancer (HNC) causes patient morbidity. Predicting individual patients' risk of HNL after treatment is challenging. We aimed to identify the demographic, disease-related, and treatment-related factors associated with external and internal HNL following treatment of HNC with definitive or adjuvant radiation therapy.

Methods and Materials

Relevant clinical, pathologic, and dosimetric data for 76 consecutive patients who received definitive or adjuvant radiation ± chemotherapy were retrospectively collected from a single institution. Multivariable models predictive of external and internal lymphedema using clinicopathologic variables alone and in combination with dosimetric variables were constructed and optimized using competing risk regression.

Results

After median follow-up of 550 days, the incidence of external and internal HNL at 360 days was 70% and 34%, respectively. When evaluating clinical and treatment-related factors alone, number of lymph nodes removed and advanced adenopathy status were predictive of external lymphedema. With incorporation of dosimetric variables, the optimized model included the percentage volume of the contralateral lymph node level VII receiving 30Gy V30 ≥50%, number of lymph nodes removed, and advanced adenopathy status. For internal lymphedema, our clinicopathologic model identified both adjuvant radiation, as opposed to definitive radiation, and advanced adenopathy status. With inclusion of a dosimetric variable, the optimized model included larynx V45 ≥50% and advanced adenopathy.

Conclusions

HNL following HNC treatment is common. For both external and internal lymphedema, nodal disease burden at diagnosis predicts increased risk. For external lymphedema, increasing extent of lymph node dissection prior to adjuvant therapy increases risk. The contralateral level VII lymph node region is also predictive of external lymphedema when radiation dose to V30 is ≥50%, meriting investigation. For internal lymphedema, we confirm that increasing radiation dose to the larynx is the most significant dosimetric predictor of mucosal edema when larynx V45 is ≥50%.

Determining risk and predictors of head and neck cancer treatment-related lymphedema: A clinicopathologic and dosimetric data mining approach using interpretable machine learning and ensemble feature selection

Background and purpose

The ability to determine the risk and predictors of lymphedema is vital in improving the quality of life for head and neck (HN) cancer patients. However, selecting robust features is challenging due to the multicollinearity and high dimensionality of radiotherapy (RT) data. This study aims to overcome these challenges using an ensemble feature selection technique with machine learning (ML).

Materials and methods

Thirty organs-at-risk, including bilateral cervical lymph node levels, were contoured, and dose-volume data were extracted from 76 HN treatment plans. Clinicopathologic data was collected. Ensemble feature selection was used to reduce the number of features. Using the reduced features as input to ML and competing risk models, internal and external lymphedema prediction capability was evaluated with the ML models, and time to lymphedema event and risk stratification were estimated using the risk models.

Results

Two ML models, XGBoost and random forest, exhibited robust prediction performance. They achieved average F1-scores and AUCs of 84 ± 3.3 % and 79 ± 11.9 % (external lymphedema), and 64 ± 12 % and 78 ± 7.9 % (internal lymphedema). Predictive ML and risk models identified common predictors, including bulky node involvement, high dose to various lymph node levels, and lymph nodes removed during surgery. At 180 days, removing 0-25, 26-50, and > 50 lymph nodes increased external lymphedema risk to 72.1 %, 95.6 %, and 57.7 % respectively (p = 0.01).

Conclusion

Our approach, involving the reduction of HN RT data dimensionality, resulted in effective ML models for HN lymphedema prediction. Predictive dosimetric features emerged from both predictive and competing risk models. Consistency with clinicopathologic features from other studies supports our methodology.

Multinational Association of Supportive Care in Cancer (MASCC) clinical practice guidance for the prevention of breast cancer-related arm lymphoedema (BCRAL): international Delphi consensus-based recommendations

Background

Developing strategies to prevent breast cancer-related arm lymphoedema (BCRAL) is a critical unmet need because there are no effective interventions to eradicate it once it reaches a chronic state. Certain strategies such as prospective surveillance programs and prophylactic lymphatic reconstruction have been reported to be effective in clinical trials. However, a large variation exists in practice based on clinician preference, organizational standards, and local resources.

Methods

A two-round international Delphi consensus process was performed from February 27, 2023 to May 25, 2023 to compile opinions of 55 experts involved in the care and research of breast cancer and lymphoedema on such interventions.

Findings

Axillary lymph node dissection, use of post-operative radiotherapy, relative within-arm volume increase one month after surgery, greater number of lymph nodes dissected, and high body mass index were recommended as the most important risk factors to guide selection of patients for interventions to prevent BCRAL. The panel recommended that prospective surveillance programs should be implemented to screen for and reduce risks of BCRAL where feasible and resources allow. Prophylactic compression sleeves, axillary reverse mapping and prophylactic lymphatic reconstruction should be offered for patients who are at risk for developing BCRAL as options where expertise is available and resources allow. Recommendations on axillary management in clinical T1-2, node negative breast cancer patients with 1-2 positive sentinel lymph nodes were also provided by the expert panel. Routine axillary lymph node dissection should not be offered in these patients who receive breast conservation therapy. Axillary radiation instead of axillary lymph node dissection should be considered in the same group of patients undergoing mastectomy.

Interpretation

An individualised approach based on patients' preferences, risk factors for BCRAL, availability of treatment options and expertise of the healthcare team is paramount to ensure patients at risk receive preventive interventions for BCRAL, regardless of where they are receiving care.

Funding

This study was not supported by any funding. RJC received investigator grant support from the Australian National Health and Medical Research Council (APP1194051).

Incidence of and Influencing Factors for Arm Lymphedema After Salvage Treatment for an Isolated Locoregional Recurrence of Breast Cancer

PURPOSE

Data on subsequent arm lymphedema (SAL) after salvage treatment for locoregional recurrence (LRR) of breast cancer are limited. We conducted a study to evaluate the risk of SAL in patients with LRR.

METHODS

We reviewed the data of patients with breast cancer who had LRR and were initially diagnosed between January 2003 and December 2017. Among the 214 patients who received curative salvage treatment, most had local (n = 125, 57.9%), followed by regional (n = 73, 34.1%), and locoregional (n = 16, 7.9%) recurrences. A competing risk analysis considering the factors of death and a second LRR were performed to exclude potential malignant lymphedema. We used the Fine-Gray subdistribution hazards model to estimate the hazard ratio (HR) for comparing the risk of SAL.

