Relationship of sentinel and axillary level I-II lymph nodes to tangential fields used in breast irradiation

PURPOSE: To evaluate the volume of nodal irradiation associated with breast-conserving therapy, we defined the anatomic relationship of sentinel lymph nodes and axillary level I and II lymph nodes in patients receiving tangential breast irradiation. METHODS AND MATERIALS: A retrospective analysis of 65 simulation fields in women with breast cancer treated with sentinel lymph node surgery and 39 women in whom radiopaque clips demarcated the extent of axillary lymph node dissection was performed. We measured the relationship of the surgical clips to the anatomic landmarks and calculated the percentage of prescribed dose delivered to the sentinel lymph node region. RESULTS: A cranial field edge 2.0 cm below the humeral head the sentinel lymph node region was included or at the field edge in 95% of the cases and the entire extent of axillary I and II dissection in 43% of the axillary dissection cases. In the remaining 57%, this field border encompassed an average of 80% of cranial/caudal extent of axillary level I and II dissection. In 98.5% of the cases, all sentinel lymph nodes were anterior to the deep field edge and 71% were anterior to the chest wall-interface, whereas 61% of the axillary dissection cohort had extension deep to the chest wall-lung interface. If the deep field edge had been set 2 cm below the chest wall-lung interface, the entire axillary dissection would have been included in 82% of the cases, and the entire sentinel lymph node would have been covered with a 0.5-cm margin. The median dose to the sentinel lymph node region was 98% of the prescribed dose. CONCLUSIONS: By extending the cranial border to 2 cm below the humeral head and 2 cm deep to the chest wall-lung interface, the radiotherapy fields used to treat the breast can include the sentinel lymph node region and most of axillary levels I and II.     

Evaluation of level I and II axillary nodes included in the standard breast tangential fields and calculation of the administered dose: results of a prospective study

PURPOSE: To evaluate if Level I and II axillary nodes are included in the standard breast tangential fields, and to calculate the dose administered. METHODS AND MATERIALS: In 35 patients treated with conservative surgery and axillary dissection, three clips were surgically positioned: one at the beginning of Level I, one between Level I and II, and another at the end of Level II. The breast was irradiated with two tangential fields. On simulation films, the volume between the clips was scored as "entirely included" or "not entirely included" in the treatment fields. Computed tomography (CT) scans were performed; CT data were imported into a treatment planning system, and three-dimensional plans were devised. Axillary Levels I and II were delineated on CT slices on the basis of anatomic landmarks. Fields and isodose curves previously obtained were superimposed to calculate the dose administered to the first two axillary node levels and to 90% of both volumes. RESULTS: On X-rays, the volume between clips corresponding to Level I was completely included in the medial field in 66.7% of cases and in the lateral field in 63.7% of cases, whereas the volume of Level II was entirely included in the medial field in 54.5% of cases and in the lateral field in 45.4% of cases. The median dose administered to Level I and II was 38.58 Gy +/- 11.01 (range 3.46-47.14) and 20.65 Gy +/- 14.07 (range 0.95-38.94), respectively. The median dose to 90% of both volumes of Level I and II was 6.75 Gy +/- 14.01 (range 1.9-39) and 1.75 Gy +/- 9.72 (range 0.8-29), respectively. CONCLUSION: The standard tangential fields do not entirely include Levels I and II axillary nodes.     

Evaluation of novel modified tangential irradiation technique for breast cancer patients using dose-volume histograms

