N. Fournier-Bidoz

How to Boost the Breast Tumor Bed? A Multidisciplinary Approach in Eight Steps

PURPOSE To describe a new procedure for breast radiotherapy that will improve tumor bed localization and radiotherapy treatment using a multidisciplinary approach. PATIENTS AND METHODS This pilot study was conducted by departments of radiation oncology, surgery, and radiology. A new procedure has been implemented, summarized as eight steps: from pre-surgery contrast CT to surgery, tumor bed planning target volume (PTV) determination, and finally breast and tumor bed irradiation. RESULTS Twenty patients presenting with T1N0M0 tumors were enrolled in the study. All patients underwent lumpectomy with the placement of surgical clips in the tumor bed region. During surgery, 1 to 5 clips were placed in the lumpectomy cavity before the plastic procedure. All patients underwent pre- and postoperative CT scans in the treatment position. The two sets of images were registered with a match-point registration. All volumes were contoured and the results evaluated. The PTV included the clips region, the gross tumor volume, and the surgical scar, with an overall margin of 5-10 mm in all directions, corresponding to localization and setup uncertainties. For each patient the boost PTV was discussed and compared with our standard forward-planned PTV. CONCLUSIONS We demonstrate the feasibility of a tumor bed localization and treatment procedure that seems adaptable to routine practice. Our study shows the advantages of a multidisciplinary approach for tumor bed localization and treatment. The use of more than 1 clip associated with pre- to postoperative CT image registration allows better definition of the PTV boost volume.

Simultaneous integrated boost in breast conserving treatment of breast cancer: A dosimetric comparison of helical tomotherapy and three-dimensional conformal radiotherapy

BACKGROUND AND PURPOSE To evaluate the dosimetry of helical tomotherapy (HT) and three-dimensional conformal radiotherapy (3D-CRT) in breast cancer patients undergoing whole breast radiation with simultaneous integrated boost (SIB) of the tumor bed. MATERIAL AND METHODS Thirteen patients with breast cancer treated by lumpectomy and requiring whole breast radiotherapy with tumor bed boost were planned using both HT and 3D-CRT using the field-in-field technique. The whole breast and tumor bed were prescribed 50.68 Gy and 64.4 Gy, respectively, in 28 fractions. Dosimetries for both techniques were compared. RESULTS Coverage of the whole breast was adequate with both techniques (V(95%)=96.22% vs. 96.25%, with HT and 3D-CRT, respectively; p=0.64). Adequate tumor bed coverage was also achieved, although it was significantly lower with HT (V(95%)=97.18% vs. 99.72%; p<0.001). Overdose of the breast volume outside the tumor bed was significantly lower with HT (V(54.23 Gy)=12.47% vs. 30.83%; p<0.001). Ipsilateral lung V(20 Gy) (6.34% vs. 10.17%; p<0.001), V(5 Gy) (16.54% vs. 18.53%; p<0.05) and mean dose (4.05 Gy vs. 6.36 Gy; p<0.001) were significantly lower with HT. In patients with left-sided tumors, heart V(30 Gy) (0.03% vs. 1.14%; p<0.05) and mean dose (1.35 Gy vs. 2.22 Gy; p<0.01) were significantly lower with HT, but not V(5 Gy). Contralateral breast V(5 Gy) (0.27% vs. 0.00%; p<0.01) and maximum dose were significantly increased with HT. CONCLUSIONS In breast cancer treated with SIB, both HT and 3D-CRT provided adequate target volume coverage and low heart doses. Tumor bed coverage was slightly lower with HT, but HT avoided unnecessary breast overdosage while improving ipsilateral lung dosimetry.

Anatomical, clinical and radiological delineation of target volumes in breast cancer radiotherapy planning: individual variability, questions and answers

The purpose of the study was to evaluate the individual variability of anatomical and radiological delineation for breast cancer radiotherapy (RT) in preparation for new techniques and to propose practical solutions to improve delineation in everyday practice. In the first phase, a patient with stage T3N3M0 breast cancer and complete response after neoadjuvant chemotherapy was assessed by CT scan in the treatment position before RT. 11 radiation oncologists (5 breast cancer specialists and 6 residents) independently delineated the breast and lymph node (LN) regions before definition of target volumes. Organs at risk (heart, lung, thyroid and brachial plexus) were also delineated. All regions (breast, axilla, supraclavicular LN, infraclavicular LN and internal mammary chain) were delineated and compared in terms of volume. Comparative analysis was performed with Aquilab software. Differences in the clinical and radiological assessment were observed between the various radiation oncologists. Simplified rules of delineation were developed in the department. Using these rules, the second patients CT was delineated by the same physicians and better results were observed. Simplified rules of delineation were developed. In conclusion, major differences in anatomical and radiological delineation for breast cancer RT were observed among the physicians. This study led to the development of written delineation protocols. The study is ongoing with evaluation of the dosimetric impact and definition of different target volumes.