RESULTS

With a median follow-up duration of 41.4 months (interquartile range, 25.6-65.1), 51 patients (23.8%) experienced SAL with a median interval of 9.9 months after treatment. The two-year cumulative incidence of SAL was 12.7%. Among the 18 patients with initial lymphedema, nine (50.0%) developed SAL. Multivariate analysis revealed that a history of lymphedema (HR, 4.61; p < 0.001) and taxane-based salvage chemotherapy (HR, 2.38; p = 0.009) were significantly associated with SAL development.

CONCLUSION

Salvage treatment for LRR-induced SAL was performed in 24% of the patients. A history of initial lymphedema and salvage taxane-based chemotherapy increases the risk of developing SAL. Therefore, close surveillance for the incidence of SAL is required in patients opting for salvage treatment for LRR.

The Axillary Lateral Vessel Thoracic Junction Is Not an Organ at Risk for Breast Cancer-Related Lymphedema

PURPOSE

Breast cancer-related lymphedema (BCRL) is a treatment complication that significantly reduces patient quality of life. Regional nodal irradiation (RNI) may increase the risk of BCRL. Recently, a region of the axilla known as the axillary-lateral thoracic vessel juncture (ALTJ) was identified as a potential organ at risk (OAR). Here, we set out to validate whether radiation dose to the ALTJ is associated with BCRL.

METHODS AND MATERIALS

We identified patients with stage II-III breast cancer treated with adjuvant RNI from 2013 to 2018, excluding those with BCRL preradiation. We defined BCRL as difference in arm circumference between the ipsilateral and contralateral limb >2.5 cm at any 1 encounter or ≥2 cm on ≥2 visits. All patients suspected of having BCRL at routine follow-up visits were referred to physical therapy for confirmation. The ALTJ was retrospectively contoured and dose metrics were collected. Cox proportional hazards regression models were used to test the association between clinical and dosimetric parameters with the development of BCRL.

RESULTS

The study population included 378 patients with a median age of 53 years, median body mass index of 28.4 kg/m2, and median of 18 axillary nodes removed; 71% underwent mastectomy. Median follow-up was 70 months (interquartile range, 55-89.7 months). BCRL developed in 101 patients at a median of 18.9 months (interquartile range, 9.9-32.4 months), with a corresponding 5-year cumulative incidence BCRL of 25.8%. On multivariate analysis, none of the ALTJ metrics were associated with BCRL risk. Only increasing age, increasing body mass index, and increasing number of nodes were associated with a higher risk of developing BCRL. The 6-year locoregional recurrence rate was 3.2%, the axillary recurrence rate was 1.7%, and the isolated axillary recurrence rate was 0%.

CONCLUSIONS

The ALTJ is not validated as a critical OAR for reducing BCRL risk. Until such an OAR is discovered, the axillary PTV should not be modified or dose reduced in efforts to reduce BCRL.

Incorporating axillary-lateral thoracic vessel juncture dosimetric variables improves model for predicting lymphedema in patients with breast cancer: A validation analysis

Background

A relationship between the axillary-lateral thoracic vessel juncture (ALTJ) dose and lymphedema rate has been reported in patients with breast cancer. The purpose of this study was to validate this relationship and explore whether incorporation of the ALTJ dose-distribution parameters improves the prediction model's accuracy.

Methods

A total of 1,449 women with breast cancer who were treated with multimodal therapies from two institutions were analyzed. We categorized regional nodal irradiation (RNI) as limited RNI, which excluded level I/II, vs extensive RNI, which included level I/II. The ALTJ was delineated retrospectively, and dosimetric and clinical parameters were analyzed to determine the accuracy of predicting the development of lymphedema. Decision tree and random forest algorithms were used to construct the prediction models of the obtained dataset. We used Harrell's C-index to assess discrimination.

Results

The median follow-up time was 77.3 months, and the 5-year lymphedema rate was 6.8 %. According to the decision tree analysis, the lowest lymphedema rate (5-year, 1.2 %) was observed in patients with ≤ six removed lymph nodes and ≤ 66 % ALTJ V_35Gy. The highest lymphedema rate was observed in patients with > 15 removed lymph nodes and an ALTJ maximum dose (D_max) of > 53 Gy (5-year, 71.4 %). Patients with > 15 removed lymph nodes and an ALTJ D_max ≤ 53 Gy had the second highest rate (5-year, 21.5 %). All other patients had relatively minor differences, with a rate of 9.5 % at 5 years. Random forest analysis revealed that the model's C-index increased from 0.84 to 0.90 if dosimetric parameters were included instead of RNI (P <.001).

Conclusion

The prognostic value of ALTJ for lymphedema was externally validated. The estimation of lymphedema risk based on individual dose-distribution parameters of the ALTJ seemed more reliable than that based on the conventional RNI field design.

Incidental Axillary Dose of Tomotherapy in Hypofractionated Whole Breast Radiotherapy for Early Breast Cancer: A Dosimetrical Analysis

Background and Objectives: Intensity-modulated radiation therapy (IMRT) is becoming a more common method of performing whole breast irradiation (WBI) for early breast cancer. This study aimed to examine the incidental dose to the axillary region using tomotherapy, a unique form of IMRT. Patients and Methods: This study included 30 patients with early-stage breast cancer who underwent adjuvant WBI using TomoDirect IMRT. A hypofractionation scheme of 42.4 Gy delivered in 16 fractions was prescribed. The plan comprised of two parallel-opposed beams, along with two additional beams positioned anteriorly at gantry angles of 20° and 40° from the medial beam. The incidental dose received at axillary levels I, II, and III was evaluated using several dose-volume parameters. Results: The study participants had a median age of 51 years, and 60% had left-sided breast cancer. The mean dose of the axilla for levels I, II, and III were 15.5 ± 4.8 Gy, 14.9 ± 4.2 Gy, and 1.5 ± 1.6 Gy, respectively. Adequate coverage of the axilla, defined as V95%[%], was achieved for 4.7 ± 3.9%, 4.8 ± 3.7%, and 0 ± 0% for levels I, II, and III, respectively. The results were compared with those of previously published studies, and the axillary mean dose and V95%[%] of TomoDirect IMRT were low, comparable to other IMRT techniques, and lower than those of traditional tangential therapy. Conclusions: While incidental axillary radiation during WBI has been proposed to assist in regional disease control, the TomoDirect plan was demonstrated to decrease this dose, and a hypofractionation scheme would further lower its biological effectiveness. Future clinical studies should incorporate dosimetrical analysis of incidental axillary dose, in order to facilitate hypofractionated IMRT planning with risk-adjusted axilla coverage in early breast cancer.

