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

Reproducibility and stability of voluntary deep inspiration breath hold and free breath in breast radiotherapy based on real-time 3-dimensional optical surface imaging system

BACKGROUND

The aim of this study was to evaluate the inter-fraction reproducibility and intra-fraction stability of breast radiotherapy using voluntary deep-inspiration breath hold (DIBH) and free breathing (FB) based on an optical surface imaging system (OSIS).

METHODS

Seventeen patients (510 breath-hold sessions) treated using a field-in-field (FiF) technique and twenty patients (600 breath-free sessions) treated with a volume-modulated arc therapy (VMAT) technique were included in this retrospective study. All the patients were positioned with the guidance of CBCT and OSIS, and also monitored with OSIS throughout the whole treatment session. Eight setup variations in three directions were extracted from the treatment reports of OSIS for all sessions and were subsequently manually introduced to treatment plans, resulting in a total of 296 perturbed plans. All perturbed plans were recalculated, and the dose volume histograms (DVH) for the target and organs at risk (OAR) were analyzed.

RESULTS

The OSIS and CBCT for both DIBH and FB treatments showed a good agreement of less than 0.30 cm in each direction. The intra-fraction respiratory motion data during DIBH were -0.06 ± 0.07 cm, 0.12 ± 0.15 cm, and 0.12 ± 0.12 cm in the lateral, longitudinal, and vertical directions, respectively; for FB, the respiratory motion data were -0.02 ± 0.12 cm, 0.08 ± 0.18 cm, and 0.14 ± 0.20 cm, respectively. For the target, DIBH plans were more sensitive to setup errors; the mean deviations in D95 for CTV were 39.78 Gy-40.17 Gy for DIBH and 38.46 Gy-40.52 Gy for FB, respectively. For the OARs, the mean deviations of V10, V20, and Dmean to the heart; V5, V20, and Dmean to the ipsilateral lung; and Dmean to the breast were lower for the FB plan compared with the DIBH plan.

CONCLUSION

Based on OSIS, our results indicate that both DIBH and FB can provide good reproducibility in the inter-fractions and stability in the intra-fractions. When the patient respiratory motion is large, the FB technology has greater possibility for the undercoverage of the target volume, while DIBH technology is more likely to result in increases in dose to OARs (the lung, heart, and contralateral breast).

Should the management of radiation therapy for breast cancer be standardized? Results of a survey on current French practices in breast radiotherapy

Background

Breast cancer is the most frequent cancer in women in France. Its management has evolved considerably in recent years with a focus on reducing iatrogenic toxicity. The radiotherapy indications are validated in multidisciplinary consultation meetings; however, questions remain outstanding, particularly regarding hypofractionated radiotherapy, partial breast irradiation, and irradiation of the internal mammary chain and axillary lymph node area.

Materials and methods

An online survey was sent to 47 heads of radiotherapy departments in France. The survey consisted of 22 questions concerning indications for irradiation of the supraclavicular, internal mammary and axillary lymph node areas; irradiation techniques and modalities; prescribed doses; and fractionation.

Results

Twenty-four out of 47 centers responded (response rate of 51%). This survey demonstrated a wide variation in the prescribed dose regimen, monoisocentric radiotherapy, and indications of irradiation of the lymph node areas.

Conclusion

This survey provides insight into the current radiotherapy practice for breast cancer in France. It shows the need to standardize practices.

Unintended dose to the lower axilla in adjuvant radiotherapy for breast cancer: Differences between tangential beam and VMAT

BACKGROUND AND PURPOSE

To evaluate dosimetric differences in unintended dose to the lower axilla between 3D-standard (3DCRT), tangential beam forward intensity modulated radiotherapy (F-IMRT) and volumetric modulated arc therapy (VMAT). The objective is to evaluate whether results of clinical trials, such as the ACOSOG-Z011 trial, that evaluated omission of axillary clearance can be extrapolated towards more conformal techniques like VMAT.

MATERIALS AND METHODS

Twenty-five consecutive patients treated with whole breast radiotherapy alone (WBRT) using a F-IMRT technique were identified. Three additional plans were created for every patient: one plan using a single 270° arc (VMAT 1x270°), another using two small ≤90° opposing arcs (VMAT 2x < 90°) and thirdly a 3DCRT plan without F-IMRT. Axillary levels I-II were contoured after the treatment plans were made.

RESULTS

The volume of the axilla level I that was covered by the 50% isodose (V50%) was significantly higher for VMAT 2x < 90° (71.3 cm³, 84% of structure volume, p < 0.001) and VMAT 1x270° (68.8 cm³, 81%, p < 0.01) compared to 3DCRT (60.3 cm³, 71%) and F-IMRT (60.8 cm³, 72%). The V50% to the axilla level II, however, was low for all techniques: 12.3 cm³ (12%); 8.9 cm³ (9%); 4.3 cm³ (4%); 4.4 cm³ (4%) for VMAT 2x < 90°, VMAT 1x270°, 3DCRT, F-IMRT, respectively. For the higher doses (V90% and above), no clinically relevant differences were seen between the different modalities.

CONCLUSION

WBRT treatments with VMAT do not lead to a significant reduction of the unintended axillary dose in comparison with a tangential beam setup. Hence, concerning tumor control, VMAT can be applied to clinical situations similar to the Z0011 trial. The intermediate axillary dose is higher with VMAT, but the clinical consequence of this difference on toxicity is unknown.

Incidental axillary dose delivery to axillary lymph node levels I-III by different techniques of whole-breast irradiation: a systematic literature review

BACKGROUND AND OBJECTIVE

In breast cancer treatment, radiotherapy is an essential component for locoregional management. Axillary recurrence in patients with invasive breast carcinoma remains an issue. The question of whether breast irradiation may unintentionally include levels I, II, and III, and may decrease the risk of axillary recurrence, remains a topic of discussion.

PATIENTS AND METHODS

A literature search was performed in PubMed and the Cochrane Library to identify articles that have published data regarding dose-volume analysis of axillary levels in breast irradiation. The following MESH terms were used: "breast cancer/lymph nodes" AND "radiotherapy dosage."

RESULTS

Thirteen articles were identified. The irradiation technique, initial dose prescribed to the breast, delineated volumes, and dose received at axillary levels were heterogeneous. The average dose delivered to axilla levels I, II, and III with three-dimensional conformal radiotherapy using standard fields (ST) ranged between 22 and 43.5 Gy, 3 and 35.6 Gy, and 1.0 and 20.5 Gy, respectively. The average doses delivered to axilla levels I, II, and III with three-dimensional conformal radiotherapy using "high tangential" fields (HT) ranged between 38 and 49.7 Gy, 11 and 47.1 Gy, and 5 and 44.7 Gy, respectively. Finally, the average doses delivered to axilla levels I, II, and III using intensity-modulated radiation therapy (IMRT) were between 14.5 and 42.6 Gy, 3.4 and 35 Gy, and 1.2 and 25.5 Gy, respectively.

CONCLUSION

Our literature review suggests that the incidental dose delivered to the axilla during whole-breast irradiation is heterogenous and dependent on the irradiation technique used. However, whether this observation can be translated into a therapeutic effect is still a matter of debate.

