Loco-regional conformal radiotherapy of the breast: delineation of the regional lymph node clinical target volumes in treatment position

Optimization of supraclavicular lymph node clinical target volume delineation in high-risk breast cancer: a single center experience and recommendation

BACKGROUND

Prophylactic irradiation of supraclavicular lymph node drainage areas can improve the regional control rate of lymph node-positive or lymph node-negative disease but a locally-advanced stage breast cancer, and it can reduce breast cancer-related mortality. However, many controversies exist in the clinical target volume delineation of supraclavicular lymph node drainage in patients with breast cancer.

METHODS

We retrospectively analyzed 42 patients with breast cancer and supraclavicular lymph node metastasis at our hospital between January 2017 and December 2021. Among these cases, 32 were locally advanced and 10 were stage IV at initial treatment. A patient with breast cancer who did not undergo dissection of the supraclavicular and infraclavicular lymph nodes at our hospital was selected as a standard patient. A contrast-enhanced computed tomography (CT) scan for positioning was used as a template image, and blood vessels, muscles, and bony landmarks were used as references for positioning. The metastatic supraclavicular lymph nodes were identified in all enrolled patients and projected into the template CT images.

RESULTS

The metastastic pattern of supraclavicular lymph node in breast cancer was proposed: distribution along the posterolateral border of the internal jugular vein (medial supraclavicular group) and along the transverse jugular vein (lateral supraclavicular group). We theorized that the lateral and posterior borders of the clinical target volume in the supraclavicular region should include the lymph nodes in the posterior triangle of the neck (level V) in high-risk individuals. If the metastatic axillary lymph node is extensive, then the superior border of the supraclavicular region should be moved upward appropriately.

CONCLUSIONS

This study analyzed patients with breast cancer and supraclavicular lymph node metastasis at initial treatment, explored the metastastic pattern of supraclavicular lymph node, and applied anatomical knowledge to further optimize the target volume delineation of supraclavicular lymph node drainage area in high-risk breast cancer.

Individualized Clinical Target Volume for Irradiation of the Supraclavicular Region in Breast Cancer Based on Mapping of the Involved Ipsilateral Supraclavicular Lymph Nodes

PURPOSE

To map supraclavicular fossa-involved lymph nodes (SCF-LNs) in patients with nonmetastatic breast cancer, evaluate the coverage of widely adopted atlases, and propose modified borders for individualized regional irradiation.

METHODS AND MATERIALS

M0 patients with biopsy-proven SCF-LNs who were SCF treatment-naïve were included. The SCF was spatially divided into subregions, with each node mapped on the original images. The geographic misses after the borders of multiple atlases were evaluated and factors affecting SCF-LNs' spread pattern were analyzed.

RESULTS

From 1998 to 2022, 209 patients with 1242 SCF-LNs were eligible. Patients had a median of 4 nodes. At least 537 nodes (43.2%) in 147 patients (70.3%) were lateral to the sternocleidomastoid muscle (SCM), and 403 nodes (32.4%) in 127 patients (60.8%) were dorsal to the anterior scalene muscle (ASM). In the 88 patients with ≤3 SCF-LNs, at least 66 nodes (39.1%) in 40 patients (45.5%) were lateral to the SCM, and 34 nodes (20.1%) in 29 patients (33.0%) were dorsal to the ASM. These nodes were not covered by the Radiation Therapy Oncology Group (RTOG) atlas and partly within the Radiotherapy Comparative Effectiveness atlas. One hundred four patients (49.8%) had 432 SCF-LNs (34.8%) beyond the upper border of the European Society for Radiotherapy and Oncology (ESTRO) atlas. In multivariate regression, nodal sizes were associated with wider spread in the primary group. Being triple-negative (TN) subtype was associated with less spread in the recurrent group. Situation-based clinical target volumes (CTVs) were theorized, in which for a sequential spread, the posterior border could be the posterior scalene muscle or even be more constringent; otherwise, it should touch the anterior trapezius surface.

CONCLUSIONS

SCF-LNs tend to spread laterally and dorsally beyond the RTOG borders, even in M0 stages with ≤3 SCF-LNs. The ESTRO upper border does not guarantee coverage with multiple SCF-LNs. Nodal burden and non-TN types are predictive of wider dissemination. A situation-based CTV is possibly feasible. Deciphering the SCF-LN spread route is needed.

Delineation guidelines for the lymphatic target volumes in 'prone crawl' radiotherapy treatment position for breast cancer patients

Our recently developed prone crawl position (PCP) for radiotherapy of breast cancer patients with lymphatic involvement showed promising preliminary data and it is being optimized for clinical use. An important aspect in this process is making new, position specific delineation guidelines to ensure delineation (for treatment planning) is uniform across different centers. The existing ESTRO and PROCAB guidelines for supine position (SP) were adapted for PCP. Nine volunteers were MRI scanned in both SP and PCP. Lymph node regions were delineated in SP using the existing ESTRO and PROCAB guidelines and were then translated to PCP, based on the observed changes in reference structure position. Nine PCP patient CT scans were used to verify if the new reference structures were consistently identified and easily applicable on different patient CT scans. Based on these data, a team of specialists in anatomy, CT- and MRI radiology and radiation oncology postulated the final guidelines. By taking the ESTRO and PROCAB guidelines for SP into account and by using a relatively big number of datasets, these new PCP specific guidelines incorporate anatomical variability between patients. The guidelines are easily and consistently applicable, even for people with limited previous experience with delineations in PCP.

A dosimetric study to improve the quality of nodal radiotherapy in breast cancer

Objectives:

Field-based planning for regional nodal breast radiotherapy (RT) used to be standard practice. This study evaluated a field-based posterior axillary boost (PAB) and two forward-planned intensity-modulated RT (IMRT) techniques, aiming to replace the first.

Methods:

Supraclavicular and axillary nodes, humeral head, brachial plexus, thyroid, and oesophagus were retrospectively delineated on 12 CT scans. Three plans, prescribed to 40.05 Gy, were produced for each patient. Breast plans consisted of field-in-field IMRT tangential fields in all three techniques. Nodal plans consisted of a field-based PAB (anterior and posterior boost beam), and 2 forward-planned techniques: simple IMRT 1 (anterior and posterior beam with limited segments), and a more advanced IMRT 2 technique (anterior and fully modulated posterior beam).

Results:

The nodal V_90% was similar between IMRT 1: mean 99.5% (SD 1.0) and IMRT 2: 99.4% (SD 0.5). Both demonstrated significantly improved results (p = 0.0001 and 0.005, respectively) compared to the field-based PAB technique. IMRT 2 lung V_12Gy and humeral head V_10Gy were significantly lower (p = 0.002, 0.0001, respectively) than the field-based PAB technique. IMRT 1 exhibited significantly lower brachial plexus D_max and humeral head V₅, ₁₀, and _15Gy doses (p = 0.007, 0.013, 0.007 and 0.007, respectively) compared to the field-based PAB technique. The oesophagus and thyroid dose difference between methods was insignificant.

Conclusions:

Both IMRT techniques achieved the dose coverage requirements and reduced normal tissue exposure, decreasing the risk of radiation side effects. Despite the increased cost of IMRT, compared to non-IMRT techniques ¹, both IMRT techniques are suitable for supraclavicular and axillary nodal RT.

Advances in knowledge:

Forward-planned IMRT already resulted in significant dose reduction to organs at risk and improved planning target volume coverage.¹ This new, simplified forward-planned IMRT one technique has not been published in this context and is easy to implement in routine clinical practice.