PURPOSE: We have previously reported that entire axillary lymph node regions could be irradiated by the modified tangential irradiation technique (MTIT). In this study, MTIT was compared with a conventional irradiation technique (CTIT) using dose-volume histograms to verify how adequately MTIT covers the breast and axillary lymph node region and the extent to which it involves the lung and heart. METHODS AND MATERIALS: Forty-four patients with early-stage breast cancer were treated by lumpectomy, axillary dissection, and postoperative radiotherapy. Twenty-two patients were treated with MTIT and 22 with CTIT. In 25 patients, the breast tumor was on the left and in 19 on the right. During axillary dissection, surgical clips were left as markers at the border of the axillary lymph node region. MTIT was planned by setting the dorsal edge of the radiation field on a lateral-view simulator film at the dorsal edge of the humeral head and the cranial edge of the radiation field at the caudal edge of the humeral head. CTIT was planned to ensure radiation of the breast tissue without considering the axillary region. In this study, all patients underwent computed tomography, and the CT data were transmitted on-line to a radiotherapy planning system, in which the dose-distribution computed tomography images and dose-volume histograms were calculated by defining the breast, axillary region (levels I, II, and III), lung, and heart region. RESULTS: Dose-volume histogram analysis demonstrated that breast tissue was radiated with an 86.5-100% volume (median 96.5%) by MTIT and an 83-100% volume (median, 95%) by CTIT at >95% of the isocenter dose. The axillary lymph node regions at Levels I, II, and III were irradiated with 84-100% (median, 94.5%), 59-100% (median, 89%), and 70-100% (median, 89.5%) volumes, respectively, by MTIT and with 2-84% (median, 38%), 0-53% (median, 15%), and 0-31% (median, 0%) volumes, respectively, by CTIT at >70% of the isocenter dose. The ipsilateral lung was irradiated with a 5-22% volume (median, 11.5%) by MTIT and 5-15% volume (median 9%) by CTIT at >90% of the isocenter dose. In all 25 left-sided breast cancer patients, the volumes irradiated with an 80% isocenter dose were <30 cm(3). CONCLUSION: The results of our study demonstrated that the breast tissue was sufficiently irradiated with both CTIT and MTIT planning, the axillary lymph node areas irradiated by MTIT were much wider than those irradiated by CTIT at all levels, and the lung and heart volumes irradiated by MTIT were small.     

The modified tangential irradiation technique for breast cancer: how to cover the entire axillary region

PURPOSE: The two-portal tangential irradiation technique has usually been applied to breast cancer patients after breast-conserving surgery (1, 2) and is expected to irradiate the axillary lymph node region to some extent (3). We investigated the range of the axillary region covered by this technique and tried to devise an optimal irradiation technique (modified tangential irradiation) that would cover the axillary lymph node region properly. METHODS AND MATERIALS: We checked the status of the surgical clips left at axillary lymph node sites by reviewing the simulator films and planning CT scans of 63 patients who underwent axillary dissection of level I, I-II, or I-III lymph nodes. Then we created the modified tangential irradiation technique and applied this technique to 16 patients and checked the irradiation volume by CT scans. RESULTS: We found that all of the surgical clips on lateral-view simulator films were on the ventral side of the dorsal edge line of the humeral head. All but one clip were on the caudal side of the caudal edge line of the humeral head. Accordingly, it is possible to irradiate almost all axillary lymph node regions by setting the dorsal edge of the irradiation field on lateral-view simulator films at the dorsal edge of the humeral head and the cranial edge at the caudal edge of the humeral head. CONCLUSIONS: All breast tissue and the entire axillary lymph node region can be covered by the modified tangential irradiation technique without increasing the lung volume irradiated.     

Are the axillary lymph nodes treated by standard tangent breast fields?

BACKGROUND AND OBJECTIVES: With the increasing use of sentinel lymph node biopsy, a growing proportion of women with early-stage invasive breast cancer are undergoing breast conserving surgery without a formal axillary lymph node dissection. A frequent question raised is whether the level I-II axillary lymph nodes are treated with standard breast tangent fields. In an attempt to answer this question, surgical clips placed at the time of the level I-II axillary lymph node dissection were used as a surrogate for the location of the nodes and the simulator films for tangent fields of 45 patients were analyzed. METHODS: Study criteria were as follows: five or more clips placed in the axilla, and all clips and the humeral head visualized on the medial tangent film. Clips were scored as "in" or "out" of the tangent field, as defined by the delineator wires. All technical parameters were analyzed to determine whether any reproducible techniques would consistently include all of the clips and, hypothetically, the axillary nodes at levels I and II. RESULTS: All clips were included in the medial tangent breast radiation field in only 38% (17 of 45) of cases. CONCLUSIONS: The standard, two-field tangent breast fields do not reliably encompass the all level I-II axillary lymph nodes as defined by this study, but some of the nodes were treated in all 45 cases.     