Development and Validation of a Normal Tissue Complication Probability Model for Lymphedema After Radiation Therapy in Breast Cancer

PURPOSE

To develop and test a multivariable normal tissue complication probability (NTCP) model predicting lymphedema in patients with breast cancer receiving radiation therapy.

METHODS AND MATERIALS

We retrospectively reviewed 1345 patients with breast cancer who received radiation therapy from 2 independent institutions. The patients were divided into a training cohort (institution A, n = 368, all treated with 3-dimensional conformal external beam radiation therapy [RT] with 2 Gy/fraction) and an external validation cohort (institution B, n = 977, treated either with 3-dimensional conformal external beam RT or with volumetric modulated RT and either with 1.8-2.0 Gy/fraction or with 2.67 Gy/fraction). Axillary-lateral thoracic vessel juncture (ALTJ) was delineated. The multivariable model was generated using dosimetric and clinical parameters. The performance of the model was comprehensively validated internally and externally.

RESULTS

During a median follow-up of 78.7 months for the entire cohort, 97 patients (7.2%) developed lymphedema. The multivariable model that took into account the number of lymph nodes dissected, as well as the volume of the ALTJ receiving a dose ≥35 Gy equivalent doses in 2-Gy fractions (ALTJ V35), showed good agreement between predicted and observed results for both internal and external validation (Hosmer-Lemeshow P value > .05). The area under the receiver operating characteristic curve (AUC) and negative log-likelihood values for the multivariable NTCP model were 0.89 and 0.19 in internal validation and 0.83 and 0.19 in external validation. In addition, the multivariable model performance was acceptable for hypofractionated regimens (AUC 0.70) and volumetric modulated arc therapy (AUC 0.69). The number of lymph nodes dissected and ALTJ V35 were found to be the most important factors influencing lymphedema after radiation therapy.

CONCLUSIONS

We first developed and validated the multivariable NTCP model for the lymphedema incidence in patients with breast cancer after radiation therapy. The multivariable NTCP model showed excellent performance and robustness in predicting lymphedema in both internal and completely independent external validations. The multivariable model for lymphedema prediction was robust and reliable for different treatment modalities and fractionation regimens.

Patterns of regional recurrence according to molecular subtype in patients with pN2 breast cancer treated with limited field regional irradiation

OBJECTIVE

There is little evidence regarding the radiotherapy modification based on molecular subtypes in breast cancer. This study aimed to identify the risk and patterns of regional recurrence according to molecular subtype in patients with pN2 breast cancer.

METHODS

We identified 454 patients who underwent radical surgery for breast cancer with 4-9 axillary lymph node metastases. All patients underwent axillary lymph node dissection, adjuvant chemotherapy and limited-field regional nodal irradiation. The rates and patterns of regional recurrence were compared between the following three subgroups: luminal type (estrogen receptor- and/or progesterone receptor-positive), HER2-type (estrogen receptor- and progesterone receptor-negative and HER2-positive) and triple-negative type (estrogen receptor-, progesterone receptor- and HER2-negative).

RESULTS

Regional recurrence occurred in 18/454 patients (4%). The risk of regional recurrence was higher in the triple-negative (hazard ratio 7.641) and HER2-type (hazard ratio 4.032) subtypes than in the luminal subtype. The predominant pattern of regional recurrence was inside the radiotherapy field in triple-negative breast cancer and outside the radiotherapy field in HER2-type and luminal-type cancers.

CONCLUSIONS

In patients with pN2 breast cancer, the risk of regional recurrence was higher in the triple-negative and HER2-type than in the luminal type. In-field recurrence was predominant in triple-negative cancer, while out-field recurrence was frequent in luminal and HER2-type breast cancers.

Risk factors of unilateral breast cancer-related lymphedema: an updated systematic review and meta-analysis of 84 cohort studies

PURPOSE

To review and update the incidence and risk factors for breast cancer-related lymphedema based on cohort studies.

METHODS

The study was guided by the Joanna Briggs Institute methodology and the Cochrane handbook for systematic reviews. PubMed, EMBASE, CINAHL, Scopus, Web of Science, The Cochrane Library, CNKI, SinoMed, and Wan Fang Database were searched from inception to November 15, 2021. Cohort studies reported adjusted risk factors were selected. PRISMA guideline was followed. Study quality were evaluated using the Newcastle-Ottawa scale. Random-effects models were adopted. The robustness of pooled estimates was validated by meta-regression and subgroup analysis. Lymphedema incidence and adjusted risk factors in the multivariable analyses with hazard / odds ratios and 95% CIs were recorded.

RESULTS

Eighty-four cohort studies involving 58,358 breast cancer patients were included. The pooled incidence of lymphedema was 21.9% (95% CI, 19.8-24.0%). Fourteen factors were identified including ethnicity (black vs. white), higher body mass index, higher weight increase, hypertension, higher cancer stage (III vs. I-II), larger tumor size, mastectomy (vs. breast conservation surgery), axillary lymph nodes dissection, more lymph nodes dissected, higher level of lymph nodes dissection, chemotherapy, radiotherapy, surgery complications, and higher relative volume increase postoperatively. Additionally, breast reconstruction surgery, and adequate finance were found to play a protective role. However, other variables such as age, number of positive lymph nodes, and exercise were not correlated with risk of lymphedema.

CONCLUSION

Treatment-related factors still leading the development of breast cancer-related lymphedema. Other factors such as postoperative weight increase and finance status also play a part. Our findings suggest the need to shift the focus from treatment-related factors to modifiable psycho-social-behavioral factors.

Prediction of breast cancer-related lymphedema risk after postoperative radiotherapy via multivariable logistic regression analysis

PURPOSE

We identified novel clinical and dosimetric prognostic factors affecting breast cancer-related lymphedema after postoperative radiotherapy (RT) and developed a multivariable logistic regression model to predict lymphedema in these patients.