Geometric contour variation in clinical target volume of axillary lymph nodes in breast cancer radiotherapy: an AIRO multi-institutional study

OBJECTIVES

To determine interobserver variability in axillary nodal contouring in breast cancer (BC) radiotherapy (RT) by comparing the clinical target volume of participating single centres (SC-CTV) with a gold-standard CTV (GS-CTV).

METHODS

The GS-CTV of three patients (P1, P2, P3) with increasing complexity was created in DICOM format from the median contour of axillary CTVs drawn by BC experts, validated using the simultaneous truth and performance-level estimation and peer-reviewed. GS-CTVs were compared with the correspondent SC-CTVs drawn by radiation oncologists, using validated metrics and a total score (TS) integrating all of them.

RESULTS

Eighteen RT centres participated in the study. Comparative analyses revealed that, on average, the SC-CTVs were smaller than GS-CTV for P1 and P2 (by -29.25% and -27.83%, respectively) and larger for P3 (by +12.53%). The mean Jaccard index was greater for P1 and P2 compared to P3, but the overlap extent value was around 0.50 or less. Regarding nodal levels, L4 showed the highest concordance with the GS. In the intra-patient comparison, L2 and L3 achieved lower TS than L4. Nodal levels showed discrepancy with GS, which was not statistically significant for P1, and negligible for P2, while P3 had the worst agreement. DICE similarity coefficient did not exceed the minimum threshold for agreement of 0.70 in all the measurements.

CONCLUSIONS

Substantial differences were observed between SC- and GS-CTV, especially for P3 with altered arm setup. L2 and L3 were the most critical levels. The study highlighted these key points to address.

ADVANCES IN KNOWLEDGE

The present study compares, by means of validated geometric indexes, manual segmentations of axillary lymph nodes in breast cancer from different observers and different institutions made on radiotherapy planning CT images. Assessing such variability is of paramount importance, as geometric uncertainties might lead to incorrect dosimetry and compromise oncological outcome.

Atlas of sentinel lymph nodes in early breast cancer using single-photon emission computed tomography: implication for lymphatic contouring

PURPOSE

to determine the localization of sentinel lymph nodes (SLNs) in a large cohort of patients with breast cancer and validate the European Society for Therapeutic Radiology and Oncology (ESTRO), Radiation Therapy Oncology Group (RTOG), and Radiotherapy Comparative Effectiveness (RADCOMP) guidelines on regional lymph node clinical target volume (CTV-LN) delineation.

MATERIALS AND METHODS

A total of 254 women with cT1-3N0-1M0 breast cancer underwent single-photon emission computed tomography (SPECT-CT) visualization of SLNs after intra- and peritumoral injection of 99mTc-radiocolloids. All SPECT-CT images were fused with reference simulation computed tomography. A 3D atlas of SLNs was created and used for evaluation of CTV-LN defined by contouring guidelines.

RESULTS

SPECT-CT visualized 532 SLNs that were localized in axillary level I in 67.5%, level II in 15.4%, level III in 7.3%, internal mammary in 8.5%, and supraclavicular in 1.3% cases. The majority of level II-IV and internal mammary SLNs were inside the recommended CTV-LN. Axillary level I SLNs were covered by ESTRO and RTOG contours in 85% and 85% cases, respectively. "Out of contours" SLNs were mostly detected in lateral subgroup of level I LN (18.5%), while 98%-99% of anterior pectoral and central axillary SLNs were covered by CTV-LN. Internal mammary SLNs were visualized in 33 cases and were outside ESTRO and RTOG contours in 3 and 6 observations, respectively.

CONCLUSION

SPECT-CT atlas of SLNs demonstrated that in most cases ESTRO and RTOG guidelines correctly represented CTV-LNs with the exception of lateral subgroup of SLNs.

Patterns of supraclavicular area failure after mastectomy in breast cancer patients: implications for target volume delineation

PURPOSE

To characterize the pattern of post-mastectomy supraclavicular lymph node (LN) metastases in patients with breast cancer (BC) and to provide insights for individualized clinical target volume delineation for radiotherapy.

METHODS

We retrospectively analyzed 88 patients with BC who developed post-mastectomy regional LN metastases. The affected regional LNs were categorized as the ipsilateral medial supraclavicular LN area (IMSC-LN), ipsilateral lateral supraclavicular LN area (ILSC-LN), ipsilateral infraclavicular LN area (IIC-LN), and ≥2 groups in the ipsilateral clavicular LN area (MMIC-LN). Clinical characteristics were included in a multivariate analysis to identify risk factors for clavicular LN metastases.

RESULTS

The ILSC-LNs (68.2%) were the most common metastatic site. IMSC-LN metastases showed a significant association with estrogen-receptor (ER) negative status, left-sided BC, and positive axillary LNs. Tumor size ≥2.4 cm and Her2 type were predictors of ILSC-LN metastases. Additionally, tumor size ≥2.4 cm, and level I ipsilateral axillary metastases were associated with MMIC-LN metastasis.

CONCLUSION

ILSC-LN was the most frequently affected group of supraclavicular lymph nodes. ER-negative status, left-sided BC, tumor size, and positive ipsilateral axillary LNs are potentially associated with the pattern of supraclavicular LN metastatic involvement.

Clinical Effectiveness of an Adaptive Treatment Planning Algorithm for Intensity Modulated Radiation Therapy Versus 3D Conformal Radiation Therapy for Node-Positive Breast Cancer Patients Undergoing Regional Nodal Irradiation/Postmastectomy Radiation Therapy

PURPOSE

Clinical trials support adjuvant regional nodal irradiation (RNI) after breast-conserving surgery or mastectomy for patients with lymph node-positive breast cancer. Advanced treatment planning techniques (eg, intensity modulated radiation therapy [IMRT]) can reduce dose to organs at risk (OARs) in this situation. However, uncertainty persists about when IMRT is clinically indicated (vs 3-dimensional conformal radiation therapy [3DCRT]) for RNI. We hypothesized that an adaptive treatment planning algorithm (TPA) for IMRT adoption would allow OAR constraints for RNI to be met when 3DCRT could not without significantly changing toxicity and locoregional recurrence (LRR) patterns.

METHODS AND MATERIALS

Since 2013, all RNI patients also underwent an adaptive TPA that began with 3DCRT and then changed to IMRT when OAR constraints (mean heart dose ≤500 cGy; ipsilateral lung V20 ≤35%) could not be met. Patients received 2 Gy/d to the prospectively contoured target volumes (including internal mammary nodes). We retrospectively evaluated the dosimetry and clinical outcomes of the treatment groups (IMRT vs 3DCRT). The primary endpoint was the cumulative incidence of LRR as the site of first recurrence, and we specifically address patterns of failure based on dose to the posterior supraclavicular nodal region (SCL-post).

RESULTS

Two hundred forty patients (60% stage III; mean 4.0 + nodes) underwent an adaptive-TPA for RNI after mastectomy (74%) or breast-conserving surgery (26%), resulting in 168 patients treated with 3DCRT and 72 patients treated with IMRT. There were 7 LRRs (2 IMRT, 5 3DCRT) resulting in 4-year LRR of 2.8% for IMRT versus 1.8% for 3DCRT (P = .99). Three patients (2 IMRT, 1 3DCRT) had SCL nodal failures (1 in the SCL-post).