An improved technique for breast cancer irradiation including the locoregional lymph nodes

Purpose: To find an irradiation technique for locoregional irradiation of breast cancer patients which, compared with a standard technique, improves the dose distribution to the internal mammary–medial supraclavicular (IM-MS) lymph nodes. The improved technique is intended to minimize the lung dose and reduce the dose to the heart.

Methods and Materials: The standard technique consists of an anterior mixed electron/photon IM-MS field. In the improved technique, an oblique electron and an oblique asymmetric photon field are combined to irradiate the IM lymph nodes. To irradiate the MS lymph nodes, a combination of an anterior electron and an anterior asymmetric photon field is used. For both the standard and the improved technique, tangential photon fields are used to irradiate the breast. Three-dimensional (3D) treatment planning was performed for 8 patients with various breast sizes for these two techniques. Dose–volume histograms (DVHs) and normal tissue complication probabilities (NTCPs) were compared for both techniques. The field dimensions and energy of the standard technique were determined at simulation, whereas for the improved technique the fields were designed by CT-based treatment planning.

Results: The dose in the breast planning target volume was essentially the same for both techniques. For the improved technique, combined with 3D localization information, an improvement in the IM-MS planning target coverage is seen. The volume within the 95% isodose surface was on average 25% (range, 0–64%) and 74% (range, 43–90%) for the standard and improved technique, respectively. The heart generally receives less dose with the improved technique. However, sometimes a small but acceptable increase in lung dose is found.

Conclusion: The improved technique, combined with localization information of the IM-MS lymph nodes, greatly improves the dose distribution in the planning target volume for a large group of patients without significantly increasing the dose to organs at risk.     

乳房保留术后野中野正向调强全乳房照射的腋窝淋巴结剂量学研究

目的 研究早期乳腺癌患者保乳术后采用野中野正向调强技术进行单纯乳房照射时各站腋窝淋巴结剂量分布及影响因素。方法 37例乳腺癌患者保乳术后采用“野中野”技术照射乳房,在定位CT图像上勾画患侧第Ⅰ、Ⅱ、Ⅲ站和胸肌间淋巴结靶区,并勾画腋静脉,在三维放疗计划软件上逐站分析其所接受的剂量。配对t检验分析影响腋窝淋巴结剂量分布的因素。结果 在全乳PTV处方剂量50 Gy分25次情况下,第Ⅰ、Ⅱ、Ⅲ站和胸肌间淋巴结被95%处方剂量所包括体积比平均值分别为34.7%、6.1%、0.4%和39.6%,D_mean分别为30.8、15.7、5.0 Gy和28.8 Gy;腋静脉以下和以上淋巴结区域被95%处方剂量包括的体积比为45.6%和0.7%,D_mean为38.2 Gy和6.7 Gy。乳房照射野的上界距离肱骨头的距离是影响腋静脉以下淋巴结区域D_mean的唯一有意义因素(P=0.037)。结论 全乳正向调强野中野技术对腋静脉以下腋窝淋巴结的实际照射剂量是不可忽略的,必须在分析保乳术后腋窝淋巴结控制率时予以考虑。     