METHODS AND MATERIALS

In total, 580 patients with unilateral breast cancer were retrospectively reviewed. All patients underwent breast surgery and postoperative RT with or without systemic treatment in 2015. Among the 580 patients, 532 with available RT plan data were randomly divided into training (n=372) and test (n=160) cohorts at a 7:3 ratio to generate and validate the lymphedema prediction models, respectively. An area under the curve (AUC) value was estimated to compare models.

RESULTS

The median follow-up duration was 5.4 years. In total, 104 (17.9%) patients experienced lymphedema with a cumulative incidence as follows: 1 year, 10.5%; 3 years, 16.4%; and 5 years, 17.6%. Multivariate analysis showed that body mass index ≥25 kg/m2 (hazard ratio [HR] 1.845), dissected lymph nodes ≥7 (HR 1.789), and taxane-base chemotherapy (HR 4.200) were significantly associated with increased lymphedema risk. Conversely, receipt of RT at least 1 month after surgery reduced the risk of lymphedema (HR 0.638). A multivariable logistic regression model using the above factors, as well as the minimum dose of axillary level I and supraclavicular lymph node, was created with an AUC of 0.761 and 0.794 in the training and test cohorts, respectively.

CONCLUSIONS

Our study demonstrated that a shorter interval from surgery to RT and other established clinical factors were associated with increased lymphedema risk. By combining these factors with two dosimetric parameters, we propose a multivariable logistic regression model for breast cancer-related lymphedema prediction after RT.

Preoperative and postoperative nomograms for predicting early recurrence of hepatocellular carcinoma without macrovascular invasion after curative resection

BACKGROUND

Postoperative early recurrence (ER) is a major obstacle to long-term survival after curative liver resection (LR) in patients with hepatocellular carcinoma (HCC). This study aimed to establish preoperative and postoperative nomograms to predict ER in HCC without macrovascular invasion.

METHODS

Patients who underwent curative LR for HCC between January 2012 and December 2016 were divided into training and internal prospective validation cohorts. Nomograms were constructed based on independent risk factors derived from the multivariate logistic regression analyses in the training cohort. The predictive performances of the nomograms were validated using the internal prospective validation cohort.

RESULTS

In total, 698 patients fulfilled the eligibility criteria. Among them, 265 of 482 patients (55.0%) in the training cohort and 120 of 216 (55.6%) patients in the validation cohort developed ER. The preoperative risk factors associated with ER were age, alpha-fetoprotein, tumor diameter, and tumor number, and the postoperative risk factors associated with ER were age, tumor diameter, tumor number, microvascular invasion, and differentiation. The pre- and postoperative nomograms based on these factors showed good accuracy, with concordance indices of 0.712 and 0.850 in the training cohort, respectively, and 0.754 and 0.857 in the validation cohort, respectively. The calibration curves showed optimal agreement between the predictions by the nomograms and actual observations. The area under the receiver operating characteristic curves of the pre- and postoperative nomograms were 0.721 and 0.848 in the training cohort, respectively, and 0.754 and 0.844 in the validation cohort, respectively.

CONCLUSIONS

The nomograms constructed in this study showed good performance in predicting ER for HCC without macrovascular invasion before and after surgery. These nomograms would be helpful for doctors when determining treatments and selecting patients for regular surveillance or administration of adjuvant therapies.

Mapping of Level I Axillary Lymph Nodes in Patients with Newly Diagnosed Breast Cancer: Optimal Target Delineation and Treatment Techniques for Breast and Level I Axilla irradiation

PURPOSE

To map the locations of level I axilla (Ax-L1) lymph nodes (LNs), evaluate the clinical target volume (CTV) coverage defined by the Radiation Therapy Oncology Group (RTOG) breast cancer atlas, and assess the optimal techniques for whole-breast and Ax-L1 irradiation (WBI + Ax-L1).

MATERIALS AND METHODS

We identified 76 newly diagnosed breast cancer patients with 1-4 positive LNs confirmed by axillary dissection. The locations of 116 involved Ax-L1 LNs on diagnostic computed tomography (CT) were mapped onto simulated CT images of a standard patient. Ax-L1 LN coverage by the RTOG atlas was evaluated, and a modified Ax-L1 CTV with better coverage was proposed. Treatment plans were designed for WBI + Ax-L1 with high tangential simplified intensity-modulated radiation therapy (HT-sIMRT) and volumetric modulated arc therapy (VMAT), and for WBI + RTOG Ax-L1 with VMAT with a prescription dose of 50 Gy in 25 fractions, respectively. The differences in dosimetric parameters were compared.

RESULTS

The RTOG atlas missed 29.3% of LNs. Modification by extending 1 cm caudal and 0.5 cm anterior to the RTOG-defined CTV borders allowed the modified Ax-L1 CTV to encompass 90.5% of LNs. All plans met the required prescription dose to WBI and Ax-L1. The mean dose and V20 and V5 of the ipsilateral lung were 11.7Gy, 23.0%, 38.1% for HT-sIMRT WBI + Ax-L1, and 8.9 Gy, 16.4%, 32.5% for VMAT WBI + Ax-L1 plans, respectively. The mean heart doses in the left-sided plans were 3.2Gy and 3.0Gy, respectively. The V30 of the humeral head and minimum dose to the axillary-lateral thoracic vessel junction were 2.0% vs 1.8%, and 45.5Gy vs 45.7Gy for VMAT WBI + Ax-L1 and VMAT WBI + RTOG Ax-L1 plans, respectively.

CONCLUSIONS

A modified Ax-L1 CTV with expansion of the caudal and anterior borders might provide better coverage. Compared with HT-sIMRT WBI + Ax-L1, VMAT WBI+ Ax-L1 provided an adequate dose to Ax-L1 with decreasing the doses to most normal tissues. Coverage of modified Ax-L1 did not increase the dose to organs-at-risk compared with coverage of RTOG Ax-L1.

Manual Lymph Drainage With Progressive Arm Exercises for Axillary Web Syndrome After Breast Cancer Surgery: A Randomized Controlled Trial

OBJECTIVE

This study aimed to determine the effectiveness of a physical therapist-designed program tailored to axillary web syndrome (AWS) in women after breast cancer surgery.

METHODS

A prospective, single-center, assessor-blinded, randomized controlled trial was conducted at the Physiotherapy in Women's Health Research Unit of the Alcalá University (Madrid, Spain). Ninety-six women with AWS were assigned to the physical therapy group (manual lymph drainage [MLD] using resorption strokes and arm exercises as if performing median nerve neurodynamic glide exercises with no neural loading; n = 48) or the control group (standard arm exercises; n = 48), with both groups receiving treatment 3 times a week for 3 weeks. Both interventions included an educational component.