CONCLUSIONS

An adaptive TPA for use of IMRT when 3DCRT does not meet critical OAR constraints resulted in rare high-grade toxicity and no difference in failure patterns between patients treated with IMRT and 3DCRT. These data should provide reassurance that IMRT maintains the therapeutic ratio by preserving cancer control outcomes without excess toxicity when 3DCRT fails to meet OAR constraints.

Using the venous angle as a pressure reservoir to retrogradely fill the subclavian lymphatic trunk with contrast agent for lymphatic mapping

BACKGROUND

Visualizing the lymphatic system and recording the spatial relations between the subclavian lymphatic trunk (SLT) and the surrounding anatomical structures will improve radiotherapy treatment planning for breast cancer patients with lymphatic involvement. An experimental approach to retrogradely fill the SLT with contrast agent was explored.

METHODS

Six Thiel embalmed specimens were bilaterally dissected in the cervical and clavicular region to optimize the new experimental approach. A conservative dissection with minimum distortion of spatial relations between different anatomical structures was developed. A pressure reservoir was created inside the venous angle to allow retrograde filling of the SLT under the influence of time and pressure.

RESULTS

The new methodology proved feasible, showing successful pressure build-up inside the venous reservoir, resulting in filling of the proximal end of the subclavian lymphatic trunk. The pressures needed to significantly fill the subclavian lymphatic trunk proved to be higher than the pressures that the venous walls could withstand.

CONCLUSIONS

Thiel embalmed specimens proved useful for optimizing the experimental approach, but the embalming products could have negatively affected the vessel strength. The authors suggest that their method will be applied on fresh frozen specimens in future studies, to obtain SLT filling up to the axillary lymphatic plexus. Our findings also pointed out that there is still a lot to be learned about the anatomical variability of the SLT and its termination sites. The detailed description of our experimental approach offers valuable information for future lymphatic mapping studies.

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.

Definition of Internal Mammary Node Target Volume Based on the Position of the Internal Mammary Sentinel Lymph Nodes Presented on SPECT/CT Fusion Images

Purpose: Mapping the distribution of internal mammary sentinel lymph nodes (IM-SLNs) presented on single photon emission computed tomography in conjunction with computed tomography (SPECT/CT) images to explore the value of IM-SLN to guide tailored clinical target volume (CTV) delineation of postoperative prophylactic IMNI. Materials and methods: Ninety-seven patients who underwent preoperative lymphoscintigraphy by SPECT/CT and had imaging of IM-SLN were selected in this study. The imaging IM-SLNs on SPECT/CT of eligible patients were projected onto corresponding anatomical positions of a representative axial CT image. The IMN CTVs were delineated on the representative axial CT images according to the Radiation Therapy Oncology Group (RTOG) and Danish Breast Cancer Cooperative Group (DBCG) guideline, and defined as CTV_RTOG and CTV_DBCG. The location of the IM-SLNs was compared with the RTOG and DBCG guidelines of IMN target volume delineations, respectively. The intercostal space distribution of IM-SLNs was recorded. The distances from the CTV_RTOG and CTV_DBCG to the IM-SLNs were measured, respectively. Results: The total number of imaging IM-SLNs was 136. IM-SLNs were mostly found in the first intercostal space (40.4%), with 30.2, 24.3, 4.4, and 0.7% of IM-SLNs in the second, third, fourth, and fifth intercostal space, respectively. The average distance from the edge of the CTV_RTOG and the edge of CTV_DBCG to the central points of the IM-SLNs was 4.10 mm (SD, 3.3 mm) and 1.60 mm (SD, 2.6 mm), respectively (t = 16.640, P = 0.000). The average distance from the edge of CTV_RTOG and the edge of CTV_DBCG to the lateral border IM-SLN was 6.40 mm (SD, 3.5 mm) and 3.34 mm (SD, 3.3 mm), respectively (t = 19.815, P = 0.000). Only 18.4% of IM-SLN central points were included in the CTV_RTOG, and 60.3% of IM-SLN central points were included in the CTV_DBCG. When covering 90 and 100% of the IM-SLN center points, the CTV_RTOG needs to expand 8 and 15 mm, respectively, and the CTV_DBCG needs to expand 5 and 13 mm, respectively. Conclusion: Neither the RTOG nor DBCG consensus guideline about the delineation of IMN CTV was sufficient to cover 90% of IM-SLNs. For 90% coverage of IM-SLN central points, CTV_RTOG needed to be expanded by 8 mm, and CTV_DBCG needed to be expanded by 5 mm.

A Novel Device for Deep-Inspiration Breath Hold (DIBH): Results from a Single-Institution Phase 2 Clinical Trial for Patients with Left-Sided Breast Cancer

PURPOSE

To validate a novel device developed at our institution for deep inspiration breath hold (DIBH) within a phase 2 clinical trial for left-sided breast cancer and to evaluate the dosimetric benefits of its use.

METHODS AND MATERIALS

The device uses an external mechanical reference for guiding the patient to the desired breath level and gives acoustic and visual feedback to the patient and the radiation therapists, respectively. A phase 2 clinical trial was performed for its validation. The thoracic amplitude was used as a surrogate of the inspiration level. The stability, repeatability, reproducibility, and reliability of DIBH using the device were analyzed. The dosimetric parameters of the heart, the left anterior descending coronary artery, the ipsilateral lung, the contralateral breast, and the target coverage using free breathing and DIBH were compared.

RESULTS

Thirty-eight patients were included in the analysis. The maximum population value of stability and repeatability were 1.7 mm and 3.3 mm, respectively. The reproducibility mean value was 1.7 mm, and population systematic and random errors were 0.3 mm and 0.9 mm, respectively. The reliability was 98.9%. Statistically significant dose reductions were found for the heart, the left anterior descending coronary artery, and the ipsilateral lung dosimetric parameters in DIBH, without losing dose coverage to the planning target volumes.

CONCLUSIONS

The validation of the device within the phase 2 clinical trial demonstrates that it offers reliable, stable, repeatable, and reproducible breast cancer treatments in DIBH with its dosimetric benefits.

Call for a Multidisciplinary Effort to Map the Lymphatic System with Advanced Medical Imaging Techniques: A Review of the Literature and Suggestions for Future Anatomical Research

This review intends to rekindle efforts to map the lymphatic system by using a more modern approach, based on medical imaging. The structure, function, and pathologies associated with the lymphatic system are first discussed to highlight the need for more accurately mapping the lymphatic system. Next, the need for an interdisciplinary approach, with a central role for the anatomist, to come up with better maps of the lymphatic system is emphasized. The current approaches on lymphatic system research involving medical imaging will be discussed and suggestions will be made for an all-encompassing effort to thoroughly map the entire lymphatic system. A first-hand account of our integration as anatomists in the radiotherapy department is given as an example of interdisciplinary collaboration. From this account, it will become clear that the interdisciplinary collaboration of anatomists in the clinical disciplines involved in lymphatic system research/treatment still holds great promise in terms of improving clinical regimens that are currently being employed. As such, we hope that our fellow anatomists will join us in an interdisciplinary effort to map the lymphatic system, because this could, in a relatively short timeframe, provide improved treatment options for patients with cancer or lymphatic pathologies all over the world. Anat Rec, 302:1681-1695, 2019. © 2019 American Association for Anatomy.

Long-Term Pulmonary Outcomes of a Feasibility Study of Inverse-Planned, Multibeam Intensity Modulated Radiation Therapy in Node-Positive Breast Cancer Patients Receiving Regional Nodal Irradiation

PURPOSE

Multibeam intensity modulated radiation therapy (IMRT) enhances the therapeutic index by increasing the dosimetric coverage of the targeted tumor tissues while minimizing volumes of adjacent organs receiving high doses of RT. The tradeoff is that a greater volume of lung is exposed to low doses of RT, raising concern about the risk of radiation pneumonitis (RP).

