Regional recurrence after adjuvant breast cancer radiotherapy is not due to insufficient target coverage

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.

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.

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.

A multidisciplinary view of mastectomy and breast reconstruction: Understanding the challenges

The current review paper was written in collaboration with breast cancer surgeons from the European Breast Cancer Research Association of Surgical Trialists (EUBREAST), a breast pathologist from the Danish Breast Cancer Group (DBCG), and representatives from the European SocieTy for Radiotherapy & Oncology (ESTRO) breast cancer course. Herein we summarize the different mastectomies and reconstruction procedures and define high-risk anatomical areas for breast cancer recurrences, to further specify the challenges in the surgical procedure, histopathological evaluation, and target volumes in case of postmastectomy irradiation, as recommended by the ESTRO guidelines according to the surgical procedure. The paper has original figures and illustrations for all disciplines for in-depth understanding of the differences between the procedures.

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Mastectomy techniques and reconstruction evolved to improve cosmetic outcomes.

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Different techniques maybe associated with different amount of residual breast tissue.

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More data is needed to estimate who are the patients at risk for residual disease or recurrence.

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Multidisciplinary work needed to individualise treatment for optimal oncological outcomes while maintaining the significant improvements in achieving better cosmesis for these patients.

[Prophylactic nodal radiotherapy for breast cancer]

Adjuvant radiotherapy is a key treatment in early-stage breast cancer. The meta-analysis by the Early Breast Cancer Trialist's Collaborative Group (EBCTCG) has demonstrated a decreased risk of locoregional relapse and death after whole-breast radiotherapy. Prophylactic lymph nodes irradiation in breast cancer has also proven to be beneficial in several therapeutic trials. At a time when three-dimensional conformal radiotherapy has become the standard procedure and with the development of intensity-modulated radiation therapy, defining nodal volumes is essential and practices should be harmonized to assess and compare the efficiency and toxicity of radiotherapy. Furthermore, the indication of lymph nodes irradiation has to take into account the risk/benefit balance as expanding the irradiated volume can increase radio-induced toxicity. Selection of patients receiving this treatment is essential. The aim of this update is to define nodal volumes, to precise the indications of their irradiation and to present the expected benefits as well as the potential side effects.

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.

Loco-regional morbidity after breast conservation and axillary lymph node dissection for early breast cancer with or without regional nodes radiotherapy, perspectives in modern breast cancer treatment: the Skagen Trial 1 is active

BACKGROUND

Axillary lymph node dissection (ALND) and adjuvant radiotherapy (RT) in early breast cancer are associated with a risk of morbidity, including lymphedema and impaired shoulder mobility. The aim of this study was to evaluate loco-regional morbidity after breast conserving surgery (BCS), ALND, taxane-based chemotherapy and whole breast irradiation (WBI) with or without regional nodes RT.

MATERIAL AND METHODS

Eligible patients had BCS and ALND from 2007 to 2012 followed by adjuvant taxane-based chemotherapy and if indicated, trastuzumab and endocrine treatment. The RT consisted of WBI and regional nodes RT in case of ≥ pN1 disease (group 1) and WBI only in case of pN0-1(mic) disease (group 2). The dose was 50 Gy in 25 fractions. The patients were invited to participate in a cross-sectional study evaluating morbidity.

RESULTS

Of the 347 eligible patients, 277 patients (79%) accepted the invitation. Of these, 185 patients (67%) belonged to group 1 and 92 patients (33%) to group 2. The median time from RT to evaluation of morbidity was 3.3 years (group 1) and 4.3 years (group 2). In group 1, 34 patients (18%) and in group 2, 15 patients (16%) had ≥2 cm enlargement in circumference of ipsilateral upper or lower arm (p = .67). The frequence of impairment of ipsilateral shoulder abduction to ≤120° was 3% in both groups and of shoulder flexion to ≤120° was 1% and 2% (group 1 versus 2). No difference in patient reported outcome measure (PROM) data regarding heaviness or enlargement of ipsilateral upper and lower arm or mobility and sensory disturbances.

CONCLUSION

The risk of lymphedema was low in patients after ALND and not related to use of regional nodes RT. Impairment of shoulder function was rare, and no differences in PROM were detected regarding use or not of regional nodes RT.

[Prophylactic axillary radiotherapy for breast cancer]

Adjuvant radiotherapy, after breast conserving surgery or mastectomy for breast cancer, improves overall survival while decreasing the risk of recurrence. However, prophylactic postoperative radiotherapy of locoregional lymph nodes for breast cancer, particularly of the axillary region, is still controversial since the benefits and the risks due to axillary irradiation have not been well defined. To begin with, when performing conformal radiotherapy, volume definition is crucial for the analysis of the risk-benefit balance of any radiation treatment. Definition and contouring of the axillary lymph node region is discussed in this work, as per the recommendations of the European Society for Radiotherapy and Oncology (ESTRO). Axillary recurrences are rare, and the recent trend leads toward less aggressive surgery with regard to the axilla. In this literature review we present the data that lead us to avoid adjuvant axillary radiotherapy in pN0, pN0i+ and pN1mi patients even without axillary clearance and to perform it in some other situations. Finally, we propose an update about the potential toxicity of adjuvant axillary irradiation, which is essential for therapeutic decision-making based on current evidence, and to guide us in the evolution of our techniques and indications of axillary radiotherapy.

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.