Are we missing the post-operative cavity in whole breast radiotherapy?

BACKGROUND/PURPOSE

Whole breast radiotherapy (RT) following breast-conserving surgery is a standard treatment option in early-stage breast cancer patients. The whole breast RT technique targets the entire breast, traditionally identified based on breast palpation and the lumpectomy scar. The aim of this study is to evaluate dosimetry of the tumour bed (cavity) and location of recurrence in women treated with breast radiotherapy without explicit cavity delineation.

MATERIALS/METHODS

50 consecutive women previously treated with whole breast RT were retrospectively contoured to define the post-operative cavity with a 1.0 cm expansion for planning target volume (cPTV). The cavity and cPTV dosimetric coverage [volume receiving 92%(V92%) and 95%(V95%) prescription] were calculated. Cavity and cPTV location were classified as inside, at edge or outside of previous treatment fields and recurrence rates were collected.

RESULTS

Forty-five (90%) women had cavities located inside the previous treatment fields (CAVin) and 5 women (10%) had cavities located outside(4) or at edge(1) of previous fields (CAVout/edge). CAVout/edge were located in extreme aspects of the breast: lateral(3); medial(1); or superior(1). Mean cavity_V92% was 91.6% vs 98.5% for CAVout/edge vs CAVin (p = 0.042). Mean cPTV_V92% was 78.7% vs 97.2% for cPTVout/edge vs cPTVin (p<0.001). At 5-year follow-up, 20% (1/5) of the CAVout/edge had 1 in-breast recurrence near the cavity (at previous field edge). Within the CAVin cohort, 11 patients were lost to follow-up and 6% (2/34) patients had in-breast recurrence.

CONCLUSIONS

In patients treated with whole breast RT without cavity delineation, 10% did not have ideal dosimetric coverage of the cavity. Cavity delineation in treatment planning provides optimal tumour bed coverage for patients undergoing whole breast RT, and is of particular importance for the coverage of cavities located in the extreme margins of the breast.

[Diffusion prophylactic axillary irradiation in breast cancer - Literature review]

PURPOSE

In breast cancer, radiotherapy is an essential component of the treatment. However, indications of irradiation of the internal mammary chain and axillary area are debatables. Axillary recurrence in patients with invasive breast carcinoma remains an issue. Currently, the substitution of axillary lymph node dissection by sentinel node biopsy leads to revisit the role of axillary irradiation. Breast irradiation including level I, II and III might decrease the risk of axillary recurrence.

MATERIAL AND METHODS

A literature search was performed in PubMed and the Cochrane library to identify articles publishing data regarding dose-volume analysis of axillary levels in breast irradiation aiming to determine the potential therapeutic implications.

RESULTS

Eleven articles were retained. A total of 375 treatment plans were analyzed. The results concerning the irradiation technique, initial dose prescribed to breast, delineated volumes and dose received at axillary levels were heterogeneous. The average dose delivered to axilla levels I-III with 3D-conformal radiotherapy using standard fields were between 24Gy and 43.5Gy, 3Gy and 32.5Gy and between 1.0Gy and 20.5Gy respectively. The average doses delivered to axilla levels I-III with 3D-conformal radiotherapy using high tangential fields were between 38Gy and 49.7Gy, 11Gy and 47.1Gy and 5Gy 38.7Gy, 32.1Gy and 5Gy (result available for only one study) respectively. Finally, the average doses delivered to axilla levels I-III with intensity modulated radiation therapy were between 14.5Gy and 42.6Gy, 3.4Gy and 35Gy and between 1.2Gy and 25.5Gy respectively.

CONCLUSIONS

Incidental axillary dose seems insufficient to be therapeutic regardless of the irradiation technique. There are meaningful differences between intensity modulated radiation therapy and 3D-conformal radiotherapy.

Impact of Positioning Errors on the Dosimetry of Breath-Hold-Based Volumetric Arc Modulated and Tangential Field-in-Field Left-Sided Breast Treatments

Heart diseases and cardiovascular events are well-known side effects in left-sided breast irradiation. Deep inspiration breath hold (BH) combined with fast delivery techniques such as volumetric modulated arc therapy (VMAT) or tangential field-in-field (TFiF) can serve as a valuable solution to reduce the dose to the heart. This study aims to compare the impact of positioning errors in VMAT and TFiF plans for BH left-sided breast treatments. Fifteen left-sided breast patients treated in BH with TFiF technique were included in this retrospective study. For each patient, a second plan with VMAT technique was optimized. Eighteen setup variations were introduced in each of these VMAT and TFiF reference plans, shifting the isocenter along six different directions by 3, 5, and 10 mm. A total of 540 perturbed plans, 270 for each technique, were recalculated and analyzed. The dose distributions on the target and organs at risk obtained in the different perturbed scenarios were compared with the reference scenarios, using as dosimetric endpoints the dose-volume histograms (DVH). The results were compared using the Wilcoxon test. Comparable plan quality was obtained for the reference VMAT and TFiF plans, except for low doses to organs at risk for which higher values (p < 0.05) were obtained for VMAT plans. For TFiF plans, perturbations of the isocenter position of 3, 5, or 10 mm produced mean deviations of the target DVH dosimetric parameters up to -0.5, -1.0, and -5.2%, respectively; VMAT plans were more sensitive to positioning errors resulting in mean deviations up to -0.5, -4.9, and -13.9%, respectively, for the same magnitude of the above mentioned perturbations. For organs at risk, only perturbations along the left, posterior, and inferior directions resulted in dose increase with a maximum deviation of +2% in the DVH dosimetric parameters. A notable exception were low doses to the left lung and heart for 10 mm isocenter shifts for which the mean differences ranged between +2.7 and +4.1%. Objective information on how external stresses affect the dosimetry of the treatment is the first step towards personalized radiotherapy.

Impact of positioning errors in the dosimetry of VMAT left-sided post mastectomy irradiation

Background

Volumetric modulated arc therapy (VMAT) adopted in post-mastectomy radiation therapy (PMRT) has the capacity to achieve highly conformal dose distributions. The research aims to evaluate the impact of positioning errors in the dosimetry of VMAT left-sided PMRT.

Methods

A total of 18 perturbations where introduced in 11 VMAT treatment plans that shifted the isocenter from its reference position of 3, 5, 10 mm in six directions. The thoracic wall and supraclavicular clinical target volumes (CTVs), the heart and the left lung dose volume histograms (DVHs) of 198 perturbed plans were calculated. The absolute differences (∆) of the mean dose (Dm) and DVH endpoints Vx and Dy (percentage volume receiving x Gy, and dose covering y% of the volume, respectively) were used to compare the dosimetry of the reference vs perturbed plans.