METHODS AND MATERIALS

Between July 2010 and January 2013, patients with node-positive breast cancer received inverse-planned, multibeam IMRT to the breast or chest wall and regional nodes, including the internal mammary nodes (IMNs). The primary endpoint was feasibility, predefined by dosimetric treatment planning criteria. Secondary endpoints included the incidence of RP grade 3 or greater and changes in pulmonary function measured with the Common Terminology Criteria for Adverse Events version 3.0 scales, pulmonary function tests and community-acquired pneumonia questionnaires, obtained at baseline and 6 months after IMRT. Clinical follow-up was every 6 months for up to 5 years.

RESULTS

Median follow-up was 53.4 months (range, 0-82 months). Of 113 patients enrolled, 104 completed follow-up procedures. Coverage of the breast or chest wall and IMN was comprehensive (median 48.1 Gy and 48.9 Gy, respectively). The median volume of lung receiving a high dose (V20Gy) and a low dose (V5) was 29% and 100%, respectively. The overall rate of respiratory toxicities was 10.6% (11/104), including 1 grade 3 RP event (0.96%). No differences were found in pulmonary function test or community-acquired pneumonia scores after IMRT. The 5-year rates of locoregional recurrence-free, disease-free, and overall survival were 93.2%, 63.6%, and 80.3%, respectively.

CONCLUSIONS

Multibeam IMRT in patients with breast cancer receiving regional nodal irradiation was dosimetrically feasible, based on early treatment planning criteria. Despite the large volume of lung receiving low-dose RT, the incidence of grade 3 RP was remarkably low, justifying inverse-planned IMRT as a treatment modality for patients with high-risk breast cancer in whom conventional RT techniques prove inadequate.

Contouring consensus guidelines in breast cancer radiotherapy: Comparison and systematic review of patterns of failure

Adequate coverage of sites harbouring potential microscopic disease is paramount, where the clinical decision has been made to include regional lymph node radiotherapy for patients with breast cancer. This must be achieved in balance with minimising dose to normal tissues. Several international consensus guidelines detailing clinical target volumes (CTVs) are available, but there is currently no agreement as to which is most appropriate for a given clinical situation. Contouring guidelines are beneficial for routine practice and essential for clinical trial quality assurance. The aims of this study were as follows: to provide a single point of comparison of four commonly used contouring guidelines, including one used in a current Trans-Tasman Radiation Oncology Group trial; and to undertake a systematic review of existing studies which map sites of breast cancer recurrence against contouring guidelines. Two international consensus guidelines (European Society for Radiotherapy and Oncology, and Radiation Therapy Oncology Group) were compared with two clinical trial guidelines (TROG 12.02 PET LABRADOR and the Proton/Photon trial NCT02603341 RADCOMP). Comprehensive literature search for patterns of failure studies was undertaken using Embase and Pubmed. We detail the small but significant differences between the breast consensus guidelines, particularly the supraclavicular (SCF) and internal mammary chain CTVs. Seven series were found mapping recurrence patterns. These results are discussed in the context of the contouring guidelines. Several studies found the SCF CTV is the area at greatest risk of geographical 'miss'. This review will facilitate further discussion about guideline selection and modification, particularly for future clinical trials in Australia and New Zealand.

Use of helical tomotherapy in locally advanced and/or metastatic breast cancer for locoregional treatment

OBJECTIVE

Helical tomotherapy (HT) is a new promising tool whose use remains to be studied. This work assesses its impact for local irradiation in terms of side effects, as well as tumour control in locally advanced (LABC) and metastatic breast cancer (MBC).

METHODS

We retrospectively reviewed data of 66 patients with LABC and MBC. Patients received standard fractionated radiotherapy by HT, with or without concurrent systemic treatment.

RESULTS

The median age was 60 years (28-77). The median follow-up of the population was 35.9 months (10.6-95.8). For 91% of patients, HT was concomitant with systemic treatments. Three patients experienced grade 3 skin toxicity and all had concurrent 5FU-vinorelbine. One patient who was receiving concurrent treatment with trastuzumab-pertuzumab had a decreased left ventricular ejection fraction by 14%. No late cardiac or lung toxicity was observed. A clinical benefit was observed in 75% of cases. At 2 months after HT, we observed tumour regression in 7/8 patients, as following: 1 complete, 4 partial responses, and 2 stable disease. The median survival for MBC group was 64.4 months (42.6-65.8) and 21.1 (6.1-36.1) months for LABC.

CONCLUSION

This study suggests that the use of HT is well tolerated and feasible with a multimodal strategy that includes concurrent systemic treatments for patients with LABC and MBC. Advances in knowledge: The survival of LABC and MBC increases and new safe tools are needed to determine optimal strategies of treatment. To our knowledge, this is the first paper describing the use of HT for this population.

Supine MRI for regional breast radiotherapy: imaging axillary lymph nodes before and after sentinel-node biopsy

Regional radiotherapy (RT) is increasingly used in breast cancer treatment. Conventionally, computed tomography (CT) is performed for RT planning. Lymph node (LN) target levels are delineated according to anatomical boundaries. Magnetic resonance imaging (MRI) could enable individual LN delineation. The purpose was to evaluate the applicability of MRI for LN detection in supine treatment position, before and after sentinel-node biopsy (SNB). Twenty-three female breast cancer patients (cTis-3N0M0) underwent 1.5 T MRI, before and after SNB, in addition to CT. Endurance for MRI was monitored. Axillary levels were delineated. LNs were identified and delineated on MRI from before and after SNB, and on CT, and compared by Wilcoxon signed-rank tests. LN locations and LN-based volumes were related to axillary delineations and associated volumes. Although postoperative effects were visible, LN numbers on postoperative MRI (median 26 LNs) were highly reproducible compared to preoperative MRI when adding excised sentinel nodes, and higher than on CT (median 11, p  <  0.001). LN-based volumes were considerably smaller than respective axillary levels. Supine MRI of LNs is feasible and reproducible before and after SNB. This may lead to more accurate RT target definition compared to CT, with potentially lower toxicity. With the MRI techniques described here, initiation of novel MRI-guided RT strategies aiming at individual LNs could be possible.

Variability in axillary lymph node delineation for breast cancer radiotherapy in presence of guidelines on a multi-institutional platform

AIM

To quantify the variability between radiation oncologists (ROs) when outlining axillary nodes in breast cancer.

MATERIAL AND METHODS

For each participating center, three ROs with different levels of expertise, i.e., junior (J), senior (S) and expert (E), contoured axillary nodal levels (L1, L2, L3 and L4) on the CT images of three different patients (P) of an increasing degree of anatomical complexity (from P1 to P2 to P3), according to contouring guidelines. Consensus contours were generated using the simultaneous truth and performance level estimation (STAPLE) method.

RESULTS

Fifteen centers and 42 ROs participated. Overall, the median Dice similarity coefficient was 0.66. Statistically significant differences were observed according to the level of expertise (better agreement for J and E, worse for S); the axillary level (better agreement for L1 and L4, worse for L3); the patient (better agreement for P1, worse for P3). Statistically significant differences in contouring were found in 18% of the inter-center comparison. Less than a half of the centers could claim to have a good agreement between the internal ROs.

