CT localization of axillary lymph nodes in relation to the humeral head: Significance of arm position for radiation therapy planning

Dose coverage and breath-hold analysis of breast cancer patients treated with surface-guided radiotherapy

BACKGROUND

Surface-guided radiotherapy (SGRT) is used to ensure a reproducible patient set-up and for intra-fraction motion monitoring. The arm position of breast cancer patients is important, since this is related to the position of the surrounding lymph nodes. The aim of the study was to investigate the set-up accuracy of the arm of patients positioned using SGRT. Moreover, the actual delivered dose was investigated and an extensive breath-hold analysis was performed.

METHODS

84 patients who received local or locoregional breast radiation therapy were positioned and monitored using SGRT. The accuracy of the arm position, represented by the clavicle position, was studied on the anterior-posterior kV-image. To investigate the effect of changes in anatomy and patient set-up, the actual delivered dose was calculated on cone-beam CT-scans (CBCT). A deformable registration of the CT to the CBCT was applied to deform the structures of the CT onto the CBCT. The minimum dose in percentage of the prescribed dose that was received by 98% of different CTV volumes (D98) was determined. An extensive breath-hold analysis was performed and definitions for relevant parameters were given.

RESULTS

The arm position of 77 out of 84 patients in total was successful, based on the clavicle rotation. The mean clavicle rotation was 0.4° (± 2.0°). For 89.8% of the patients who were irradiated on the whole-breast D98 was larger than 95% of the prescribed dose (D98 > 95%). D98 > 95% applied for 70.8% of the patients irradiated on the chest wall. Concerning the lymph node CTVs, D98 > 95% for at least 95% of the patients. The breath-hold analysis showed a mean residual setup error of - 0.015 (± 0.90), - 0.18 (± 0.82), - 0.58 (± 1.1) mm in vertical, lateral, and longitudinal direction, respectively. The reproducibility and stability of the breath-hold was good, with median 0.60 mm (95% confidence interval (CI) [0.66-0.71] mm) and 0.20 mm (95% CI 0.21-0.23] mm), respectively.

CONCLUSIONS

Using SGRT we were able to position breast cancer patients successfully, with focus on the arm position. The actual delivered dose calculated on the CBCT was adequate and no relation between clavicle rotation and actual delivered dose was found. Moreover, breath-hold analysis showed a good reproducibility and stability of the breath-hold. Trial registration CCMO register NL69214.028.19.

Standardization of upper limb exercises to improve radiation therapy for breast cancer, a conceptual literature review

INTRODUCTION

Many patients with breast cancer are left with upper arm mobility dysfunction following surgery. Despite the beneficial effects of upper limb exercises on shoulder dysfunction, radiation therapists still do not widely encourage patients to participate in arm exercises after surgery. This conceptual literature review synthesizes evidence on how patients with breast cancer that participate in upper limb exercises after surgery have improved arm mobility which could result in a more consistent arm position during radiation therapy.

METHODS

A literature search was performed in the PubMed, Athabasca University Library, and Google Scholar databases to identify articles that evaluated the effect of upper limb exercises on patients' arm mobility and range of motion after breast cancer surgery, and the impact of arm position on anatomy during radiation therapy. Sixteen studies were included in the conceptual review synthesis.

RESULTS

The studies were heterogeneous in terms of the utilized exercise methods and the upper limb related outcomes measured. Twelve studies demonstrated that upper arm exercises are an effective intervention in restoring arm mobility and decreasing pain in women with breast cancer. Additionally, four studies showed that differences in arm rotation affect the breast region's anatomy, which could result in set-up errors during radiation therapy.

CONCLUSION

The effectiveness of radiation therapy for breast cancer treatment relies on women to reproduce their shoulder position each day. Any inability to replicate the arm position due to mobility issues can affect the accuracy of the dose delivered and, ultimately, the treatment outcome. Therefore, upper limb exercises should be recommended by radiation therapists to their patients before or during radiation therapy to improve patient comfort and the accuracy of treatment. Additionally, upper limb exercise standards need to be developed for patients with breast cancer and implemented by radiation therapists.

Modelling level I Axillary Lymph Nodes depth for Microwave Imaging

PURPOSE

Patient-specific information on the depth of Axillary Lymph Nodes (ALNs) is important for the development of new diagnostic imaging technologies, e.g. Microwave Imaging (MWI), aiming to assess the diagnosis of ALNs during breast cancer staging. Studies about ALNs depth have been presented for treatment planning, but they lack information on sample size and usability of the data to infer the depth of ALNs. The aim of this study was to create a mathematical model that can be used to predict a depth interval where level I ALNs are likely to be located.

METHODS

We extracted biometric features of 98 patients who underwent breast Magnetic Resonance Imaging (MRI) to train two types of regression models. We then tested different combination of features to predict ALNs depth and found the best predictor. The final prediction models were then implemented in an algorithm used for MWI and tested with anthropomorphic phantoms of the axillary region.

RESULTS

Body Mass Index (BMI) was the feature with best performance to predict ALNs depth with coefficient of determination (R²) ranging from 0.49 to 0.55 and Root Mean Squared Error (RMSE) ranging from 0.68 to 0.91 cm. The proposed model showed satisfactory results in microwave images of patients with different BMIs.

CONCLUSIONS

The presented results contribute to the development of reconstruction algorithms for new imaging technologies and to the assessment of ALNs in other medical applications.