Results

Isocenter shifts in the anterior and lateral directions lead to maximum disagreement between the CTVs dosimetry of perturbed vs reference plans. Isocenter shifts of 10 mm shown a decrease of D95, D98 and Dm of 12.8, 18.0, and 2.9% respectively, for the CTVs. For 5 mm isocenter shifts, these differences decreased to 3.2, 5.2, and 0.9%, respectively, and for 3 mm shifts to 1.0, 1.7, and 0.6%, respectively. For the organs at risk (OARs), only isocenter shifts in the right, posterior and inferior directions worsen the plan dosimetry, nevertheless not negligible lung ∆ V20 of + 2.6%, and heart ∆ V25 of + 1.6% persist for 3 mm shifts.

Conclusions

Inaccuracy in isocenter positioning for VMAT left-sided PMRT irradiation may impact the dosimetry of the CTVs and OARs to a different extent, depending on the directions and magnitude of the perturbation. The acquired information could be useful for planning strategies to guarantee the accuracy of the treatment delivered.

Evaluation of interfraction setup variations for postmastectomy radiation therapy using EPID-based in vivo dosimetry

Postmastectomy radiation therapy is technically difficult and can be considered one of the most complex techniques concerning patient setup reproducibility. Slight patient setup variations — particularly when high‐conformal treatment techniques are used — can adversely affect the accuracy of the delivered dose and the patient outcome. This research aims to investigate the inter‐fraction setup variations occurring in two different scenarios of clinical practice: at the reference and at the current patient setups, when an image‐guided system is used or not used, respectively. The results were used with the secondary aim of assessing the robustness of the patient setup procedure in use. Forty eight patients treated with volumetric modulated arc and intensity modulated therapies were included in this study. EPID‐based in vivo dosimetry (IVD) was performed at the reference setup concomitantly with the weekly cone beam computed tomography acquisition and during the daily current setup. Three indices were analyzed: the ratio R between the reconstructed and planned isocenter doses, γ% and the mean value of γ from a transit dosimetry based on a two‐dimensional γ‐analysis of the electronic portal images using 5% and 5 mm as dose difference and distance to agreement gamma criteria; they were considered in tolerance if R was within 5%, γ% > 90% and γmean < 0.4. One thousand and sixteen EPID‐based IVD were analyzed and 6.3% resulted out of the tolerance level. Setup errors represented the main cause of this off tolerance with an occurrence rate of 72.2%. The percentage of results out of tolerance obtained at the current setup was three times greater (9.5% vs 3.1%) than the one obtained at the reference setup, indicating weaknesses in the setup procedure. This study highlights an EPID‐based IVD system's utility in the radiotherapy routine as part of the patient’s treatment quality controls and to optimize (or confirm) the performed setup procedures’ accuracy.

Incidental dose distribution to locoregional lymph nodes of breast cancer patients undergoing adjuvant radiotherapy with tomotherapy - is it time to adjust current contouring guidelines to the radiation technique?

Purpose/objective(s)

Along with breast-conserving surgery (BCS), adjuvant radiotherapy (RT) of patients with early breast cancer plays a crucial role in the oncologic treatment concept. Conventionally, irradiation is carried out with the aid of tangentially arranged fields. However, more modern and more complex radiation techniques such as IMRT (intensity-modulated radio therapy) are used more frequently, as they improve dose conformity and homogeneity and, in some cases, achieve better protection of adjacent risk factors. The use of this technique has implications for the incidental- and thus unintended- irradiation of adjacent loco regional lymph drainage in axillary lymph node levels I-III and internal mammary lymph nodes (IMLNs). A comparison of a homogeneous “real-life” patient collective, treated with helical tomotherapy (TT), patients treated with 3D conformal RT conventional tangentially arranged fields (3DCRT) and deep inspiration breath hold (3DCRT-DIBH), was conducted.

Materials/methods

This study included 90 treatment plans after BCS, irradiated in our clinic from January 2012 to August 2016 with TT (n = 30) and 3D-CRT (n = 30), 3DCRT DIBH (n = 30). PTVs were contoured at different time points by different radiation oncologists (> 7). TT was performed with a total dose of 50.4 Gy and a single dose of 1.8 Gy with a simultaneous integrated boost (SIB) to the tumor cavity (TT group). Patients irradiated with 3DCRT/3DCRT DIBH received 50 Gy à 2 Gy and a sequential boost. Contouring of lymph drainage routes was performed retrospectively according to RTOG guidelines.

Results

Average doses (DMean) in axillary lymph node Level I/Level II/Level III were 31.6 Gy/8.43 Gy/2.38 Gy for TT, 24.0 Gy/11.2 Gy/3.97 Gy for 3DCRT and 24.7 Gy/13.3 Gy/5.59 Gy for 3DCRT-DIBH patients. Internal mammary lymph nodes (IMLNs) Dmean were 27.8 Gy (TT), 13.5 Gy (3DCRT), and 18.7 Gy (3DCRT-DIBH). Comparing TT to 3DCRT-DIBH dose varied significantly in all axillary lymph node levels and the IMLNs. Comparing TT to 3DCRT significant dose difference in Level I and IMLNs was observed.

Conclusion

Dose applied to locoregional lymph drainage pathways varies comparing tomotherapy plans to conventional tangentially arranged fields. Studies are warranted whether dose variations influence loco-regional spread and must have implications for target volume definition guidelines.

Ipsilateral axillary recurrence after breast conservative surgery: The protective effect of whole breast radiotherapy

BACKGROUND AND PURPOSE

Whole breast radiotherapy (WBRT) is one of the possible reasons for the low rate of axillary recurrence after breast-conserving surgery (BCS).

PATIENTS AND METHODS

We retrospectively collected data from 4,129 consecutive patients with breast cancer ⩽2cm and negative sentinel lymph node who underwent BCS between 1997 and 2007. We compared the risk of axillary lymph node recurrence between patients treated by WBRT (n=2939) and patients who received partial breast irradiation (PBI; n=1,190) performed by a single dose of electron intraoperative radiotherapy.

RESULTS

Median tumour diameter was 1.1cm in both WBRT and PBI. Women who received WBRT were significantly younger and expressed significantly more multifocality, extensive in situ component, negative oestrogen receptor status and HER2 over-expression than women who received PBI. After a median follow-up of 8.3years, 37 and 28 axillary recurrences were observed in the WBRT and PBI arm, respectively, corresponding to a 10-year cumulative incidence of 1.3% and 4.0% (P<0.001). Multivariate analysis resulted in a hazard ratio of 0.30 (95% CI 0.17-0.51) in favour of WBRT.

CONCLUSIONS

In this large series of women with T1 breast cancer and negative sentinel lymph node treated by BCS, WBRT lowered the risk of axillary recurrence by two thirds as compared to PBI.

Coverage of Axillary Lymph Nodes with Tangential Breast Irradiation in Korea: A Multi-Institutional Comparison Study

Introduction. To evaluate the dose distribution and coverage of axilla using only tangential field for whole breast radiotherapy (RT) at three institutions in Korea. Methods. We used computed tomography (CT) images of nine consecutive 1-2 sentinel lymph node-positive patients who underwent breast conserving surgery and whole breast RT without axillary lymph node (ALN) dissection for clinical T1-2N0 breast cancer. The CT data were transferred to three radiation oncologists in 3 institutions and each radiation oncologist created treatment plans for all nine patients; a total of 27 treatment plans were analyzed. Results. The mean doses delivered to levels I and II were 31.9 Gy (9.9–47.9 Gy) and 22.3 Gy (3.4–47.7 Gy). Ninety-five percent of levels I and II received a mean dose of 11.8 Gy (0.4–43.0 Gy) and 3.0 Gy (0.3–40.0 Gy). The percent volumes of levels I and II covered by 95% of the prescribed dose were only 29.0% (0.2–74.1%) and 11.5% (0.0–70.1%). The dose distribution and coverage of axilla were significantly different between three institutions (p = 0.001). Conclusion. There were discrepancies in ALN coverage between three institutions. A standardization of whole breast RT technique through further research with a nationwide scale is needed.