RESULTS

Compared with the control group, the physical therapy group showed significant and clinically relevant improvements in the primary outcome (self-reported pain intensity) at the primary and 3-month follow-ups. Significant and clinically relevant differences between groups were also found in the secondary outcomes (shoulder active range of motion, shoulder disability, and physical and functional aspects of health-related quality of life) at the primary follow-up and in the secondary outcomes as well as the trial outcome index at the 3-month follow-up. No significant differences were found at the 6-month follow-up in either primary or secondary outcomes.

CONCLUSION

The physical therapy program tailored to AWS was found to be effective for AWS symptoms in women after breast cancer surgery, both immediately after the program and after 3 months.

IMPACT

To our knowledge, this is the first appropriately designed study to demonstrate the effectiveness of MLD with progressive arm exercises for AWS. Clinicians and health service providers should consider how to provide survivors of breast cancer with AWS the opportunity to participate in physical therapy programs, including MLD with progressive arm exercises.

LAY SUMMARY

For axillary web syndrome following breast cancer surgery, a physical therapist can design a treatment program including manual lymph drainage and progressive arm exercises, which has been shown to result in reduced pain and improved motion compared with standard arm exercises.

A historical literature review on the role of posterior axillary boost field in the axillary lymph node coverage and development of lymphedema following regional nodal irradiation in breast cancer

To elucidate whether (1) a posterior axillary boost (PAB) field is an optimal method to target axillary lymph nodes (LNs); and (2) the addition of a PAB increases the incidence of lymphedema, a systematic review was undertaken. A literature search was performed in the PubMed database. A total of 16 studies were evaluated. There were no randomized studies. Seven articles have investigated dosimetric aspects of a PAB. The remaining 9 articles have determined the effect of a PAB field on the risk of lymphedema. Only 2 of 9 articles have prospectively reported the impact of a PAB on the risk of lymphedema development. There are conflicting reports on the necessity of a PAB. The PAB field provides a good coverage of level I/II axillary LNs because these nodes are usually at a greater depth. The main concern regarding a PAB is that it produces a hot spot in the anterior region of the axilla. Planning studies optimized a traditional PAB field. Prospective studies and the vast majority of retrospective studies have reported the use of a PAB field does not result in increasing the risk of lymphedema development over supraclavicular-only field. The controversies in the incidence of lymphedema suggest that field design may be more important than field arrangement. A key factor regarding the use of a PAB is the depth of axillary LNs. The PAB field should not be used unless there is an absolute indication for its application. Clinicians should weigh lymphedema risk in individual patients against the limited benefit of a PAB, in particular after axillary dissection. The testing of the inclusion of upper arm lymphatics in the regional LN irradiation target volume, and universal methodology measuring lymphedema are all areas for possible future studies.

Feasibility of arm-draining lymph node-sparing radiotherapy of breast cancer: A pilot planning study

INTRODUCTION

Lymphoedema following axillary radiotherapy for breast cancer causes significant morbidity. Our goal was to evaluate the feasibility of sparing the lymph node that drains the arm's lymphatics (ARM node) while achieving standard dose constraints for whole breast and comprehensive lymph node irradiation.

METHODS

Six patients underwent lymphoscintigraphy and SPECT CT to identify the breast sentinel node (SN) and ARM node. The ARM node was contoured on the SPECT CT and deformably registered to the radiotherapy treatment planning CT. Radiotherapy plans (50 Gy in 25 fractions) with VMAT technique were generated, with the aim to spare the ARM node (Mean dose <25 Gy) and achieve adequate coverage to the remaining axilla. The plan required the breast SN site (clip + 10 mm surrounding the clip) to achieve D98% > 47.5 Gy, and axillary nodal CTV excluding ARM node to achieve D90% > 45 Gy.

RESULTS

In one patient, the ARM node was within the volume of breast SN site and sparing was not possible. For the remaining 5 patients, an ARM node-sparing plan could be successfully generated; the mean dose to the ARM node ranged from 11.2 to 23.1 Gy (median 13.8 Gy). In these 5 subjects, D90% > 45 Gy of axillary nodal CTV (range, 44.9-48.5 Gy, median 46.2 Gy) and D98% > 47.5 Gy of breast SN site were achieved.

CONCLUSION

In this planning study, ARM node-sparing VMAT of the breast and lymph nodes was feasible, while maintaining adequate dosimetric coverage. However, in some individuals, localization of the ARM node in close proximity to breast SN site precluded the generation of an ARM node-sparing treatment plan.

A National Survey of Breast Surgeons and Radiation Oncologists on Contemporary Axillary Management in Mastectomy Patients

BACKGROUND

Management of axillary lymph nodes in breast cancer has undergone significant change over the past decade through landmark clinical trials. This study aimed to assess national practice patterns in axillary management in patients undergoing upfront mastectomy and examines what guides provider recommendations.

METHODS

A national case-based survey study was performed of surgeons and radiation oncologists from July to August 2020. Surgeons were identified through the American Society of Breast Surgeons (ASBrS) after review and approval by the ASBrS Research Committee, and radiation oncologists were identified through an institutional database. Both descriptive and comparative statistical analyses were performed.

RESULTS

Overall, 994 providers responded-680 surgeons and 314 radiation oncologists. Surgeons were older and in practice longer (p < 0.05) and treated a higher percentage of breast patients (81% vs. 40%, p < 0.001). Most surgeons were hospital-employed (43%), whereas most radiation oncologists were in private practice (40%; p < 0.001). Fifty-two percent of surgeons routinely send sentinel lymph nodes (SLNs) for frozen section (52%) during mastectomy, of which 78% proceed directly to axillary lymph node dissection (ALND) if positive. There was significant variability in treatment recommendations between the two groups among the hypothetical cases (p < 0.001). In the setting of low disease burden in the SLNs, > 30% of surgeons recommended ALND, while radiation oncologists recommend axillary radiotherapy over axillary clearance (p < 0.001).

CONCLUSION

There is significant heterogeneity in the management of the axilla in mastectomy patients with pathologically positive SLNs, both between and among surgeons and radiation oncologists. Efforts should be made to assist both groups in identifying de-escalation opportunities to ensure that mastectomy patients with positive SLNs are treated appropriately.