CONCLUSIONS

The overall intra-institute and inter-institute agreement was moderate. Central lymph-node levels were the most critical and variability increased as the complexity of the patient's anatomy increased. These findings might have an effect on the interpretation of results from multicenter and even mono-institute studies.

Outcome of pN0 Triple-Negative Breast Cancer with or without Lymph Node Irradiation: A Single Institution Experience

The optimal management of patients with pathologically node-negative triple-negative breast cancer (pN0 TNBC) remains unclear. We hypothesized that lymph node irradiation (LNI; internal mammary chain/periclavicular irradiation) had an impact on outcomes of pN0 TNBC. A cohort of 126 consecutive patients with pN0 TNBC treated between 2007 and 2010 at a single institute were included. All radiotherapy (breast/chest wall, ±LNI) was delivered adjuvantly, following completion of surgery ± chemotherapy. Tumors were reviewed and histologic features were described. Tissue microarrays were constructed and tumors were assessed by immunohistochemistry using antibodies against ER, PR, HER2, Ki-67, cytokeratins 5/6, 14, epidermal growth factor receptor and androgen receptor. Patients were divided into two groups for statistical analysis: LNI (LNI+) or no LNI (LNI-). We focused on disease-free survival (DFS), metastasis-free survival (MFS), and overall survival (OS). Fifty-seven and 69 patients received or not LNI, respectively. Median age was 52 (range [25-76]) and 55 (range [29-79]) in LNI+ and LNI- group (p = 0.23). LNI was associated with larger tumors (p = 0.033), central/internal tumors (33 versus 4, p < 0.01) and more chemotherapy (86% versus 59.4% p < 0.01). The median follow-up was 53.5 months. The rate of first regional relapse (associated or not with distant relapse) was low in both groups. There was no difference in 4-year DFS (82.2% versus 89.9%; p = 0.266), MFS (87.0% versus 91.1%; p = 0.286) and OS (85.8% versus 89.9%; p = 0.322) between LNI+ and LNI- group, respectively. In univariate analysis, only clinical size (T >10 mm versus ≤10 mm), histologic size (pT >10 mm versus ≤10 mm) and grade 3 (versus grade 2) were found to be significantly associated with shorter DFS. Omission of LNI in patients with pN0 TNBC does not seem to result in poorer outcome. Further studies are needed to specifically evaluate LNI in pN0 TNBC with histologic grade 3 and/or (p)T >10 mm.

MRI sequences for the detection of individual lymph nodes in regional breast radiotherapy planning

OBJECTIVE

In regional radiotherapy (RT) for patients with breast cancer, lymph node (LN) targets are delineated on CT, defined by anatomical boundaries. By identifying individual LNs, MRI-based delineations may reduce target volumes and thereby toxicity. We optimized MRI sequences for this purpose. Our aim was to evaluate the techniques for LN delineation in RT planning.

METHODS

Supine MRI was explored at 1.5 T in RT position (arms in abduction). 5 MRI techniques were optimized in 10 and evaluated in 12 healthy female volunteers. The scans included one T1 weighted (T1w), three T2 weighted (T2w) and a diffusion-weighted imaging (DWI) technique. Quantitative evaluation was performed by scoring LN numbers per volunteer and per scan. Qualitatively, scans were assessed on seven aspects, including LN contrast, anatomical information and insensitivity to motion during acquisition.

RESULTS

Two T2w fast spin-echo (FSE) methods showed the highest LN numbers (median 24 axillary), high contrast, excellent fat suppression and relative insensitivity to motion during acquisition. A third T2w sequence and DWI showed significantly fewer LNs (14 and 10) and proved unsuitable due to motion sensitivity and geometrical uncertainties. T1w MRI showed an intermediate number of LNs (17), provided valuable anatomical information, but lacked LN contrast.

CONCLUSION

Explicit LN imaging was achieved, in supine RT position, using MRI. Two T2w FSE techniques had the highest detection rates and were motion insensitive. T1w MRI showed anatomical information. MRI enables direct delineation of individual LNs.

ADVANCES IN KNOWLEDGE

Our optimized MRI scans enable accurate target definition in MRI-guided regional breast RT and development of personalized treatments.

Supraclavicular and infraclavicular lymph node delineation in breast cancer patients: a proposal deriving from a comparative study

AIMS AND BACKGROUND

Current advances in radiotherapy for breast cancer require knowledge of the anatomy of irradiated areas to minimize geographic miss and spare organs at risk. This study aimed at defining a contouring approach for supraclavicular (SC) and infraclavicular (IC) nodes after mastectomy or conservative surgery in patients with breast cancer.

METHODS AND STUDY DESIGN

In 15 patients, SC and IC nodes were contoured on computed tomography slices according to Madu et al and Dijkema et al. After analyzing relapse sites, as reported by Reed et al, our approach was defined. The 3 methods were compared in all patients, quantifying differences in contours by percentage overlap (PO).

RESULTS

In our approach, SC node delineation is similar to Madu et al in the ventral and medial landmarks, but includes the lateral SC nodes described by Dijkema et al. The lateral landmarks are the scalenus anterior and medius muscle lateral border and the clavicle. Dorsal boundaries are the scalenus anterior and medius muscle ventral and lateral surfaces and the subclavian artery ventral border. In IC node delineation, major differences emerged in cranial and dorsal limits which, in our approach, are the pectoralis minor muscle upper edge and the subclavian axillary artery ventral side. Our mean and median volumes and POs were between the other 2 methods.

CONCLUSIONS

This study contributes to standardizing draining node contouring, so as to reduce variability and minimize geographic miss.

Does ultrasound provide any added value in breast contouring for radiotherapy after conserving surgery for cancer?

BACKGROUND

Whole breast irradiation after conserving surgery for breast cancer requires precise definition of the target volume. The standard approach uses computed tomography (CT) images. However, since fatty breast and non-breast tissues have similar electronic densities, difficulties in differentiating between them hamper breast volume delineation. To overcome this limitation the breast contour is defined by palpation and then radio-opaque wire is put around it before the CT scan. To optimize assessment of breast margins in the cranial, caudal, medial, lateral and posterior directions, the present study evaluated palpation and CT and determined whether ultrasound (US) provided any added value.

METHODS

Twenty consecutive patients were enrolled after they had provided informed consent to participating in this prospective study which was approved by the Regional Public Health Ethics Committee. Palpation and US defined breast margins and each contour was marked and outlined with a fine plastic wire. Breasts were then contoured on axial CT images using the breast window width (WW) and window level (WL) (401 and 750 Hounsfield Units -HU- respectively), at which setting the plastic wires were invisible. Then, the lung window function (WW 1601 HU; WL -300 HU) was inserted to visualize the plastic wires which were used as guidelines to contour the palpable and US breast volumes. As each wire had a different diameter, both volumes were easily defined on CT slices. Results were analyzed using descriptive statistics, percentage overlap and reproducibility measures (agreement and reliability).

RESULTS

Volumes: US gave the largest and palpation the smallest. Agreement was best between palpation and CT. Reliability was almost perfect in all correlations. Extensions: Cranial and posterior were highest with US and smallest with palpation. Agreement was best between palpation and CT in all extensions except the cranial. Since strong to almost perfect agreement emerged for all comparisons, reliability was high.

CONCLUSIONS

US may be useful in defining the cranial and posterior extensions, mainly when tumours are localized there. This study demonstrates that the now standard radio-opaque wires around the palpable breast may not be needed in breast contouring.