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.

Axillary coverage by whole breast irradiation in 1 to 2 positive sentinel lymph nodes in breast cancer patients

PURPOSE

To evaluate the dosimetric coverage of axillary levels I, II, and III obtained with standard whole breast irradiation in 1 to 2 positive sentinel lymph nodes (SLNs) patients not submitted to axillary lymph nodes dissection (ALND), and to compare the lymph nodes areas coverage obtained with 3D conformal radiation therapy, intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT).

METHODS

Patients with 1 to 2 positive SLNs undergoing breast-conserving therapy, without ALND, were included in the analysis. For each patient, 3 treatment plans were performed: a 3D conventional tangential plan, a static IMRT plan, and a volumetric IMRT, designed to encompass the entire breast parenchyma. The volumes of axillary levels I, II, and III receiving 90% and 95% (V90, V95) of the whole breast prescribed dose were evaluated. Dose-volume histograms were compared by means of the Friedman test.

RESULTS

Ten patients were enrolled. All defined breast volumes received &gt;95% of the prescribed dose with the 3 techniques. Median V95 for axillary level I was 26.4% (range 4.7%-61.3%) for 3D plans, 8.6% (range 0.64%-19.1%) for static IMRT plans, and 2.6% (range 0.4%-4.7%) for volumetric IMRT plans (p&lt;0.001). Median V95 for axillary level II was 5.4% (range 0%-14.6%), 1.9% (range 0%-15%), and 2.6% (range 0.4%-4.7%) for 3D, static IMRT, and volumetric IMRT, respectively (p&lt;0.001).

CONCLUSIONS

Results of our analysis showed that standard 3D tangential whole breast irradiation failed to deliver a therapeutic dose to axillary levels I and II. The coverage was even lower using static and volumetric IMRT techniques.

Evaluation of Sentinel Lymph Node Dose Distribution in 3D Conformal Radiotherapy Techniques in 67 pN0 Breast Cancer Patients

Introduction. The anatomic position of the sentinel lymph node is variable. The purpose of the following study was to assess the dose distribution delivered to the surgically marked sentinel lymph node site by 3D conformal radio therapy technique. Material and Method. We retrospectively analysed 70 radiotherapy (RT) treatment plans of consecutive primary breast cancer patients with a successful, disease-free, sentinel lymph node resection. Results. In our case series the SN clip volume received a mean dose of 40.7 Gy (min 28.8 Gy/max 47.6 Gy). Conclusion. By using surgical clip markers in combination with 3D CT images our data supports the pathway of tumouricidal doses in the SN bed. The target volume should be defined by surgical clip markers and 3D CT images to give accurate dose estimations.

Dosimetric prospective study comparing 2D and 3D planning for irradiation of supraclavicular and infraclavicular regions in breast cancer patients

PURPOSE

The purpose of this study is to compare 2D plan and 3D plan regarding coverage of the target (supraclavicular and infraclavicular regions) and dose reaching the risk organs (using mean DVH). Depending on the results of this study, modifications can be made to the 2D conventional planning of supraclavicular and infraclavicular regions in order to achieve better coverage of the target tissues.

MATERIALS AND METHODS

This is a dosimetric study carried out at the radiation oncology department in NCI-Cairo University in the period from January 2012 to October 2012, on 15 patients with breast cancer who are eligible for supraclavicular and infraclavicular irradiation. For All patients, a 2D and a 3D plan were done.

RESULTS

We found that the coverage of the supraclavicular and infraclavicular regions and the chest wall or breast together with levels I and II axilla (PTV) were significantly better with the 3D technique with less over dose than the 2D technique. That difference was highly significant and was most evident in MRM cases. Also we found that organs at risk received a dose in the 3D technique that was more than that received in the 2D technique, again that difference was highly significant and was also most evident in MRM cases but all doses were still within tolerance.

CONCLUSIONS

From the present study we concluded that the coverage of the supraclavicular and infraclavicular PTV is significantly worse with the 2D technique using a single oblique field at a fixed depth of 3 cm for all patients despite their different builts.

Breast radiotherapy (RT) using tangential fields (TgF): a prospective evaluation of the dose distribution in the sentinel lymph node (SLN) area as determined intraoperatively by clip placement

BACKGROUND

Randomized trials have established that patients with limited involvement of sentinel lymph node (SLN) do not require axillary lymph node dissection (ALND). The similar outcome in patients with ≤2 positive SLN with or without additional ALND is attributed, in part, to tangential fields (TgF) RT. We evaluated the dose distribution in the SLN biopsy area (SLNBa) as determined intraoperatively by clips placement for radiotherapy (RT) optimization.

METHODS

This prospective study included 25 patients who had breast conservation. Titanium clips were used intraoperatively to mark the SLNBa. All patients had 3D-conformal RT using standard (STgF) or high tangential fields (HTgF). Axillary levels, SLNBa, and organs at risk were contoured on a CT scan. Dose distribution and overlap between TgF and target volumes were analyzed.

RESULTS

The average doses delivered to axilla levels I-III and SLNBa were 25, 5, 2, and 33 Gy, respectively. The average dose delivered to SLNBa was higher using HTgF with better coverage of the axilla. Only 12 of 25 patients (48 %) had their SLNBa completely covered by the TgF. There was no impact of TgF size on ipsilateral lung dose. The mean heart dose delivered using STgF was lower than HTgF.

CONCLUSIONS

In the era of SLNB, axilla and SNLBa RT technique has to be standardized to deliver adequate dose. We recommend the use of HTgF or direct axillary RT techniques (such as in AMAROS trial) in patients with metastases in SLN without ALND completion, when only TgF are expected to cure potential residual disease in the axilla.

Radiation dose to the nodal regions during prone versus supine breast irradiation

Background

Prone positioning for breast radiotherapy is preferable when the aim is a reduction of the dose to the ipsilateral lung or the heart in certain left-sided cases.

Materials and methods

In 100 breast cancer cases awaiting postoperative whole-breast radiotherapy, conformal radiotherapy plans were prospectively generated in both prone and supine positions. The axillary nodal region (levels I–III) and internal mammary (IM) lymph-node region in the upper three intercostal spaces were retrospectively contoured. The mean doses to the nodal regions and the volume receiving 25 Gy (V_25Gy), V_45Gy, and V_47.5Gy were compared between the two treatment positions.