Auxiliary Structures-Assisted Radiotherapy Improvement for Advanced Left Breast Cancer

Background

To improve the quality of plan for the radiation treatment of advanced left breast cancer by introducing the auxiliary structures (ASs) which are used to spare the regions with no intact delineated structures adjacent to the target volume.

Methods

CT data from 20 patients with left-sided advanced breast cancer were selected. An AS designated as A1 was created to spare the regions of the aorta, pulmonary artery, superior vena ava, and contralateral tissue of the upper chest and neck, and another, designated as A2, was created in the regions of the cardia and fundus of the stomach, left liver lobe, and splenic flexure of the colon. IMRT and VMAT plans were created for cases with and without the use of the AS dose constraints in plan optimization. Dosimetric parameters of the target and organs at risk (OARs) were compared between the separated groups.

Results

With the use of AS dose constraints, both the IMRT and VMAT plans were clinically acceptable and deliverable, even showing a slight improvement in dose distribution of both the target and OARs compared with the AS-unused plans. The ASs significantly realized the dose sparing for the regions and brought a better conformity index (p < 0.05) and homogeneity index (p < 0.05) in VMAT plans. In addition, the volume receiving at least 20 Gy (V₂₀) for the heart (p < 0.05), V₄₀ for the left lung (p < 0.05), and V₄₀ for the axillary-lateral thoracic vessel juncture region (p < 0.05) were all lower in VMAT plans.

Conclusion

The use of the defined AS dose constraints in plan optimization was effective in sparing the indicated regions, improving the target dose distribution, and sparing OARs for advanced left breast cancer radiotherapy, especially those that utilize VMAT plans.

Development and Validation of an Intraoperative Nomogram to Predict Breast Cancer-Related Lymphedema Based on the Arm Lymphatics Distribution

BACKGROUND

Preoperatively determining those patients who are at high risk of encountering breast cancer-related lymphedema (BCRL) is still not well understood.

OBJECTIVE

This study aimed to develop a simple intraoperative nomogram for BCRL, incorporating a protective factor.

METHODS

Overall, 320 breast cancer patients at Zhongnan Hospital (training set) and 221 patients at Dongfeng General Hospital (external validation cohort) treated between November 2017 and December 2018 were included. Prior to axillary lymph node dissection (ALND), 1 mL (2.5 mg) of indocyanine green was administered to the area of the internal bicipital sulcus of the upper limb. The fluorescence image was obtained and the proportion of arm lymph flow above the level of the axillary vein was calculated. Multivariate logistic regression was performed using this proportion together with clinical data. A nomogram was then constructed and assessed for its discrimination and calibration ability and clinical utility in the training and external validation sets.

RESULTS

The cumulative incidence of BCRL was 18.7% (60/320), with a median follow-up of 29 months (20-34). In the multivariate logistic regression analysis, body mass index, taxane, radiotherapy, and proportion of arm lymph flow above the level of the axillary vein were identified as independent risk factors. In the training and validation cohorts, the calibration curve performed well (p = 0.721 and p = 0.315, respectively), and the area under the receiver operating characteristic curve values were 0.829 (95% confidence interval [CI] 0.773-0.885) and 0.804 (95% CI 0.732-0.877), respectively.

CONCLUSION

High-risk patients could be identified intraoperatively with this nomogram, and timely intervention could be performed with preservation of the arm lymphatics.

The Risk of Subclinical Breast Cancer-Related Lymphedema by the Extent of Axillary Surgery and Regional Node Irradiation: A Randomized Controlled Trial

PURPOSE

To compare the risk of subclinical breast cancer-related lymphedema (sBCRL) using bioimpedance spectroscopy (BIS) or tape measure (TM) by the extent of axillary surgery and regional nodal irradiation (RNI).

METHODS AND MATERIALS

Patients were randomized to surveillance with TM or BIS. A BIS ≥6.5 L-Dex units or TM volume change ≥5 and <10% above presurgical baselines "triggered" sBCRL. The incidence of sBCRL by sentinel node biopsy or axillary lymph node dissection (ALND) with or without RNI was examined for 484 patients. Radiation was categorized as "limited RNI" (axilla level I/II only) or "extensive RNI" (axilla level III or supraclavicular fossa with or without level I/II).

RESULTS

At a median follow-up of 20.5 months, 109 of 498 patients (21.9%) triggered sBCRL (BIS 13.5% vs TM 25.6%; P <.001). In patients not receiving RNI, BIS triggered 12.9% of patients undergoing SNB and 25.0% undergoing ALND (P = .18). Extensive RNI significantly increased triggering with BIS versus no RNI after sentinel node biopsy (SNB; 33.3% vs 12.9%; P = .03) but not ALND (30.8% vs 25.0%; P = .69). Triggering by TM was greater than 25% for most subgroups and was inferior to BIS in discriminating the risk of sBCRL by utilization of RNI or axillary surgery.

CONCLUSIONS

The lower triggering rates with BIS and its better discrimination of the risk of sBCRL by receipt and type of RNI compared with TM support its use for posttreatment surveillance to detect sBCRL and to initiate early intervention. The risk of sBCRL increased with more extensive axillary treatment. Patients having ALND or extensive RNI require close surveillance for BCRL. Longer follow-up is required to determine rates of progression to clinical lymphedema.

Longitudinal impact of postmastectomy radiotherapy on arm lymphedema in patients with breast cancer: An analysis of serial changes in arm volume measured by infrared optoelectronic volumetry

BACKGROUND AND PURPOSE

This study was conducted to evaluate the longitudinal impact of postmastectomy radiation therapy (PMRT) on persistent severe lymphedema (PSL) using arm volume measurements by an infrared optoelectronic volumetry.

MATERIALS AND METHODS

Of the patients who underwent mastectomy between 2008 and 2016, we included 330 patients with secondary arm lymphedema. Percentage of excessive volume (PEV) of the arm were serially assessed using an optoelectronic volumetry 1, 3, 6, 12, 18, 24, 36, and 48 months after the lymphedema diagnosis (T_{lymh_Dx}). We defined PSL as 2 or more episodes of PEV ≥ 20%. Risk factors for PSL were evaluated using stepwise regression analyses.