Analysis of axillary coverage during tangential radiation therapy to the breast

PURPOSE: To evaluate the percent of the prescribed radiation dose to the breast delivered to the axillary tissue and to evaluate the volume of the axilla receiving 95% of the prescribed dose with normal and with high tangential fields. METHODS AND MATERIALS: Computed tomographic scan images with 5-mm sections were retrospectively analyzed for 35 patients who had undergone three-dimensional (3D) planning for whole-breast radiation. The axillary nodal region was identified and divided into Levels I to III and Rotter's nodes (RN). Digitally reconstructed radiographs were created, and two plans were developed: (a) the standard clinical opposed tangential irradiation fields and (b) the high-tangential irradiation fields. Axillary coverage was examined by use of dose-volume histograms (DVH), and the average coverage for the four nodal groups was obtained. RESULTS: The data show that with the standard tangential irradiation fields, the average dose delivered to Levels I, II, III, and RN is 66% (standard deviation, or SD = 13%), 44% (SD = 18%), 31% (SD = 20%), and 70% (SD = 19%) of the prescribed dose, respectively. The coverage increases to 86% (SD = 9%), 71% (SD = 19%), 73% (SD = 17%), and 94% (SD = 8%) of the prescribed dose, respectively, for Levels I, II, III, and RN when the high tangential irradiation fields are used. 51% of Level I, 26% of Level II, and 15% of Level III receive 95% of the prescribed dose with normal tangents. The volume increases to 79%, 51%, and 49% of Levels I, II, and III, respectively, with high tangents. CONCLUSION: The tangential fields designed to treat only the breast do not adequately cover the axillary region and, therefore, cannot be relied upon for prophylactic therapy of the axilla. The high tangential irradiation fields increase the dosages received by the axillary region, but the average dosages received by the lower axillary regions are still less than 90% of the prescribed dose.     

Evaluation of breast sentinel lymph node coverage by standard radiation therapy fields

BACKGROUND: Biopsy of the breast sentinel lymph node (SLN) is now a standard staging procedure for early-stage invasive breast cancer. The anatomic location of the breast SLN and its relationship to standard radiation fields has not been described. METHODS AND MATERIALS: A retrospective review of radiotherapy treatment planning data sets was performed in patients with breast cancer who had undergone SLN biopsy, and those with a surgical clip at the SLN biopsy site were identified. The location of the clip was evaluated relative to vertebral body level on an anterior-posterior digitally reconstructed radiograph, treated whole-breast tangential radiation fields, and standard axillary fields in 106 data sets meeting these criteria. RESULTS: The breast SLN varied in vertebral body level position, ranging from T2 to T7 but most commonly opposite T4. The SLN clip was located below the base of the clavicle in 90%, and hence would be excluded from standard axillary radiotherapy fields where the inferior border is placed at this level. The clip was within the irradiated whole-breast tangent fields in 78%, beneath the superior-posterior corner multileaf collimators in 12%, and outside the tangent field borders in 10%. CONCLUSIONS: Standard axillary fields do not encompass the lymph nodes at highest risk of containing tumor in breast cancer patients. Elimination of the superior-posterior corner MLCs from the tangent field design would result in inclusion of the breast SLN in 90% of patients treated with standard whole-breast irradiation.     

Evaluation of a standard breast tangent technique: a dose-volume analysis of tangential irradiation using three-dimensional tools

PURPOSE: A thorough dose-volume analysis of a standard tangential radiation technique has not been published. We evaluated the adequacy of a tangential radiation technique in delivering dose to the breast and regional lymphatics, as well as dose delivered to underlying critical structures. METHODS AND MATERIALS: Treatment plans of 25 consecutive women with breast cancer undergoing lumpectomy and adjuvant breast radiotherapy were studied. Patients underwent two-dimensional (2D) treatment planning followed by treatment with standard breast tangents. These 2D plans were reconstructed without modification on our three-dimensional treatment planning system and analyzed with regard to dose-volume parameters. RESULTS: Adequate coverage of the breast (defined as 95% of the target receiving at least 95% of the prescribed dose) was achieved in 16 of 25 patients, with all patients having at least 85% of the breast volume treated to 95% of the prescribed dose. Only 1 patient (4%) had adequate coverage of the Level I axilla, and no patient had adequate coverage of the Level II axilla, Level III axilla, or the internal mammary lymph nodes. CONCLUSION: Three-dimensional treatment planning is superior in quantification of the dose received by the breast, regional lymphatics, and critical structures. The standard breast tangent technique delivers an adequate dose to the breast but does not therapeutically treat the regional lymph nodes in the majority of patients. If coverage of the axilla or internal mammary lymph nodes is desired, alternate beam arrangements or treatment fields will be necessary.     