IMPROVING THE DEFINITION OF TUMOR BED BOOST WITH THE USE OF SURGICAL CLIPS AND IMAGE REGISTRATION IN BREAST CANCER PATIENTS

PURPOSE To evaluate the accuracy of a boost technique. METHODS AND MATERIALS Twenty-two patients underwent tumorectomy with placement of two or more clips in the surgical cavity before breast remodeling. Preoperative and postoperative computed tomography scans, with match-point registration, were performed on all patients. The relationship between the location of the gross tumor volume (GTV), defined on the preoperative scan, and clip clinical target volume (CTV) (clips with a 5-mm margin on the postoperative scan) was then studied, by use of commercial volume analysis software. RESULTS Of the patients, 4 had two clips, 2 had three clips, 8 had four clips, and 8 had five clips. The median GTV was 1.06 mL (range, 0.2-5.3 mL); clip CTV ranged from 2.4 to 21.5 mL. Volumetric analysis showed that in 7 cases (32%), there was no intersection between the GTV and the clip CTV, with the following distribution: 4 patients with two clips, 1 patient with three clips, 1 patient with four clips, and 1 patient with five clips. The common contoured volume was defined as the percent ratio between the intersection of the GTV and clip CTV and the GTV. It was found to be significantly increased if three or more clips were used vs. only two clips (common contoured volume, 35.45% vs. 0.73%; p = 0.028). Finally, the GTV and clip CTV volume relationship can be presented as follows: 12.5% to 33% overlap in 8 patients (36.4%), 50% to 75% in 5 patients (22.7%), and greater than 90% in 2 patients (9%). CONCLUSIONS The use of three or more clips during tumorectomy increases the accuracy of tumor bed delineation.

Whole breast radiotherapy in the lateral decubitus position: A dosimetric and clinical solution to decrease the doses to the organs at risk (OAR)

PURPOSE To evaluate whole breast 3D-conformal radiotherapy (RT) delivered in the lateral decubitus position (isocentric lateral decubitus [ILD]) and to report the acute toxicity of a series of consecutive patients treated with ILD. MATERIALS AND METHODS From January to December 2010, 56 consecutive patients with large breasts and early-stage breast cancer treated by breast conserving surgery underwent 3D-conformal whole breast RT in the lateral decubitus position. A dose of 50 Gy in 25 fractions via two opposed isocentric beams was prescribed to whole breast, with or without a 16 Gy photon tumor bed boost. Dosimetry of all patients was reviewed, and the acute toxicity of treatment, evaluated weekly using the NCI CTC v3.0 scale, was analyzed. RESULTS Median age was 57 years (range: 33-71). 85% of patients had a breast circumference of at least 95 cm and 80% had at least a C cup size. Average breast volume was 991 cm(3) (range: 225-2791 cm(3)). Median dose to the breast was 50 Gy, while median dose to the tumor bed was 16 Gy. Grade 1, 2 and 3 dermatitis developed in 37.5%, 58.9% and 1.8% of patients, respectively. From a dosimetric point of view, doses to the ipsilateral lung were extremely low: average V(1Gy), V(2Gy) and V(5Gy) were 26.6%, 9.3% and 0.7%, respectively. Average mean lung dose was 0.96 Gy. For the 26 patients with left-sided tumors, heart doses were also extremely low: average V(1Gy), V(2Gy) and V(5Gy) were 58.8%, 14.2% and 0.7%, respectively. Average mean heart dose was 1.35 Gy. CONCLUSION Whole breast radiotherapy in the lateral decubitus position for patients with large breasts and early-stage breast cancer provides an excellent dosimetric profile, with low doses to the heart and ipsilateral lung. It is also very well tolerated, with a good acute toxicity profile.