RESULTS

Patients who received PMRT (n = 202, 61.2%) were more likely to have larger extent of axillary node dissection (AND), and frequent stage II/III lymphedema at T_{lymh_Dx} than those who did not receive PMRT (p < 0.001). With a median follow-up of 72.5 months, PSL occurred in 71 (21.5%) patients. Patients with PSL were more frequently treated with AND of ≥ 20 nodes without reconstruction, had advanced lymphedema stage and higher PEV at T_{lymh_Dx}, and more frequent events of cellulitis compared to those without PSL. The risk of developing PSL was significantly associated with PMRT with regional node irradiation (RNI), AND of ≥20 nodes, lymphedema stage, and PEV at T_{lymh_Dx}, cellulitis, and compliance with physical therapy.

CONCLUSION

PMRT, especially RNI, was associated with a consistent increase in PEV in patients with arm lymphedema. Therefore, timely physical therapy is necessary for this patient population.

Clinical feasibility of deep learning-based auto-segmentation of target volumes and organs-at-risk in breast cancer patients after breast-conserving surgery

Background

In breast cancer patients receiving radiotherapy (RT), accurate target delineation and reduction of radiation doses to the nearby normal organs is important. However, manual clinical target volume (CTV) and organs-at-risk (OARs) segmentation for treatment planning increases physicians’ workload and inter-physician variability considerably. In this study, we evaluated the potential benefits of deep learning-based auto-segmented contours by comparing them to manually delineated contours for breast cancer patients.

Methods

CTVs for bilateral breasts, regional lymph nodes, and OARs (including the heart, lungs, esophagus, spinal cord, and thyroid) were manually delineated on planning computed tomography scans of 111 breast cancer patients who received breast-conserving surgery. Subsequently, a two-stage convolutional neural network algorithm was used. Quantitative metrics, including the Dice similarity coefficient (DSC) and 95% Hausdorff distance, and qualitative scoring by two panels from 10 institutions were used for analysis. Inter-observer variability and delineation time were assessed; furthermore, dose-volume histograms and dosimetric parameters were also analyzed using another set of patient data.

Results

The correlation between the auto-segmented and manual contours was acceptable for OARs, with a mean DSC higher than 0.80 for all OARs. In addition, the CTVs showed favorable results, with mean DSCs higher than 0.70 for all breast and regional lymph node CTVs. Furthermore, qualitative subjective scoring showed that the results were acceptable for all CTVs and OARs, with a median score of at least 8 (possible range: 0–10) for (1) the differences between manual and auto-segmented contours and (2) the extent to which auto-segmentation would assist physicians in clinical practice. The differences in dosimetric parameters between the auto-segmented and manual contours were minimal.

Conclusions

The feasibility of deep learning-based auto-segmentation in breast RT planning was demonstrated. Although deep learning-based auto-segmentation cannot be a substitute for radiation oncologists, it is a useful tool with excellent potential in assisting radiation oncologists in the future.

Trial registration Retrospectively registered.

Anatomy and physiology of the sentinel lymph nodes of the upper extremity: Implications for axillary reverse mapping in breast cancer

BACKGROUND

This study characterizes the physiological drainage of the normal upper extremity using single-photon emission computed tomography/computed tomography (SPECT/CT) lymphoscintigraphy axillary reverse lymphatic mapping (ARM).

METHODS

A consecutive series of patients assessed with SPECT/CT lymphoscintigraphy ARM of the upper extremity were included. Anatomical localization of the axillary sentinel lymph nodes (SLN) was completed in normal axillae in relation to consistent anatomic landmarks. Retrospective case note analysis was performed to collect patient demographic data.

RESULTS

A total of 169 patients underwent SPECT/CT lymphoscintigraphy, and imaging of 182 normal axillae was obtained. All patients (100%) had an axillary SLN identified: 19% had a single contrast-enhanced SLN in the axilla and the remainder had multiple. The SLN(s) of the upper extremity was located in the upper outer quadrant (UOQ) of the axilla in 97% of cases (177 axillae). When the SLN(s) was found in the UOQ of the axilla, second-tier lymph nodes were found predominantly in the upper inner quadrant (50% of cases).

CONCLUSIONS

The upper extremity SLN(s) is located in a constant region of the axilla. This study provides the most complete investigation to date and results can be directly applied clinically to ARM techniques and adjuvant radiation planning.

Quantifying the Impact of Axillary Surgery and Nodal Irradiation on Breast Cancer-Related Lymphedema and Local Tumor Control: Long-Term Results From a Prospective Screening Trial

PURPOSE

To independently evaluate the impact of axillary surgery type and regional lymph node radiation (RLNR) on breast cancer-related lymphedema (BCRL) rates in patients with breast cancer.

PATIENTS AND METHODS

From 2005 to 2018, 1,815 patients with invasive breast cancer were enrolled in a lymphedema screening trial. Patients were divided into the following 4 groups according to axillary surgery approach: sentinel lymph node biopsy (SLNB) alone, SLNB+RLNR, axillary lymph node dissection (ALND) alone, and ALND+RLNR. A perometer was used to objectively assess limb volume. All patients received baseline preoperative and follow-up measurements after treatment. Lymphedema was defined as a ≥ 10% relative increase in arm volume arising > 3 months postoperatively. The primary end point was the BCRL rate across the groups. Secondary end points were 5-year locoregional control and disease-free-survival.

RESULTS

The cohort included 1,340 patients with SLNB alone, 121 with SLNB+RLNR, 91 with ALND alone, and 263 with ALND+RLNR. The overall median follow-up time after diagnosis was 52.7 months for the entire cohort. The 5-year cumulative incidence rates of BCRL were 30.1%, 24.9%, 10.7%, and 8.0% for ALND+RLNR, ALND alone, SLNB+RLNR, and SLNB alone, respectively. Multivariable Cox models adjusted for age, body mass index, surgery, and reconstruction type showed that the ALND-alone group had a significantly higher BCRL risk (hazard ratio [HR], 2.66; P = .02) compared with the SLNB+RLNR group. There was no significant difference in BCRL risk between the ALND+RLNR and ALND-alone groups (HR, 1.20; P = .49) and between the SLNB-alone and SLNB+RLNR groups (HR, 1.33; P = .44). The 5-year locoregional control rates were similar for the ALND+RLNR, ALND-alone, SLNB+RLNR, and SLNB-alone groups (2.8%, 3.8%, 0%, and 2.3%, respectively).