Internal mammary node coverage: an investigation of presently accepted techniques

PURPOSE: Recent publications have generated a renewed interest in regional nodal treatment to include the ipsilateral supraclavicular and internal mammary nodes (IMN). The purpose of this study is to evaluate three presently accepted treatment techniques for coverage of the intact breast and ipsilateral lymph node regions and to construct recommendations regarding the utilization of these techniques. METHODS AND MATERIALS: Anatomic data were obtained from five randomly selected patients with computerized tomography (CT) in treatment position. Three patients presented with cancer of the left breast and two with cancer of the right. Using the Pinnacle 3-D planning system, normal tissue volumes of breast, ipsilateral lung, heart, sternum, and the IMN target were delineated for each patient. Three accepted techniques used to treat ipsilateral breast, internal mammary and supraclavicular nodes (extended tangents, 5-field, partly wide tangents) were configured and compared to a supraclavicular field matched to standard tangential fields. A dosage of 50 Gy in 25 fractions was prescribed to the target volume. Dose-volume histograms (DVH) were generated and analyzed with regard to target volume coverage and lung/heart volumes treated. RESULTS: All of the treatment techniques covering IMN include at least 10% more lung and heart volume than that covered by standard tangential fields. The relative lung and heart volumes treated with each technique were consistent from patient to patient. The 5-field technique clearly treats the largest volume of normal tissue; however, most of this volume receives less than 50% of the dose prescribed. The percent of heart and ipsilateral lung treated to 20 Gy, 30 Gy, and 40 Gy have been calculated and compared. Due to the increase in chest wall thickness and depth of IMN superiorly, complete coverage was not achieved with any technique if the IMN target extended superiorly into the medial supraclavicular field where dose fall-off resulted in a significant underdosing at depth. For the same anatomic reasons, the 5-field technique underdosed 10-15% of the IMN target volume in 4 of the 5 cases. This technique also yielded a greater dose heterogeneity, which was not seen with the other techniques evaluated and correlated with the change of anterior chest wall thickness. CONCLUSIONS: Anatomic variation in chest wall thickness and IMN depth strongly suggests the routine use of multislice CT planning to ensure complete coverage of the target volume and optimal sparing of normal tissue. All of the techniques can be constructed to look acceptable at central axis. To cover the superior most aspect of the IMN chain either high tangential fields, a supraclavicular field photon beam of energy >6 MV, or an AP/PA supraclavicular setup should be considered. The 5-field technique has the most difficulty in compensating for the increased depth of the IMN in the superior aspect of the tangent fields with up to +/-40% variation of the dose noted in isolated areas within the target volume. Based on our evaluation, the partly wide tangent technique offers many advantages. It provides optimal coverage of the target volume, reduces coverage of normal tissue volumes to an acceptable level, and is easily reproducible with a high degree of dose homogeneity throughout the target.     

Towards individualised radiotherapy for Stage I seminoma.

BACKGROUND AND PURPOSE: Adjuvant radiotherapy is currently standard treatment of Stage I seminoma (SOS). The use of computerised tomogram (CT) planning is compared with traditional planning for greater treatment individualisation. MATERIAL AND METHODS: Two plans were generated for each of 10 patients: one using traditional rectangular para-aortic fields, and one using conformal fields. The primary target volume compared was the dosimetric coverage of the inferior vena cava and aorta. RESULTS: The dosimetric analysis of traditional plans showed that they provided reasonable dosimetric coverage of the CTV. However, if 1cm is used for uncertainty based on nodal coverage then the periphery of the PTV could be significantly under-dosed. The CT based plan delivered improved dosimetry to the vessel PTV compared with the traditional field (CT D 95=24.7 Gy, traditional D 95=23.6 Gy, P=0.002). CT-based plans were significantly wider than traditional plans (CT=11.8 cm, traditional=9 cm, P=0.002). The CT plan tended to irradiate relatively small volumes of the kidneys to higher doses. CONCLUSIONS: Traditional para-aortic fields may deliver suboptimal dosimetry to an anatomically defined PTV. Our CT-based fields tend to be wider than traditional fields, and provide improved dosimetry to vessels based target volumes. Given that traditional fields are often delivering significantly less than the prescribed dose to the target volume, and that marginal relapses cause a high proportion of treatment failure, there is a suggestion that CT-based plans may avoid under-dosage and geographical miss sometimes seen with traditional plans.     