How do I deal with the axilla in patients with a positive sentinel lymph node?

OPINION STATEMENT

Optimal management of the axilla in a patient with a positive sentinel node biopsy is not yet defined.These patients usually have Breast Conserving Surgery and receive adjuvant systemic therapy and whole breast radiation.Treatment options for the axilla include: no further surgery with or without radiation completion axillary nodal dissection with or without radiation Radiation options in addition to whole breast radiation include axillary and supraclavicular nodal irradiation regional nodal irradiationincludes supraclavicular and internal mammary nodes Completion axillary dissection has been standard practice in patients with positive sentinel nodes. the number of involved nodes provides prognostic information. theoretically improves local control, but may be obviated by systemic chemotherapy. but avoidance of dissection may not adversely affect locoregional control or survival. dissection has significant morbidity so safe avoidance is desirable. There is little worldwide concordance on the use of radiation: whole breast radiation (commonly used after breast conserving surgery) may radiate the lower axilla supraclavicular radiation is most commonly recommended for patients with four or more nodes but may confer a survival benefit on patients with lower risk disease. adding nodal irradiation reduces local recurrence with only modest toxicity. Adjuvant systemic therapy provides a survival benefit for patients with nodal disease. Most will receive cytostatic chemotherapy containing an anthracycline and a taxane. Hormone therapy is appropriate for estrogen receptor positive disease. The extent to which systemic therapy controls microscopic nodal disease is unknown. Node positive patients should generally receive adjuvant chemotherapy.A small group of patients benefit from specific nodal therapy. Further studies are needed to better identify these patients.

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.

Effects of variable placement of superior tangential/supraclavicular match line on dosimetric coverage of level III axilla/axillary apex in patients treated with breast and supraclavicular radiotherapy

PURPOSE

To determine the differences in dosimetric coverage of the Level III axillary node target as a function of the superior tangential/supraclavicular match line in breast cancer patients undergoing with tangential breast and supraclavicular fossa radiotherapy.

METHODS AND MATERIALS

The data from 20 consecutive breast cancer patients who were treated with breast conservation surgery and Level I and II axillary dissection followed by radiotherapy to the undissected Level III axilla/supraclavicular fossa were retrospectively analyzed. The nodal volumes were delineated from the computed tomography simulation data set. Three composite treatment plans were generated for each patient according to the placement of the match line.

RESULTS

Coverage of the contoured Level III/axillary apex varied significantly with respect to the ipsilateral clavicular head, depending on the placement of the superior tangential/supraclavicular match line. The mean volume of the Level III/axillary apex covered by the 90% isodose line (45 Gy) was 100% for caudal placement of the match line, significantly greater than the 92% for intermediate placement (bisecting the clavicular head; p = 0.001) and the 68% for cranial placement with respect to the clavicular head (p < 0.001).

CONCLUSION

Placement of the superior tangential/supraclavicular match line caudal to the clavicular head results in statistically improved dosimetric coverage of the Level III axilla/axillary apex in breast cancer patients undergoing tangential/supraclavicular radiotherapy.

Radiation Therapy as Primary and Adjuvant Treatment for Local and Regional Melanoma

Background

The role of radiation therapy as primary and adjuvant therapy for localized or locally advanced melanoma is controversial.

Methods

To develop evidence-based guidelines, PubMed was searched using the keywords melanoma AND (radiation OR radiotherapy). These references were reviewed and the relevant articles selected. The articles were then reviewed for further references. Because of the paucity of prospective or randomized trials, no attempt was made to classify the quality of the results.

Results

No phase III trials of nodal irradiation for prevention of regional recurrence are available. A phase III trial is being completed by the Tasman Radiation Oncology Group. A phase II trial has been completed by the group. Multiple retrospective series have been published. The available data appear to confirm that nodal radiation therapy is effective in preventing nodal recurrence. No dose response or fraction size response was found. According to generally accepted guidelines, radiation therapy should be offered for patients who have nodes greater than 3 cm, more than 3 involved nodes, or extracapsular extension. For radiation therapy for the treatment of metastatic disease, a phase III trial showed that 50 Gy in 2.5-Gy fractions was as effective as 32 Gy in 8-Gy fractions, with 25% complete remission and 35% partial remission. In contrast, the retrospective studies support that larger fraction sizes, at least 4 Gy, are more effective.

Conclusions

Adjuvant nodal irradiation appears to be effective for the prevention of nodal recurrence. Radiation therapy can also be effective for treatment of local disease, if surgery is not an option.

Regional lymph node irradiation in breast cancer

A recent meta-analysis, published by the Early Breast Cancer Trialists' Collaborative Group, demonstrated a clear survival advantage of post-operative radiotherapy on the breast, chest wall and regional lymphatics in node-positive disease. The extensive target volume in locoregional irradiation of breast cancer, in close proximity to the heart and lungs, complicates treatment planning. The breast or chest wall fields need to match the supraclavicular/axillary and parasternal fields, at the subclavicular and parasternal matchline, respectively. Dose distribution near the junction area is often inhomogeneous, and under- and over-dosage can occur, which can lead to recurrences and complications. This paper describes briefly the indications, complications and target localization concerning regional lymph node radiotherapy and discusses more extensively the advantages and disadvantages of the most frequently used treatment techniques.