Visualisation of the left anterior descending coronary artery on CT images used for breast radiotherapy planning

OBJECTIVE To assess the visualisation of the left anterior descending (LAD) coronary artery on CT images used for breast radiation treatment planning. METHODS Delineation of the LAD artery was achieved for 25 breast patients by 1 radiologist and 1 radiation oncologist independently on two sets of images for each patient: one pre-operative CT scan using intravenous (IV) contrast media to determine the primary gross tumour volume (GTV) and one post-operative CT scan used for treatment planning. A Students paired t-test was used to compare the number of CT slices in which the LAD was visible for each patient in the two series. Interpolations and extrapolations of the LAD volume were performed for the left-sided cases using a published heart atlas in order to report doses to the LAD structure. RESULTS There was a non-significant difference between the results with and without IV contrast media (p=0.34 for the radiologist; p=0.90 for the radiation oncologist). The visible LAD artery corresponded to a 30% portion (range 12-47%) of the interpolated structure. The maximum dose to the left artery varied widely, from 2.7 to 41.7 Gy, in the group of patients with left breast tumours. The largest values (>25 Gy) corresponded to those patients in whom the LAD artery distal extremity lay inside the breast fields. CONCLUSIONS With the current planning CT protocol, only one-third of the LAD artery could be objectively visualised. Contrast-enhanced imaging used for GTV delineation before the breast surgery did not improve the visualisation of the artery. ADVANCES IN KNOWLEDGE This study has revealed the lack of consistency that may be encountered when contouring heart vessels, thereby questioning the reliability of dose reporting.

Potential benefits of using cardiac gated images to reduce the dose to the left anterior descending coronary during radiotherapy of left breast and internal mammary nodes.

PURPOSE To assess the benefits of using cardiac gated images for treatment planning of breast and internal mammary nodes. PATIENTS AND METHODS Inspiration breath hold computed tomography (CT) series acquired at prospectively gated diastolic phase were used for planning. Three different techniques were compared. Technique A used tangents and an internal mammary nodes field covering the three first inter-rib spaces; technique B used an extended internal mammary nodes including part of the medial breast in junction with tangential fields; the 3(rd) technique used helical tomotherapy. For each technique, two treatment plans were performed: one plan (plan-01) where mean dose and V(25) to the heart were considered for plan evaluation and a second plan (plan-02) where the irradiation of the left anterior descending artery was minimized. RESULTS V(25) to the heart was found to be less than 5% for all six plans. Mean doses to the heart were within 4.8 to 7.2 Gy. By attempting to lower the dose to the left anterior descending artery, heart D(mean) was decreased by 20-30% for the two techniques A and B while being unchanged for tomotherapy. Regarding target coverage, there was no marked difference between plans where only heart dose was considered (plans-01) and plans where the left anterior descending artery dose was minimized (plans-02). When the left anterior descending artery dose was part of plan evaluation, D(mean) to the left anterior descending artery could be decreased by 24, 19 and 9% for techniques A, B and tomotherapy respectively. The three techniques exposed segments of the left coronary to different levels of dose. CONCLUSION This study showed that evaluation of the dose to the left anterior descending artery coronary may change the treatment strategy. Cardiac gated images without IV contrast permitted a good visualization of the coronaries in order to optimize the dose on these structures. In addition to heart V(25,) the dose to the coronaries should be included in prospective studies on radiotherapy related heart toxicity in association with all additional risk factors.

Implant breast reconstruction followed by radiotherapy: Can helical tomotherapy become a standard irradiation treatment?

To evaluate the benefits and limitations of helical tomotherapy (HT) for loco-regional irradiation of patients after a mastectomy and immediate implant-based reconstruction. Ten breast cancer patients with retropectoral implants were randomly selected for this comparative study. Planning target volumes (PTVs) 1 (the volume between the skin and the implant, plus margin) and 2 (supraclavicular, infraclavicular, and internal mammary nodes, plus margin) were 50 Gy in 25 fractions using a standard technique and HT. The extracted dosimetric data were compared using a 2-tailed Wilcoxon matched-pair signed-rank test. Doses for PTV1 and PTV2 were significantly higher with HT (V95 of 98.91 and 97.91%, respectively) compared with the standard technique (77.46 and 72.91%, respectively). Similarly, the indexes of homogeneity were significantly greater with HT (p = 0.002). HT reduced ipsilateral lung volume that received ≥20 Gy (16.7 vs. 35%), and bilateral lungs (p = 0.01) and neighboring organs received doses that remained well below tolerance levels. The heart volume, which received 25 Gy, was negligible with both techniques. HT can achieve full target coverage while decreasing high doses to the heart and ipsilateral lung. However, the low doses to normal tissue volumes need to be reduced in future studies.