乳腺癌保乳术后全乳逆向IMRT对腋窝Ⅰ—Ⅲ站及前哨淋巴结剂量覆盖评估

目的 评估早期乳腺癌保乳术后全乳逆向IMRT对腋窝Ⅰ、Ⅱ、Ⅲ站及前哨淋巴结区域的剂量覆盖情况。方法 回顾分析2008—2012年间在复旦大学附属肿瘤医院接受保乳手术及前哨淋巴结活检术的40例乳腺癌患者临床资料。术后全乳逆向IMRT处方剂量为50 Gy分25次。按照RTOG标准及术中放置钛夹的位置勾画腋窝Ⅰ、Ⅱ、Ⅲ站及前哨淋巴结区域,并分析相应区域受量。结果 腋窝Ⅰ、Ⅱ、Ⅲ站淋巴结的平均剂量分别为(33.0±7.5)、(17.9±11.3)、(7.3±6.6) Gy,V₉₅分别为(29.9±17.7)%、(9.0±14.5)%、(0.1±0.3)%。所有前哨淋巴结均位于第Ⅰ站腋窝淋巴结区域,前哨淋巴结的平均剂量为(43.0±10.0) Gy,58%(19/33)的平均剂量>45 Gy。结论 采用逆向IMRT照射乳腺时,腋窝Ⅰ、Ⅱ、Ⅲ站淋巴结受量有限,对前哨淋巴结微转移且未清扫腋窝者应充分考虑这一因素。     

Mapping of the functional anatomy of lymphatic drainage to the axilla in early breast cancer: A cohort study of 933 cases

IntroductionThe aims of this study were to investigate the correlation between lymphatic drainage and the sentinel lymph node (SLN) status of the subregions in the context of the clinic-pathological parameters of the tumour and the coverage of the axillary volumes by standard and high tangential fields (STgF and HTgF) for whole breast radiotherapy and axillary reverse mapping (ARM).Patients and methods933 women with early breast cancer and clinically negative axillary status underwent breast surgery and SLN biopsy followed by axillary lymph node dissection in SLN-positive cases. The subregional localisation of the SLN(s) was registered and statistically analysed with the clinic-pathological characteristics of the breast tumour. In node-positive patients treated with breast-conserving therapy in whom the SLNs were found in the anterior or posterior axillary subregions, the axillary volumes were contoured using the Radiation Therapy Oncology Group contouring atlas (n = 61).ResultsIn 91.1% (n = 797) of the cases, the SLN appeared in the anterior, posterior or central subregions.Using HTgF, Level I or II were completely covered in 65.6% (40/61) and 6.6% (4/61) of the cases, respectively. With STgF, the complete coverage was 0% for both levels.6.8% (n = 63) of all cases had one positive lymph node in the expected ARM lymph node regions.DiscussionA SLN is more than likely to be present in the anterior, posterior and central axillary subregions. Tangential fields allow only limited coverage of the axillary volumes. Preserving the lateral subregion during ARM may increase the possibility of understaging.     

Dose coverage of axillary level I-III areas during whole breast irradiation with simplified intensity modulated radiation therapy in early stage breast cancer patients

Purpose

This study was designed to evaluate the dose coverage of axillary areas during whole breast irradiation with simplified intensity modulated radiation therapy (s-IMRT) and field-in-field IMRT (for-IMRT) in early stage breast cancer patients.

Methods

Sixty-one consecutive patients with breast-conserving surgery and sentinel lymph node biopsy were collected. Two plans were created for each patient: the s-IMRT and for-IMRT plan. Dosimetric parameters of axillary areas were compared.