Results

In most cases, the doses to axillary levels I–III and the IM lymph nodes were inadequate, regardless of the treatment position. The nodal doses were significantly lower in the prone than in the supine position. The radiation doses to levels II–III and IM nodes were especially low. The V_45Gy and V_47.5Gy of the level I axillary lymph nodes were 54.6% and 40.2%, respectively, in the supine, and 3.0% and 1.7%, respectively, in the prone position. In the supine position, only 17 patients (17%) received a mean dose of 45 Gy to the axillary level I nodes.

Conclusion

The radiation dose to the axillary and IM lymph nodes during breast radiotherapy is therapeutically insufficient in most cases, and is significantly lower in the prone position than in the supine position.

Incidental radiation to axilla in early breast cancer treated with intensity modulated tangents and comparison with conventional and 3D conformal tangents

PURPOSE

To analyze incidental radiation doses to minimally dissected axilla with Intensity modulated radiotherapy (IMRT), 3D conformal radiotherapy (3DCRT) and standard tangents (ST).

METHODS & MATERIALS

We prospectively evaluated incidental radiation to axilla in fifty cases of early breast cancer treated with breast conservation surgery with sentinel node biopsy alone followed by whole breast irradiation with IMRT. Three plans were devised for each CT dataset, comprising ST, 3DCRT and IMRT tangents. Doses to axillary nodal levels I, II and III were evaluated for mean dose, V95, V90, V80 and V50. Comparisons were made using ANOVA.

RESULTS

The mean doses delivered to axilla by the three techniques (IMRT, 3DCRT, ST) were: 78% (range 67-90, SD ± 5.2%), 80% (63-95, ±7.5%) and 87% (73-98, ±4.8%) for level I (IMRT vs ST; p = 0.037); 70% (46-89, ±12.4%), 72% (34-93, ±15.5%) and 65% (29-87, ±11.8%) for level II; and 51% (28-76, ±11.1%), 53% (19-86, ±13.7%) and 41% (6-72, ±10.6%) for level III, respectively. V90 values (volume receiving 90% of dose) for the three techniques were 49% (43-53, ±2.7%), 57% (51-65, ±3.1%) and 73% (65-80, ±3.4%) for level I (IMRT vs. ST; p = 0.029); 35% (26-42, ±4.7%), 41% (33-50, ±4.2%) and 25% (17-36, ±4.5%) for level II (IMRT vs ST; p = 0.068); and 15% (9-22, ±3.4%), 16% (10-24, ±3.7%) and 8 (5-12, ±3.1%) for level III (IMRT vs ST; p = 0.039), respectively.

CONCLUSION

Axillary levels I and II (lower axilla) receive substantial amount of incidental radiation doses with all the three techniques; however, conformal techniques (IMRT, 3DCRT) deliver significantly lesser incidental radiation to lower axilla than ST technique.

The standard tangential fields used for breast irradiation do not allow optimal coverage and dose distribution in axillary levels I-II and the sentinel node area

BACKGROUND

Recent data from ACOSOG Z0011 and NSABP B32 trials suggested no need for axillary lymph node dissection (ALND) in patients with micrometastatic involvement of the sentinel lymph node (SLN). The low rate of axillary recurrence was attributed to the axilla coverage by the tangential fields (TgFs) irradiation and systemic therapy. This study aimed to evaluate dose distribution and coverage of the axilla levels I-II and the SLN area.

PATIENTS AND METHODS

One hundred and nine patients were analyzed according to three groups: group 1 (50 Gy; n = 18), group 2 (60 Gy; n = 34) and group 3 (66 Gy; n = 57). Patients were treated using the standard (STgF; n = 22) or high (HTgF; n = 87) TgF.

RESULTS

The median doses delivered to level I using HTgF versus STgF were 33 and 20 Gy (P = 0.0001). The mean dose delivered to the SLN area was only 28 Gy. Additionally, the SLN area was totally included in the HTgF in 1 out of 12 patients who had intraoperative clip placement in the SNL area.

CONCLUSIONS

TgFs provide a limited coverage of the axilla and the SNLB area. This information should be considered when only TgFs are planned to target the axilla in patients with a positive SLN without ALND. Standardization of locoregional radiotherapy in this situation is urgently needed.

Complication rates in patients with negative axillary nodes 10 years after local breast radiotherapy after either sentinel lymph node dissection or axillary clearance

BACKGROUND

We assess complication rates in node negative breast cancer patients treated with breast radiotherapy (RT) only after sentinel lymph node dissection (SLND) or axillary lymph node dissection (ALND).

MATERIALS AND METHODS

Between 1995 and 2001, 226 women with AJCC stage I-II breast cancer were treated with lumpectomy, either SLND or SLND+ALND, and had available toxicities in follow-up: 111/136 (82%) and 115/129 (89%) in SLND and ALND groups, respectively. RT targeted the breast to median dose of 48.2 Gy (range, 46.0 to 50.4 Gy) without axillary RT. Chi-square tests compared complication rates of 2 groups for axillary web syndrome (AWS), seroma, wound infection, decreased range of motion of the ipsilateral shoulder, paresthesia, and lymphedema.

RESULTS

Median follow-up was 9.9 years (range, 8.3-15.3 y). Median number of nodes assessed was 2 (range, 1-5) in SLND and 18 (range, 7-36) in ALND (P < 0.0001). Acute complications occurred during the first 2 years and were AWS, seroma, and wound infection. Incidences of seroma 5/111 (4.5%) in SLND and 16/115 (13.9%) in ALND (P < 0.02, respectively) and wound infection 3/111 (2.7%) in SLND and 10/115 (8.7%) in ALND (P < 0.05, respectively) differed significantly. AWS was not statistically different between the groups. At 10 years, the only chronic complications decreased were range of motion of the shoulder 46/111 (41.4%) in SLND and 92/115 (80.0%) in ALND (P < 0.0001), paresthesia 12/111 (10.8%) in SLND and 39/115 (33.9%) in ALND (P < 0.0001), and lymphedema assessed by patients 10/111 (10.0%) in SLND and 39/115 (33.9%) in ALND (P < 0.0001). Chronic lymphedema, assessed by clinicians, occurred in 6/111 (5.4%) in SLND and 21/115 (18.3%) in ALND cohorts, respectively (P < 0.0001).

CONCLUSIONS

Our mature findings support that in patients with negative axillary nodal status SLND and breast RT provide excellent long-term cure rates while avoiding morbidities associated with ALND or addition of axillary RT field.

Axillary lymph node dose with tangential whole breast radiation in the prone versus supine position: a dosimetric study

Background

Prone breast positioning reduces skin reaction and heart and lung dose, but may also reduce radiation dose to axillary lymph nodes (ALNs).

Methods

Women with early stage breast cancer treated with whole breast irradiation (WBI) in the prone position were identified. Patients treated in the supine position were matched for treating physician, laterality, and fractionation. Ipsilateral breast, tumor bed, and Level I, II, and III ALNs were contoured according to the RTOG breast atlas. Clips marking surgically removed sentinel lymph nodes (SLN)s were contoured. Treatment plans developed for each patient were retrospectively analyzed. V90_% and V95_% was calculated for each axillary level. When present, dose to axillary surgical clips was calculated.