Radiotherapy of the Lymphatic Pathways in Early Breast Cancer

International guidelines reveal substantial differences regarding indications for regional nodal irradiation (RNI). Recently, several randomized studies provided new insights and these are discussed here. Patients with 1-3 positive nodes seem to profit from RNI compared to whole-breast (WBI) or chest-wall irradiation (CWI) alone, both with regard to locoregional control and disease-free survival. Irradiation of the regional lymphatics including axillary, supraclavicular and internal mammary nodes provided a small but significant survival benefit in recent randomized trials and 1 meta-analysis. Lymph node irradiation yields comparable tumor control in comparison to axillary lymph node dissection while reducing the rate of lymph edema. Data concerning the impact of 1-2 macroscopically affected sentinel nodes or microscopic metastases on prognosis are equivocal. Recent data suggest that the current restrictive use of RNI should be scrutinized, as the hazard-benefit relation appears to shift towards an improvement of outcome.

ESTRO consensus guideline on target volume delineation for elective radiation therapy of early stage breast cancer

BACKGROUND AND PURPOSE

Delineation of clinical target volumes (CTVs) is a weak link in radiation therapy (RT), and large inter-observer variation is seen in breast cancer patients. Several guidelines have been proposed, but most result in larger CTVs than based on conventional simulator-based RT. The aim was to develop a delineation guideline obtained by consensus between a broad European group of radiation oncologists.

MATERIAL AND METHODS

During ESTRO teaching courses on breast cancer, teachers sought consensus on delineation of CTV through dialogue based on cases. One teacher delineated CTV on CT scans of 2 patients, followed by discussion and adaptation of the delineation. The consensus established between teachers was sent to other teams working in the same field, both locally and on a national level, for their input. This was followed by developing a broad consensus based on discussions.

RESULTS

Borders of the CTV encompassing a 5mm margin around the large veins, running through the regional lymph node levels were agreed, and for the breast/thoracic wall other vessels were pointed out to guide delineation, with comments on margins for patients with advanced breast cancer.

CONCLUSION

The ESTRO consensus on CTV for elective RT of breast cancer, endorsed by a broad base of the radiation oncology community, is presented to improve consistency.

Influence of Individualized Stabilization on the Consistency of Supraclavicular Fossa Positioning in Breast Radiation Therapy: A Retrospective Study

INTRODUCTION

The accurate stabilization of breast patients who are also undergoing supraclavicular fossa treatment is essential and can be challenging. Discrepancy in setup error for these patients often lies with the position of the clavicle in relationship with other anatomic structures. This study was performed to assess how individualized stabilization can improve patient's stability and reproducibility.

METHODS

Thirty patients stabilized with an individualized vacfix located on a Civco wing board (Civco Medical Solutions, Kalona, IA) were compared with 30 patients stabilized in the traditional manner on a Civco breast board (Civco Medical Solutions). Each of these patients underwent daily imaging using the Varian Clinac iX On-board Imaging System (Varian Medical Systems, Palo Alto, CA), and image mismatch data for each session were collected. Additionally, the relationship between the clavicle and vertebrae was assessed for each stabilization solution on a daily basis. Statistical analysis of this data was then performed using a mixed effects approach to take account of data grouping by patient specifically for the displacement error in each direction.

RESULTS

The use of an individualized vacfix decreased the overall systematic and random setup errors and displayed a reduction in the standard deviation of setup error. Patients positioned using breast board stabilization with the clavicle as the match method were exposed in the longitudinal direction to a systematic error of a 95% confidence interval (CI) of 2.6-4.5 mm and a random error of a 95% CI of 2.7-3.2 mm. This was significantly reduced for vacfix stabilization with a systematic error of a 95% CI of 1.2-2.3 mm and a random error of a 95% CI of 1.8-2.3 mm. These data amount to a reduction of the systematic error by 40% (P = .02) and a random error by 25% (P = .003) when using the vacfix method compared with the breast board. The data displaying the relationship between the clavicle and other anatomy within the treatment volume appear to be more consistent with the individualized vacfix approach.

CONCLUSIONS

Reproducible and consistent stabilization for the breast/supraclavicular fossa technique is vital in terms of ensuring accurate patient position. Analysis of the setup error for clavicle and spinous process matching strongly indicates a reduction in both the systematic and random setup error achieved by the vacfix. This illustrates the increased stability and reproducibility of patient positioning when an individualized vacfix is used.

Tangential vs. defined radiotherapy in early breast cancer treatment without axillary lymph node dissection: a comparative study

PURPOSE

Recent studies have demonstrated low regional recurrence rates in early-stage breast cancer omitting axillary lymph node dissection (ALND) in patients who have positive nodes in sentinel lymph node dissection (SLND). This finding has triggered an active discussion about the effect of radiotherapy within this approach. The purpose of this study was to analyze the dose distribution in the axilla in standard tangential radiotherapy (SRT) for breast cancer and the effects on normal tissue exposure when anatomic level I-III axillary lymph node areas are included in the tangential radiotherapy field configuration.

PATIENTS AND METHODS

We prospectively analyzed the dosimetric treatment plans from 51 consecutive women with early-stage breast cancer undergoing radiotherapy. We compared and analyzed the SRT and the defined radiotherapy (DRT) methods for each patient. The clinical target volume (CTV) of SRT included the breast tissue without specific contouring of lymph node areas, whereas the CTV of DRT included the level I-III lymph node areas.

RESULTS

We evaluated the dose given in SRT covering the axillary lymph node areas of level I-III as contoured in DRT. The mean VD95% of the entire level I-III lymph node area in SRT was 50.28% (range, 37.31-63.24%), VD45 Gy was 70.1% (54.8-85.4%), and VD40 Gy was 83.5% (72.3-94.8%). A significant difference was observed between lung dose and heart toxicity in SRT vs. DRT. The V20 Gy and V30 Gy of the right and the left lung in DRT were significantly higher in DRT than in SRT (p<0.001). The mean heart dose in SRT was significantly lower (3.93 vs. 4.72 Gy, p=0.005).

CONCLUSION

We demonstrated a relevant dose exposure of the axilla in SRT that should substantially reduce local recurrences. Furthermore, we demonstrated a significant increase in lung and heart exposure when including the axillary lymph nodes regions in the tangential radiotherapy field set-up.

DEGRO practical guidelines: radiotherapy of breast cancer III--radiotherapy of the lymphatic pathways

AIM

The purpose of this work is to update the practical guidelines for adjuvant radiotherapy of the regional lymphatics of breast cancer published in 2008 by the breast cancer expert panel of the German Society of Radiation Oncology (DEGRO).

METHODS

A comprehensive survey of the literature concerning regional nodal irradiation (RNI) was performed using the following search terms: "breast cancer", "radiotherapy", "regional node irradiation". Recent randomized trials were analyzed for outcome as well as for differences in target definition. Field arrangements in the different studies were reproduced and superimposed on CT slices with individually contoured node areas. Moreover, data from recently published meta-analyses and guidelines of international breast cancer societies, yielding new aspects compared to 2008, provided the basis for defining recommendations according to the criteria of evidence-based medicine. In addition to the more general statements of the German interdisciplinary S3 guidelines updated in 2012, this paper addresses indications, targeting, and techniques of radiotherapy of the lymphatic pathways after surgery for breast cancer.