Results

The average of mean doses delivered to the axillary level I areas in s-IMRT and for-IMRT plan were 27.7Gy and 29.1Gy (p = 0.011), respectively. The average of V47.5Gy, V45Gy and V40Gy (percent volume receiving≥ 47.5Gy, 45Gy and 40Gy) of the axillary level I in s-IMRT plan was significantly lower than that in for-IMRT plan (p < 0.001). For for-IMRT plans, patients with upper tangential border to humeral head ≤2cm, breast separation >19.3cm and body width >31.9cm had significantly higher mean dose in axillary level I area (p = 0.002, 0.007, 0.001, respectively).

Conclusion

Compared with for-IMRT plan, the s-IMRT plan delivered lower dose to axillary level I area. For centers using s-IMRT technique, caution should be exercised when selecting to omit axillary lymph node dissection for patients with breast conserving surgery and limited positive SLNs.     

Evaluation of a Novel Field-placement Algorithm for Locoregional Breast Cancer Radiotherapy Including the Internal Mammary Chain

Aims

Irradiation of the internal mammary chain (IMC) is increasing following recently published data, but the need for formal delineation of lymph node volumes is slowing implementation in some healthcare settings. A field-placement algorithm for irradiating locoregional lymph nodes including the IMC could reduce the resource impact of introducing irradiation of the IMC. This study describes the development and evaluation of such an algorithm.

Patterns of local-regional recurrence following parotid-sparing conformal and segmental intensity-modulated radiotherapy for head and neck cancer

Purpose: To analyze the patterns of local-regional recurrence in patients with head and neck cancer treated with parotid-sparing conformal and segmental intensity-modulated radiotherapy (IMRT).

Methods and Materials: Fifty-eight patients with head and neck cancer were treated with bilateral neck radiation (RT) using conformal or segmental IMRT techniques, while sparing a substantial portion of one parotid gland. The targets for CT-based RT planning included the gross tumor volume (GTV) (primary tumor and lymph node metastases) and the clinical target volume (CTV) (postoperative tumor bed, expansions of the GTVs and lymph node groups at risk of subclinical disease). Lymph node targets at risk of subclinical disease included the bilateral jugulodigastric and lower jugular lymph nodes, bilateral retropharyngeal lymph nodes at risk, and high jugular nodes at the base of skull in the side of the neck at highest risk (containing clinical neck metastases and/or ipsilateral to the primary tumor). The CTVs were expanded by 5 mm to yield planning target volumes (PTVs). Planning goals included coverage of all PTVs (with a minimum of 95% of the prescribed dose) and sparing of a substantial portion of the parotid gland in the side of the neck at less risk. The median RT doses to the gross tumor, the operative bed, and the subclinical disease PTVs were 70.4 Gy, 61.2 Gy, and 50.4 Gy respectively. All recurrences were defined on CT scans obtained at the time of recurrence, transferred to the pretreatment CT dataset used for RT planning, and analyzed using dose–volume histograms. The recurrences were classified as 1) “in-field,” in which 95% or more of the recurrence volume (V_recur) was within the 95% isodose; 2) “marginal,” in which 20% to 95% of V_recur was within the 95% isodose; or 3) “outside,” in which less than 20% of V_recur was within the 95% isodose.

Results: With a median follow-up of 27 months (range 6 to 60 months), 10 regional recurrences, 5 local recurrences (including one noninvasive recurrence) and 1 stomal recurrence were seen in 12 patients, for a 2-year actuarial local-regional control rate of 79% (95% confidence interval 68–90%). Ten patients (80%) relapsed in-field (in areas of previous gross tumor in nine patients), and two patients developed marginal recurrences in the side of the neck at highest risk (one in the high retropharyngeal nodes/base of skull and one in the submandibular nodes). Four regional recurrences extended superior to the jugulodigastric node, in the high jugular and retropharyngeal nodes near the base of skull of the side of the neck at highest risk. Three of these were in-field, in areas that had received the dose intended for subclinical disease. No recurrences were seen in the nodes superior to the jugulodigastric nodes in the side of the neck at less risk, where RT was partially spared.

Conclusions: The majority of local-regional recurrences after conformal and segmental IMRT were “in-field,” in areas judged to be at high risk at the time of RT planning, including the GTV, the operative bed, and the first echelon nodes. These findings motivate studies of dose escalation to the highest risk regions.     