CONCLUSION

Although RLNR adds to the risk of lymphedema, the main risk factor is the type of axillary surgery used.

Axillary nodal irradiation practice in the sentinel lymph node biopsy era: Comparison of the contemporary available 3D and IMRT techniques

OBJECTIVE

Our study aimed to compare regional node coverage and doses to the organ at risk (OAR) using conventional technique (CT) vs "AMAROS" (AT) vs intensity-modulated radiation therapy (IMRT) techniques in patients receiving regional nodal irradiation (RNI) for breast cancer (BC).

METHODS

We included 30 consecutive patients with BC who received RNI including axillary nodes. Two independent and blinded dosimetric RNI plans were generated for all patients. For target volume coverage, we analyzed the V95%, the D95%, the mean and the minimal dose within the nodal station. For hotspots within nodal target volume, we used the V105%, the V108% and the maximal doses. For OAR, lung V20, mean lung and heart doses, the maximal dose to the brachial plexus and the axillary-lateral thoracic vessel junction region were compared between the three techniques.

RESULTS

Target volume coverage and hotspots: Mean V95% in stations I, II, III and IV were 35.8% and 75% respectively with CV, 22.59 and 59.9% respectively with AT technique and 45.58 and 99.6% respectively with IMRT with statistically significant differences (p < 0.001). Mean V105% (cc) in axillary and supraclavicular stations were 21.3 and 6.4 respectively with CV, 1.2 and 0.02 respectively with AT technique and 0.5 and 0.4 respectively with IMRT with statistically significant differences (p < 0.001)..OARs: The mean ipsilateral lung V20 was 16.9%, 16.4 and 13.3% with CT, AT and IMRT respectively. The mean heart dose (Gy) was 0.3, 0.2 and 0.2 with CT, AT and IMRT respectively. The maximal dose to the plexus brachial (Gy) was 50.3, 46.3 and 47.3 with CT, AT and IMRT respectively. The maximal dose to the axillary-lateral thoracic vessel junction (Gy) was 52.3, 47.3 and 47.6 with CT, AT and IMRT respectively. The differences were statistically significant for all OAR (p < 0.001).

CONCLUSION

AT is a valuable technique for RNI including axilla in patients with limited sentinel lymph node biopsy involvement without additional axillary lymph node dissection since it decreases hotspots in the target volume and lowers the radiation exposure of the OAR. For more advanced tumors or patients who did not respond to primary systemic therapy, CT or IMRT should be considered because of their better coverage of the potentially residual nodal disease. IMRT combines several advantages of offering high conformal plans, limited hotspots and protection of main OAR. The clinical impact of these dosimetric differences need to be addressed.

ADVANCES IN KNOWLEDGE

This study is to our knowledge the first to compare conventional three-dimensional and IMRT techniques for regional nodal irradiation for each nodal station in breast cancer in a context of increasing utilization of axillary irradiation.

Comparison of Nodal Target Volume Definition in Breast Cancer Radiation Therapy According to RTOG Versus ESTRO Atlases: A Practical Review From the TransAtlantic Radiation Oncology Network (TRONE)

Regional nodal irradiation has gained interest in recent years with the publication of several important randomized trials and the availability of more conformal techniques. Target volume delineation represents a critical step in the radiation planning process. Adequate coverage of the microscopic tumor spread to regional lymph nodes must be weighed against exposure of critical structures such as the heart and lungs. Among available guidelines for delineating the clinical target volume for the breast/chest wall and regional nodes, the Radiation Therapy Oncology Group and European Society for Radiotherapy and Oncology guidelines are the most widely used internationally. These guidelines have been formulated based on anatomic boundaries of areas historically covered in 2-dimensional field-based radiation therapy but have not been validated by patterns-of-failure studies. In recent years, an important body of data has emerged from mapping studies documenting patterns of local and regional recurrence. We aim to review, discuss, and compare contouring guidelines for breast cancer radiation therapy in the context of contemporary data on locoregional relapse to improve their implementation in modern practice.

Mapping of Metastatic Level I Axillary Lymph Nodes in Patients with Newly Diagnosed Breast Cancer

PURPOSE

We examined the distribution of pretreatment nodal metastases to the level I axilla (Ax-L1) to assess the appropriateness of current breast atlases and provide guidelines in relationship to easily identifiable anatomic landmarks for accurate delineation of this lymph node (LN) basin.

METHODS AND MATERIALS

Patients with newly diagnosed breast cancer and biopsy-proven metastatic Ax-L1 LNs were identified. We related the location of each LN to its most adjacent rib and its distance from the bottom of the humeral head, axillary vessels, and a line connecting the anterior aspects of the pectoralis and latissimus dorsi muscles (P-L line). LNs were mapped onto a representative planning computed tomography scan, and their distribution was used to validate the current Radiation Therapy Oncology Group, European Society for Radiotherapy and Oncology, and Radiotherapy Comparative Effectiveness breast atlases. Furthermore, we examined metastases to a subregion encompassing the superolateral Ax-L1, irradiation of which correlates highly with lymphedema.

RESULTS

We identified 106 eligible patients with 107 biopsied LNs. All LNs fell between the second and fifth ribs (mean, 3.8 ± 0.56). Mean distance from the inferior aspect of the humeral head was 4.3 ± 1.6 cm (range, 0.3-8.4). Mean distance from the inferior aspect of the axillary vessels was 2.9 ± 1.5 cm (range, -0.6 to 5.4). Mean distance from the P-L line was 0.01 ± 1.9 cm (range, -2.2 to 2.4); negative and positive values denote medial or lateral to the P-L line. A Radiation Therapy Oncology Group-compliant Ax-L1 consensus contour, created from contours by 4 attending breast radiation oncologists, partially or fully missed 45% of mapped LNs. European Society for Radiotherapy and Oncology- and Radiotherapy Comparative Effectiveness-compliant Ax-L1 similarly missed 46% and 34% of mapped LNs, respectively. LNs were most frequently missed in the lateral direction. The superolateral Ax-L1 encompassed 9.3% of the mapped LNs.

CONCLUSIONS

A significant percentage of at-risk Ax-L1 tissue falls outside current contouring atlases. We propose expansion of the recommended Ax-L1 borders, most notably in the lateral direction.