Results

Treatment plans for 46 women (23 prone and 23 supine) were reviewed. The mean V90_% and V95_% of ALN Level I was significantly lower for patients treated in the prone position (21% and 14%, respectively) than in the supine position (50% and 37%, respectively) (p < 0.0001 and p < 0.0001, respectively). Generally, Level II & III ALNs received little dose in either position. Sentinel node biopsy clips were all contained within axillary Level I. The mean V95_% of SLN clips was 47% for patients treated in the supine position and 0% for patients treated in the prone position (p < 0.0001). Mean V90_% to SLN clips was 96% for women treated in the supine position but only 13% for women treated in the prone position.

Conclusions

Standard tangential breast irradiation in the prone position results in substantially reduced dose to the Level I axilla as compared with treatment in the supine position. For women in whom axillary coverage is indicated such as those with positive sentinel lymph node biopsy who do not undergo completion axillary dissection, treatment in the prone position may be inappropriate.

Dose to level I and II axillary lymph nodes and lung by tangential field radiation in patients undergoing postmastectomy radiation with tissue expander reconstruction

BACKGROUND

To define the dosimetric coverage of level I/II axillary volumes and the lung volume irradiated in postmastectomy radiotherapy (PMRT) following tissue expander placement.

METHODS AND MATERIALS

Twenty-three patients were identified who had undergone postmastectomy radiotherapy with tangent only fields. All patients had pre-radiation tissue expander placement and expansion. Thirteen patients had bilateral expander reconstruction. The level I/II axillary volumes were contoured using the RTOG contouring atlas. The patient-specific variables of expander volume, superior-to-inferior location of expander, distance between expanders, expander angle and axillary volume were analyzed to determine their relationship to the axillary volume and lung volume dose.

RESULTS

The mean coverage of the level I/II axillary volume by the 95% isodose line (V(D95%)) was 23.9% (range 0.3 - 65.4%). The mean Ipsilateral Lung V(D50%) was 8.8% (2.2-20.9). Ipsilateral and contralateral expander volume correlated to Axillary V(D95%) in patients with bilateral reconstruction (p = 0.01 and 0.006, respectively) but not those with ipsilateral only reconstruction (p = 0.60). Ipsilateral Lung V(D50%) correlated with angle of the expander from midline (p = 0.05).

CONCLUSIONS

In patients undergoing PMRT with tissue expanders, incidental doses delivered by tangents to the axilla, as defined by the RTOG contouring atlas, do not provide adequate coverage. The posterior-superior region of level I and II is the region most commonly underdosed. Axillary volume coverage increased with increasing expander volumes in patients with bilateral reconstruction. Lung dose increased with increasing expander angle from midline. This information should be considered both when placing expanders and when designing PMRT tangent only treatment plans by contouring and targeting the axilla volume when axillary treatment is indicated.

Optimization of dose distribution with multi-leaf collimator using field-in-field technique for parallel opposing tangential beams of breast cancers

3 Dimensional Conformal Radiotherapy (3D-CRT) planning software helps in displaying the 3D dose distribution at different levels in the planned target volume (PTV). Physical or dynamic wedges are commonly applied to obtain homogeneous dose distribution in the PTV. Despite all these planning efforts, there are about 10% increased dose hot spots encountered in final plans. To overcome the effect of formation of hot spots, a manual forward planning method has been used. In this method, two more beams with multi-leaf collimator (MLC) of different weights are added in addition to medial and lateral wedged tangent beams. Fifteen patient treatment plans were taken up to check and compare the validity of using additional MLC fields to achieve better homogeneity in dose distributions. The resultant dose distributions with and without presence of MLC were compared objectively. The dose volume histogram (DVH) of each plan for the PTV was evaluated. The 3D dose distributions and homogeneity index (HI) values were compared. The 3D dose maximum values were reduced by 4% to 7%, and hot spots assumed point size. Optimizations of 3D-CRT plans with MLC fields improved the homogeneity and conformability of dose distribution in the PTV. This paper outlines a method of obtaining optimal 3D dose distribution within the PTV in the 3D-CRT planning of breast cases.

Coverage of axillary lymph nodes with high tangential fields in breast radiotherapy

The aim of this study is to evaluate the coverage of axillary nodal volumes with high tangent fields (HTF) in breast radiotherapy and to determine the utility of customised blocking. The treatment plans of 30 consecutive patients with early breast cancer were evaluated. The prescription dose was 50 Gy to the whole breast. Axillary level I-II lymph node volumes were delineated and the cranial border of the tangential fields was set just below the humeral head to create HTF. Dose-volume histograms (DVH) were used to calculate the doses received by axillary nodal volumes. In a second planning set, HTF were modified with multileaf collimators (MLC-HTF) to obtain an adequate dose coverage of axillary nodes. The mean doses of the axillary nodes, the ipsilateral lung and heart were compared between the two plans (HTF vs MLC-HTF) using a paired sample t-test. The doses received by 95% of the breast volumes were not significantly different for the two plans. The doses received by 95% of the level I and II axillary volumes were 16.79 Gy and 11.59 Gy, respectively, for HTF, increasing to 47.2 Gy and 45.03 Gy, respectively, for MLC-HTF. Mean lung doses and per cent volume of the ipsilateral lung receiving 20 Gy (V20) were also increased from 6.47 Gy and 10.47%, respectively, for HTF, to 9.56 Gy and 16.77%, respectively, for MLC-HTF. Our results suggest that HTF do not adequately cover the level I and II axillary lymph node regions. Modification of HTF with MLC is necessary to obtain an adequate coverage of axillary levels without compromising healthy tissue in the majority of the patients.

A 10-year follow-up of treatment outcomes in patients with early stage breast cancer and clinically negative axillary nodes treated with tangential breast irradiation following sentinel lymph node dissection or axillary clearance

We compare long-term outcomes in patients with node negative early stage breast cancer treated with breast radiotherapy (RT) without the axillary RT field after sentinel lymph node dissection (SLND) or axillary lymph node dissection (ALND). We hypothesize that though tangential RT was delivered to the breast tissue, it at least partially sterilized occult axillary nodal metastases thus providing low nodal failure rates. Between 1995 and 2001, 265 patients with AJCC stages I-II breast cancer were treated with lumpectomy and either SLND (cohort SLND) or SLND and ALND (cohort ALND). Median follow-up was 9.9 years (range 8.3-15.3 years). RT was administered to the whole breast to the median dose of 48.2 Gy (range 46.0-50.4 Gy) plus boost without axillary RT. Chi-square tests were employed in comparing outcomes of two groups for axillary and supraclavicular failure rates, ipsilateral in-breast tumor recurrence (IBTR), distant metastases (DM), and chronic complications. Progression-free survival (PFS) was compared using log-rank test. There were 136/265 (51%) and 129/265 (49%) patients in the SLND and ALND cohorts, respectively. The median number of axillary lymph nodes assessed was 2 (range 1-5) in cohort SLND and 18 (range 7-36) in cohort ALND (P < 0.0001). Incidence of AFR and SFR in both cohorts was 0%. The rates of IBTR and DM in both cohorts were not significantly different. Median PFS in the SLND cohort is 14.6 years and 10-year PFS is 88.2%. Median PFS in the ALND group is 15.0 years and 10-year PFS is 85.7%. At a 10-year follow-up chronic lymphedema occurred in 5/108 (4.6%) and 40/115 (34.8%) in cohorts SLND and ALND, respectively (P = 0.0001). This study provides mature evidence that patients with negative nodes, treated with tangential breast RT and SLND alone, experience low AFR or SFR. Our findings, while awaiting mature long-term data from NSABP B-32, support that in patients with negative axillary nodal status such treatment provides excellent long-term cure rates while avoiding morbidities associated with ALND or addition of axillary RT field.