RESULTS

International guidelines reveal substantial differences regarding indications for RNI. Patients with 1-3 positive nodes seem to profit from RNI compared to whole breast (WBI) or chest wall irradiation alone, both with regard to locoregional control and disease-free survival. Irradiation of the regional lymphatics including axillary, supraclavicular, and internal mammary nodes provided a small but significant survival benefit in recent randomized trials and one meta-analysis. Lymph node irradiation yields comparable tumor control in comparison to axillary lymph node dissection (ALND), while reducing the rate of lymph edema. Data concerning the impact of 1-2 macroscopically affected sentinel node (SN) or microscopic metastases on prognosis are conflicting.

CONCLUSION

Recent data suggest that the current restrictive use of RNI should be scrutinized because the risk-benefit relationship appears to shift towards an improvement of outcome.

Quality assurance of conventional non-CT-based internal mammary lymph node irradiation in a prospective Danish Breast Cancer Cooperative Group trial: the DBCG-IMN study

In 2003, the Danish Breast Cancer Cooperative Group (DBCG) initiated DBCG-IMN, a prospective study on the effect of adjuvant internal mammary lymph node radiotherapy (IMN-RT) in patients with early lymph node positive breast cancer (BC). In the study, standard DBCG IMN-RT was provided only to patients with right-sided BC. We provide estimates of doses to IMNs and organs at risk (OARs) in patients treated with the non-CT-based RT techniques used during the DBCG-IMN study.

MATERIAL AND METHODS

Five DBCG RT regimens were simulated on planning CT scans from 50 consecutively scanned BC patients, 10 in each group. Intended target volumes were chest wall or breast and regional lymph nodes ± IMNs. Field planning was conducted in the Eclipse(TM) RT treatment planning system. Subsequently, IMN clinical target volumes (CTVs) and OARs were delineated. Estimates on doses to the IMN-CTV and OARs were made.

RESULTS

IMN dose coverage estimates were consistently higher in right-sided techniques where IMN treatment was intended (p < 0.0001). Estimated doses to cardiac structures were low regardless of whether IMNs were treated or not. Post-lumpectomy patients had the highest estimated lung doses.

CONCLUSION

Overall, simulator-based treatment using the DBCG RT techniques resulted in satisfactory coverage of IMNs and acceptable levels of OAR irradiation.

Delineation of target volumes and organs at risk in adjuvant radiotherapy of early breast cancer: national guidelines and contouring atlas by the Danish Breast Cancer Cooperative Group

During the past decade planning of adjuvant radiotherapy (RT) of early breast cancer has changed from two-dimensional (2D) to 3D conformal techniques. In the planning computerised tomography (CT) scan both the targets for RT and the organs at risk (OARs) are visualised, enabling an increased focus on target dose coverage and homogeneity with only minimal dose to the OARs. To ensure uniform RT in the national prospective trials of the Danish Breast Cancer Cooperative Group (DBCG), a national consensus for the delineation of clinical target volumes (CTVs) and OARs was required.

MATERIAL AND METHODS

A CT scan of a breast cancer patient after surgical breast conservation and axillary lymph node (LN) dissection was used for delineation. During multiple dummy-runs seven experienced radiation oncologists contoured all CTVs and OARs of interest in adjuvant breast RT. Two meetings were held in the DBCG Radiotherapy Committee to discuss the contouring and to approve a final consensus. The Dice similarity coefficient (DSC) was used to evaluate the delineation agreement before and after the consensus.

RESULTS

The consensus delineations of CTVs and OARs are available online and a table is presented with a contouring description of the individual volumes. The consensus provides recommendations for target delineation in a standard patient both in case of breast conservation or mastectomy. Before the consensus, the average value of the DSC was modest for most volumes, but high for the breast CTV and the heart. After the consensus, the DSC increased for all volumes.

CONCLUSION

The DBCG has provided the first national guidelines and a contouring atlas of CTVs and OARs definition for RT of early breast cancer. The DSC is a useful tool in quantifying the effect of the introduction of guidelines indicating improved inter-delineator agreement. This consensus will be used by the DBCG in our prospective trials.

Post mastectomy linac IMRT irradiation of chest wall and regional nodes: dosimetry data and acute toxicities

BACKGROUND

Conventional post-mastectomy radiation therapy is delivered with tangential fields for chest wall and separate fields for regional nodes. Although chest wall and regional nodes delineation has been discussed with RTOG contouring atlas, CT-based planning to treat chest wall and regional nodes as a whole target has not been widely accepted. We herein discuss the dosimetric characteristics of a linac IMRT technique for treating chest wall and regional nodes as a whole PTV after modified radical mastectomy, and observe acute toxicities following irradiation.

METHODS

Patients indicated for PMRT were eligible. Chest wall and supra/infraclavicular region +/-internal mammary nodes were contoured as a whole PTV on planning CT. A simplified linac IMRT plan was designed using either integrated full beams or two segments of half beams split at caudal edge of clavicle head. DVHs were used to evaluate plans. The acute toxicities were followed up regularly.

RESULTS

Totally, 85 patients were enrolled. Of these, 45 had left-sided lesions, and 35 received IMN irradiation. Planning designs yielded 55 integrated and 30 segmented plans, with median number of beams of 8 (6-12). The integrated and segmented plans had similar conformity (1.41±0.14 vs. 1.47±0.15, p=0.053) and homogeneity indexes (0.13±0.01 vs. 0.14±0.02, p=0.069). The percent volume of PTV receiving >110% prescription dose was <5%. As compared to segmented plans, integrated plans typically increased V5 of ipsilateral lung (p=0.005), and heart (p=0.001) in patients with left-sided lesions. Similarly, integrated plans had higher spinal cord Dmax (p=0.009), ipsilateral humeral head (p<0.001), and contralateral lung Dmean (p=0.019). During follow-up, 36 (42%) were identified to have ≥ grade 2 radiation dermatitis (RD). Of these, 35 developed moist desquamation. The median time to onset of moist desquamation was 6 (4-7) weeks from start of RT. The sites of moist desquamation were most frequently occurred in anterior axillary fold (32/35), and secondly chest wall (12/35). The difference in occurrence of ≥ grade 2 RD between integrated and segmented plans was statistically insignificant (X2=0.35, p=0.55). Only 2 were found to have grade 2 radiation pneumonitis.

CONCLUSIONS

The linac IMRT technique applied in PMRT with chest wall and regional nodes as a whole PTV was dosimetrically feasible, and the treatment was proved to be well-tolerated by most patients.

A simplified CT-based definition of the supraclavicular and infraclavicular nodal volumes in breast cancer

PURPOSE

The available contouring guidelines for the supraclavicular and infraclavicular lymph nodes appeared to be inadequate for their delineation on non-enhanced computed tomography (CT) scans. For this purpose, we developed delineation guidelines for the clinical target volumes (CTV) of these lymph nodes on non-enhanced CT-slices performed in the treatment position of breast cancer.

MATERIALS AND METHODS

A fresh female cadaver study as well as delineation and an anatomical descriptions review were performed to propose a simplified definition of the supra- and infraclavicular lymph nodes using readily identifiable anatomical structures. This definition was developed jointly by breast radiologists, breast surgeons, and radiation oncologists. To validate these guidelines, the primary investigator and seven radiation oncologists (observers) independently delineated 10 different nodal CTVs. The primary investigator contours were considered to be the gold standard contours. Contour accuracy and concordance were evaluated.

RESULTS

Written guidelines for the delineation of supra- and infraclavicular lymph nodes CTVs were developed. Consistent contours with minimal variability existed between the delineated volumes; the mean kappa index was 0.83. The mean common contoured and additional contoured volumes were 84.6% and 18.5%, respectively. The mean overlap volume ratio was 0.71.