Matching supraclavicular fields to the extent of axillary surgery in women prescribed radiotherapy for early stage carcinoma of the breast

AimsTo determine (1) if the lower border of a standard anterior radiotherapy field to the supraclavicular fossa matches the upper limit of level II/III axillary dissection; and (2) whether standard lung blocks in patients prescribed axillary radiotherapy shield target axillary tissue in women with breast cancer.Materials and methodsBetween 1999 and 2001, 30 women with breast cancer undergoing level II/III axillary dissection had titanium clips placed to define the upper and medial limits of surgery. At radiotherapy planning, a supraclavicular fossa field similar to that described in the UK START trial protocol was simulated, with head twist applied to position the inferior field border (50% isodose) 1 cm below and parallel to the lower border of the clavicle. The field position was recorded on X-ray film. The location of the most superior axillary clip was measured in relation to this inferior field border on the X-ray film. The location of the most medial clip was measured in relation to the lung/chest wall interface.ResultsThe median distance between the most superior clip and the inferior border of the supraclavicular field was 3.6 cm (0.8–6.9 cm), representing significant underlap in all cases. In addition, five out of 30 (17%) patients had surgical clips over 2.0 cm medial to the lung/chest wall interface, suggesting that medial lymph nodes in an undissected axilla would be shielded by standard lung blocks in patients prescribed axillary radiotherapy.ConclusionCurrent standard radiation fields to the supraclavicular fossa, as applied in this study, leave apical axillary lymph nodes untreated in a high proportion of patients. Standard lung shielding, as applied in this study to patients simulated for axillary radiotherapy, protect medial axillary lymph nodes in a few patients. A change in practice is recommended.     

The impact of central lung distance,maximal heart distance,and radiation technique on the volumetric dose of the lung and heart for intact breast radiation

PURPOSE: To investigate the impact of radiographic parameter and radiation technique on the volumetric dose of lung and heart for intact breast radiation. METHODS AND MATERIALS: Forty patients with both two-dimensional (2D) and computed tomographic (CT) simulations were enrolled in the study. Central lung distance (CLD), maximal heart distance (MHD), and maximal heart length (MHL) were measured under virtual simulation. Four plans were compared for each patient. Plan A used a traditional 2D tangential setup. Plan B used clinical target volume (CTV) based three-dimensional (3D) planning. Both plans C and D used a combination of a medial breast field with shallow tangents. Plan D is a further modification of plan C. RESULTS: Under the traditional tangential setup, the mean ipsilateral lung dose and volume at 20, 30, and 40 Gy correlated linearly with CLD (R = 0.85 approximately 0.91). The mean ipsilateral lung dose (Gy) approximated 4 times the CLD value (cm), whereas the percentage volume (%) of ipsilateral lung at 20, 30, and 40 Gy was about 10 times the CLD (cm). The mean heart dose and percentage volume at 20, 30, and 40 Gy correlated with MHD (R = 0.76 approximately 0.80) and MHL (R = 0.65 approximately 0.75). The mean heart dose (Gy) approximated 3 times the MHD value (cm), and the percentage volume (%) of the heart at 10, 20, 30, and 40 Gy was about 6 times MHD (cm). Radiation technique impacted lung and heart dose. The 3D tangential plan (plan B) failed to reduce the volumetric dose of lung and heart from that of the 2D plan (plan A). The medial breast techniques (plans C and D) significantly decreased the volume of lung and heart receiving high doses (30 and 40 Gy). Plan D further decreased the 20 Gy volumes. By use of the medial breast technique, the lung and heart dose were not impacted by original CLD and MHD/MHL. Therefore, the improvement from the tangential technique was more remarkable for patients with CLD >or= 3.0 cm (p < 0.001). CONCLUSIONS: The CLD and MHD impact the volumetric dose of lung and heart. The application of 3D planning for tangential breast irradiation does not decrease heart and lung dose. Adding a medial breast port significantly decreases percentage volume (PV) of lung and heart receiving high doses, especially when the CLD is excessive.