Recent advances in breast cancer radiotherapy: Evolution or revolution, or how to decrease cardiac toxicity?

Radiation therapy has a major role in the management of breast cancers. However, there is no consensus on how to irradiate and on volume definitions, and there are strong differences in strategies according to different centers and physicians. New treatment protocols and techniques have been used with the principal purpose of decreasing lung and heart toxicity and adapting radiation treatment to patients’ anatomy. There is evidence that indicates internal mammary chain radiotherapy should be used carefully and that high quality techniques should be used for decreasing the dose delivered to the heart. This review of the literature presents the state of the art on breast cancer radiotherapy, with special focus on the indications, techniques, and potential toxicity.

A novel technique for post-mastectomy breast irradiation utilising non-coplanar intensity-modulated radiation therapy

The aim of this study was to investigate if non-coplanar intensity-modulated radiation therapy (IMRT) in the post-mastectomy setting can reduce the dose to normal structures and improve target coverage. We compared this IMRT technique with a standard partial wide tangential (PWT) plan and a five-field (5F) photon-electron plan. 10 patients who underwent left-sided mastectomy were planned to 50.4 Gy using either (1) PWT to cover the internal mammary (IM) nodes and supraclavicular fields, (2) 5F comprising standard tangents, supraclavicular fields and an electron field for the IM nodes or (3) IMRT. The planning target volume (PTV) included the left chest wall, supraclavicular, axillary and IM lymph nodes. No beams were directed at the right lung, right breast or heart. Mean dose-volume histograms were constructed by combining the dose-volume histogram data from all 10 patients. The mean PTV to receive 95% of the dose (V95%) was improved with the IMRT plan to 94.2% from 91.4% (p = 0.04) with the PWT plan and from 87.7% (p = 0.012) with the 5F plan. The mean V110% of the PTV was improved to 3.6% for the IMRT plan from 16.8% (p = 0.038) for the PWT plan and from 51.8% (p = 0.001) for the 5F plan. The mean fraction volume receiving 30 Gy (v30Gy) of the heart was improved with the IMRT plan to 2.3% from 7.5% (p = 0.01) for the PWT plan and 4.9% (p = 0.02) for the 5F plan. In conclusion, non-coplanar IMRT results in improved coverage of the PTV and a lower heart dose when compared with a 5F or PWT plan.

Coverage of axillary lymph nodes in supine vs. prone breast radiotherapy

PURPOSE

To compare the dosimetry of target and normal tissue when tangents with the breast tissue were applied in a subset of breast cancer patients who had undergone computed tomography (CT) planning both supine and prone.

METHODS AND MATERIALS

The CT images of 20 patients who had undergone simulation in supine and prone positions were used for planning. The axillary lymph node regions (level I-III), breast tissue, tumor bed, heart, and bilateral lungs were manually contoured. Standard tangent fields were designed for the whole breast to deliver a prescribed dose of 50 Gy. Dose-volume histograms were compared between the two sets.

RESULTS

In each patient, coverage of breast tissue and tumor bed was readily achieved by either technique. In either position, treatment of the nodal regions was inadequate. On average, the mean dose to the nodal regions for levels I-III was approximately 50% less in the prone as compared with the supine position. The mean ipsilateral lung volume receiving 95% of the prescribed dose was 6.3% in the supine position compared to 0.43% in the prone position. When planned supine, the mean heart volume receiving 30 Gy was 0.56% compared with 0.30% in the prone position.

CONCLUSIONS

Planning in either position was found to achieve adequate coverage of the breast tissue and tumor bed for all patients. Lung was better spared prone. Coverage of axillary nodes was inadequate in either position, but further reduced in the prone vs. supine position. The choice of optimal setup should take into considerations stage and risk of nodal recurrence.

Dose received by the sentinel node volume during tangential radiation therapy to the breast

The dose received by the sentinel node (SN) volume during tangential irradiation was studied on 31 patients. Of the 50Gy prescribed to the breast volume 95% of the SN volume received from 6.9 to 27.5Gy. In 19 patients the SN volume overlapped with the tangential field deep side.

Prone breast irradiation for pendulous breasts

The purpose of this study was to quantify the differences in doses in the organs at risk and to compare the PTV coverage and dose homogeneity of patients with pendulous breasts between prone and supine position. In 10 patients a CT-based treatment plan was made in prone and supine position. Data about dose homogeneity and doses to organs at risk were collected. Dose homogeneity turned out to be better in prone position and doses in organs at risk were lower, but with the current technique, this occurred at the cost of a reduced PTV coverage.

Is the Berg Axillary Lymph Node Categorization Useful in the 3D Environment?

OBJECTIVE

The Berg muscle-based categorization of axillary lymph node location (commonly referred to as levels I, II, and III) was used extensively by pathologists and surgeons to describe the extent of axillary node dissection in breast cancer patients. However, its reproducibility with different arm positions and utility in 3-dimensional radiation treatment planning hasn't been tested.

METHODS

Computed tomography scans were observed in 16 patients in 2 positions: historical position (HP), ipsilateral arm abducted 90 degrees to the body axis; standard position (SP), arms above head. The volume, contents, and location of Berg lymph node levels (LNL) and the location of lymph nodes, surgical clips, pectoral muscles, and vascular structures relative to reference points were compared.

RESULTS

From HP to SP there was no difference in LNL volumes. However, if measured from an anatomic landmark, the third thoracic vertebra (T3), LNL position varied: level I, an average of 23.1 mm anteriorly, P < 0.01; level II, 7.5 mm medially, P = 0.04; level III, 18.8 mm medially, P = 0.05. Using T3 as a reference: pectoralis major and minor muscles displaced medially (23.9 mm, P < 0.01 and 7.5 mm, P = 0.09) and anteriorly (18.2 mm, P < 0.01 and 11.2 mm, P < 0.01); axillary (18.0 mm, P < 0.01), subscapular (25.4 mm, P < 0.01), and lateral thoracic (8.4 mm, P < 0.01) vessels displaced anteriorly; axillary vessels displaced also medially (15.1 mm, P = 0.03). Disagreements in LN coverage with changes in arm position were observed in 60% (LNs) and 66% (clips) for level II.

CONCLUSIONS

Surgeons, radiologists, and radiation oncologists should be aware that LNL coverage based on muscle boundaries varies significantly with arm position changes, making objective comparisons of information collected in different arm positions unreliable.