CONCLUSIONS

Simplified CT-based atlas for delineation of the supra- and infraclavicular lymph nodes for locoregional irradiation of the breast on non-enhanced CT-scan, have been developed in this study. This atlas provides a consistent set of guidelines for delineating these volumes.

[Organs at risk and target volumes: definition for conformal radiation therapy in breast cancer]

Adjuvant radiotherapy is a standard component of breast cancer treatment. The addition of radiotherapy after breast conserving surgery has been shown to reduce local recurrence rate and improve long-term survival. Accurate delineation of target volumes and organs at risk is crucial to the quality of treatment planning and delivered accomplished with innovate technologies in radiation therapy. This allows the radiation beam to be shaped specifically to each individual patient's anatomy. Target volumes include the mammary gland and surgical bed in case of breast conserving surgery, the chest wall in case of mastectomy, and if indicated, regional lymph nodes (axillary, supra- and infraclavicular and internal mammary). Organs at risk include lungs, thyroid, brachial plexus, heart, spinal cord and oesophagus. The aim of this article is to encourage the use of conformal treatment and delineation of target volumes and organs at risk and to describe specifically the definition of these volumes.

Quality indicators for breast cancer: revisiting historical evidence in the context of technology changes

Radiation therapy for breast cancer has considerably changed over the years, from simple simulator-based 2-dimensional techniques to sophisticated image-guided individualized treatments, with maximally protected normal structures. This has led to a substantial improvement in the outcome of breast cancer patients in terms of disease control, survival, and quality of life. This progress is based on clinical research and paralleled by progress in delivering sophisticated radiation treatment. Clinical trials resulted in identifying patients groups who will benefit from radiation treatment. They also stimulated the development of quality assurance tools and guidelines, which are now applied in daily clinical practice. The new technical opportunities to optimize dose distributions in patients require dedicated quality assurance measures because they may be more sensitive to variations throughout the treatment. Still, a large source of variation and uncertainty in radiation therapy remains in the definition of target volumes, which is clinically significant in terms of dosimetric target coverage as well as exposure of healthy tissues. This striving for continuous improvement of patient selection and treatment will lead to further improvement of local control while at the same time improving functional and cosmetic outcome and avoiding severe late complications, including cardiac toxicity.

[Axillary lymph node irradiation in breast cancer: state of the art]

Place of axillary radiotherapy in the management of patients with breast cancer remains debated. While the prognostic value of axillary lymph node extension has been largely demonstrated, the benefit of axillary treatment is more uncertain. Large clinical trials having demonstrated the benefit of adjuvant radiotherapy in advanced breast cancer comprised large nodal irradiation, including axillary area. Analyzing the true benefit of axillary radiotherapy is rendered difficult by heterogeneity of series, particularly when focusing on the extent of lymph node dissection. Although adjuvant axillary radiotherapy is usually recommended in patients with insufficient lymph node dissection or with bulky axillary involvement, the prognosis in these patients remains poor by metastatic evolution and such strategy exposes to increased toxicity and functional sequels. Further assessments should better define the optimal indications and the true benefit of axillary radiotherapy.

Axillary Irradiation as an Imperative Alternative to Axillary Dissection in Clinically Lymph Node-Negative but Sentinel Node-Positive Breast Cancer Patients?

At the moment, positive sentinel lymph node dissection (SLND) of the axilla is followed by axillary lymph node dissection (ALND) as standard of care. Recent data proves that omitting ALND after positive SLND in clinically lymph node-negative early stage breast cancer patients is feasible with low recurrence rates. The well known effect of radiotherapy to destroy occult tumor cells highly contributes to these results as a large extent of level I and II lymph nodes are unavoidably included in standard tangential radiation treatment fields. Reviewing the up to date published data on axillary lymph node treatment with radiotherapy, we hypothesize that full dosage coverage of level I and II of the axilla in early stage breast cancer will improve outcome and should be further evaluated.

Assessment of contralateral mammary gland dose in the treatment of breast cancer using accelerated hypofractionated radiotherapy

AIM: To measure the dose distribution, related to the treatment planning calculations, in the contralateral mammary gland of breast cancer patients treated with accelerated hypofractionated 3-dimensional conformal radiotherapy.

METHODS: Thirty-four prospectively selected female patients with right breast cancer (pN0, negative surgical margins) were treated with breast-conserving surgery. A total dose of 42.5 Gy (2.66 Gy/fraction) was prescribed; it was requested that planning target volumes be covered by the 95% isodose line. The contralateral mammary gland was defined on CT simulation. The dose received was evaluated by dose volume histograms.

RESULTS: The measured contralateral breast doses were: (1) Dose maximum: 290-448 cGy [Equivalent (Eq) 337-522 cGy]; (2) Mean dose: 45-70 cGy (Eq 524-815 cGy); and (3) Median dose: 29-47 cGy (337-547 cGy) for total primary breast dose of 42.5 Gy in 16 equal fractions. The spearman rho correlation showed statistical significance between the contralateral breast volume and maximum dose (P = 0.0292), as well as mean dose (P = 0.0025) and median dose (P = 0.046) to the breast.

CONCLUSION: Minimizing the dose to the contralateral breast has to be one of the priorities of the radiation oncologist when using short schedules because of the radiosensitivity of this organ at risk. Further study is necessary to assess the long-term clinical impact of this schedule.

Automating RTOG-defined target volumes for postmastectomy radiation therapy

PURPOSE

Consistency in defining and contouring target structures in radiation therapy (RT) is critical for highly conformal RT, for evaluating treatment plans, and for quality assurance in multi-institutional RT trials. The Radiation Therapy Oncology Group (RTOG) has published consensus guidelines for contouring targets for postmastectomy RT. To aid in contouring such structures, we evaluated the potential use of an automated contouring technique, known as deformable image registration-based breast segmentation (DEF-SEG).

METHODS AND MATERIALS

The RTOG definitions were used to contour the chest wall (CW); levels I, II, and III axillary nodes (Ax1, Ax2, Ax3); supraclavicular (SCV) nodes; internal mammary (IM) nodes; and the heart. Left-sided and right-sided templates were created. The DEF-SEG was then used to generate auto-segmented contours from the appropriate template to computed tomographic scans of 20 test cases (10 left, 10 right). To assess the accuracy of this method, those contours were manually modified as necessary to match the RTOG definitions, and the extent of the overlap was compared. The dosimetric impact of the difference in contours was then evaluated by comparing dose-volume histograms for modified and unmodified contours.

RESULTS

Mean volume-overlap ratios between the unmodified DEF-SEG-generated contours and modified contours were as follows: CW, 0.91; Ax1, 0.68; Ax2, 0.64; Ax3, 0.68; SCV node, 0.66; IM node, 0.32, and the heart, 0.93. Mean differences in volume receiving 45 Gy (V45) for the modified versus unmodified contours were as follows: CW, 2.1%; SCV node, 4.8%; Ax1, 5.1%; Ax2, 5.6%; Ax3, 3.0%; and IM node, 10.1%. Mean differences in V10 between the modified heart and the unmodified heart were 0.4% for right-sided treatment and 0.5% for left-sided treatment.

CONCLUSIONS

The DEF-SEG can be helpful for delineating structures according to the RTOG consensus guidelines, particularly for the CW and the heart. No clinically significant dosimetric differences were found between the modified and unmodified contours. The DEF-SEG may be useful for evaluating treatment plans for postmastectomy RT in multi-institutional trials.