Helical Tomotherapy for Inoperable Breast Cancer: A New Promising Tool

Background. We investigated the feasibility of helical tomotherapy (HT) for inoperable large breast tumors, after failing to achieve adequate treatment planning with conformal radiation techniques. Material and Methods. Five consecutive patients with locally advanced breast cancer (LABC) were treated by preoperative HT. All patients received up-front chemotherapy before HT. Irradiated volumes included breast and nodal areas (45–50 Gy) in 4 patients. One patient received a simultaneous integrated boost (55 Gy) to gross tumor volume (GTV) without lymph node irradiation. Acute toxicity was assessed with Common Toxicity Criteria for Adverse Events v.4. Patients were evaluated for surgery at the end of treatment. Results. Patients were staged IIB to IIIC (according to the AJCC staging system 2010). HT was associated in 4 patients with concomitant chemotherapy (5-fluorouracil and vinorelbine). Two patients were scored with grade 3 skin toxicity (had not completed HT) and one with grade 3 febrile neutropenia. One patient stopped HT with grade 2 skin toxicity. All patients were able to undergo mastectomy at a median interval of 43 days (31–52) from HT. Pathological partial response was seen in all patients. Conclusions. HT is feasible with acceptable toxicity profiles, potentially increased by chemotherapy. These preliminary results prompt us to consider a phase II study.

Résultats préliminaires d’une tomothérapie hélicoïdale adjuvante avec boost intégré dans le cadre d’un traitement conservateur d’un cancer du sein

PURPOSE To evaluate the dosimetry and acute toxicity of helical tomotherapy for locoregional irradiation of patients after breast-conserving surgery. PATIENTS AND METHODS Twenty breast cancer patients with breast-conserving surgery treated by helical tomotherapy have been studied. The median age was 49 (min: 25, max: 69). The whole breast, tumour bed and lymph nodes were prescribed 52.2 Gy, 63.8 Gy and 50.4 Gy, all in 29 fractions. The dose per fraction was 2.2 Gy to the boost, 1.8 Gy to the breast and 1.74 Gy to the lymph node volumes. The reproducibility was analysed by recording the daily shifts in x, y and z directions and roll rotation. All toxicities were described using the Common Terminology Criteria for Adverse Effects v3.0. RESULTS Twenty-two tumours were irradiated. Six-eight percent were located in the inner quadrant. In 90 % of patients supraclavicular and internal mammary nodes were treated. The coverage of planning target volumes (PTV) was as follows: PTV boost: V107 = 0.3 % ± 0.5 SD, V95 = 98.4 % ± 1.9 SD; PTV breast: -V107 = 7.8 % ± 17.3 SD, V95 = 96.8 % ± 2.2 SD; PTV LN: V107 = 2.5 % ± 4.2 SD, V95 = 92.7 % ± 13.2 SD. The mean V20 of the homolateral lung was 18.9 % ± 3.5 SD. For left side lesion, the mean V30 of the heart was 0.9 % ± 0.8 SD. The mean V5 was: V5 homolateral lung: 73.1 % ± 11.8 ET, controlateral lung: 38.9 % ± 21, heart (left side breast): 57.3 % ± 21, controlateral breast: 15.5 % ± 9.6. Median shifts were as follow: x-axis -0.04 mm (IC 95: -0.4 +0.38), y-axis -0.37 mm ± 5.51 (IC 95: -0.88 +0.14), z-axis 2.90 mm ± 5.42 (IC 95:+2.4+3.4) and roll rotation 0.22 ± 1.10 (IC 95: -0.1+0.32). The treatment tolerance was acceptable with 1 definitive interruption couple of fractions before the end and 3 temporal interruptions for skin toxicity. No grade 3 or 4 toxicity. Ninety-five percent of patients experienced skin toxicity: 45 % grade 2. There were 3 cases of oesophagitis. The median follow-up of presented series is 9.7 months and all of the patients are free of disease without any residual early or late toxicity. CONCLUSIONS Helical tomotherapy can achieve full target coverage while protected to the heart and ipsilateral lung. This treatment was well tolerated and reproducible. However, the low doses to normal tissue volumes need to be reduced in future studies.