Radiation therapy after breast-conserving surgery

The authors critically reviewed previous articles concerning the significance of breast irradiation following breast-conserving surgery in terms of the following subject items: indications for breast-conserving therapy, the significance and complications of breast irradiation, the timing of the start of breast irradiation, the significance of boost irradiation, the potential improvement of survival with systemic therapy plus breast irradiation, the significance of axillary dissection, indications and the significance of regional nodal irradiation, accelerated hypofractionated radiotherapy, omission of breast irradiation in low-risk patients, and future directions. In addition, our previously reported results of breast irradiation following breast-conserving surgery at the Keio University Hospital are outlined. Our newly developed tangential irradiation technique directed to the axilla and a recently introduced three-dimensional simulation technique for radiotherapy treatment planning are also presented.

The effect of simulation on recurrence after breast-conserving surgery and radiotherapy: preliminary results

PURPOSE

To evaluate the effect of the simulation method on recurrence among the patients who received radiotherapy after breast-conserving surgery (BCS) for early breast carcinoma.

MATERIALS AND METHODS

Between 1995 and 2000, 70 patients with stage I-II breast carcinoma underwent breast-conserving surgery and adjuvant radiotherapy. Twenty nine patients (41.4%) were simulated with the 2D contour-based method (September 1995 to August 1997) and 41 patients (58.6%) were simulated with the 3D CT-based method (September 1997 to February 2000). To analyze the effect of the simulation method, the patient and treatment characteristics were compared.

RESULTS

The characteristics were similar for the patients between the 2D contour-based simulation group and the 3D CT-based simulation group. During a median follow-up period of 75 months, 4 (13.8%) of 29 patients who were treated with 2D simulation and 1 (2.4%) of 41 patients who were treated with 3D simulation group developed treatment failure. The five-year survival rates were 89.2% and 95.1% between the 2D and 3D simulation groups (p=0.196). The five-year disease free survival (DFS) rates were 86.2% and 97.5% between the 2D and 3D simulation groups (p=0.0636). On univariate analysis, age > 40 (p= 0.0226) and the number of dissected axillary lymph node >or= 10 (p=0.0435) were independent predictors of improved 5-year DFS.

CONCLUSIONS

Although our data showed marginal significance for the DFS between the two groups, it is insufficient, due to the small number of patients in our study, to prove whether 3D CT-based simulation might improve the DFS and reduce the risk of recurrence when compared with 2D contour-based simulation. Further study is needed with a larger group of patients.

Quality assurance in the EORTC phase III randomised 'boost vs. no boost' trial for breast conserving therapy: comparison of the results of two individual case reviews performed early and late during the accrual period

BACKGROUND AND PURPOSE

To evaluate the impact of quality assurance on treatment compliance, we compared the outcome of the two individual case reviews (ICR) conducted early and late during the accrual period of a large prospective multi-centre trial.

PATIENTS AND METHODS

At the onset of the trial, medical files of five patients from each participating centre were evaluated for the compliance to the protocol for eligibility, surgery, pathology and radiotherapy and for the quality of reporting of the data on the case report forms. In nine major centres, this procedure was repeated near the end of the trial.

RESULTS

Both in the early and the late ICR, we found a very limited number of deviations from the guidelines for eligibility, staging, surgery, and pathology. Compliance to radiotherapy requirements was good with the exception of a too low minimal dose in 30% and the lack of target volume delineation in the majority of the evaluated patients. The comparison of the late with the early ICR demonstrated an improvement of the quality of data reporting by 6% and of target volume delineation from 33 to 53%.

CONCLUSIONS

The initial ICR has lead to the identification of a number of parameters, which needed a clarification in the protocol. These items have been corrected and the individual institutions have been made aware of the necessary adaptations. The evaluation at the end of the trial period showed that there was an improvement but also showed that continuous monitoring is necessary, especially for institutions which have the most deviations in the first ICR.

Comparaison simulation classique–simulation virtuelle au cours d'une irradiation mammaire : étude prospective sur 14 patientes

PURPOSE

To compare conventional 2D simulation and virtual simulation on 14 patients with breast cancer.

PATIENTS AND METHODS

Patients were simulated for treatment using standard procedure. They subsequently underwent CT scan in the treatment position. The CTV was defined as breast tissue. The PTV was obtained by adding a 3D margin of 1 cm around CTV. Organs at risk (lungs and heart) were outlined. Ballistics and dose distribution obtained with the two planning methods were compared.

RESULTS

With conventional simulation, 95% of CTV received 95% of the dose prescribed. Virtual simulation significantly improved dosimetric coverage of PTV without increasing irradiation volume of lung and heart. In 2D simulation, using three slices allowed optimisation by adjusting wedge angle. The five-slice plan was a much better predictor of the maximum dose regions when compared to the three-slice plan. Using entire CT data didn't give any benefit.

CONCLUSION

Variations in CTV delineation and PTV definition limit interest of virtual simulation. In classic simulation, a 5 CT slice-plan can be used to optimise dose distribution.

Interobserver variability of clinical target volume delineation of glandular breast tissue and of boost volume in tangential breast irradiation

BACKGROUND AND PURPOSE

To determine the interobserver variability of clinical target volume delineation of glandular breast tissue and of boost volume in tangential breast irradiation.

PATIENTS AND METHODS

Eighteen consecutive patients with left sided breast cancer treated by breast conserving surgery agreed to participate in our study. Volumes of the glandular breast tissue (CTV breast) and of the boost (CTV boost) were delineated by five observers. We determined 'conformity indices' (CI) and the ratio between the volume of each CTV and the mean volume of all CTVs (CTV ratio). Subsequently we determined the most medial, lateral, anterior, posterior, cranial and caudal extensions both of CTV breast and CTV boost for all observers separately.

RESULTS

The mean CI breast was 0.87. For one observer we noted the highest CTV ratio in 17 out of 18 cases. No association was noted between CI breast and menopausal status. The mean CI boost was 0.56. We did not find a relation between the presence or absence of clips and the CI boost. For another observer we noted the lowest CTV boost ratio in 10 out of 17 cases.

CONCLUSIONS

We recommend that each institute should determine its interobserver variability with respect to CTV breast and CTV boost before implementing the delineation of target volumes by planning CT in daily practice.

HDR brachytherapy combined with 3-D conformal vs. IMRT in left-sided breast cancer patients including internal mammary chain: comparative analysis of dosimetric and technical parameters

Treatment of the internal mammary chain (IMC) with radiation therapy (RT) for patients with breast cancer remains a controversial issue. Different treatment techniques have been proposed, including oblique electrons, electron‐photon combination, and partially wide tangents (PWTs). However, the residual heart dose can remain significant mainly for left‐sided lesions. With PWTs and intensity‐modulated radiotherapy (IMRT), respiratory movement and errors in IMC localization remain a problem. The goal of this paper is to evaluate the impact of IMC brachytherapy (IMCBT) combined with 3D conformal radiotherapy (3DCRT) planning on heart, lung, and contralateral breast doses compared with IMRT. All plans including IMCBT plus 3DCRT were done on PLATO; IMRT plans were generated using the Cadplan‐Helios inverse treatment‐planning software module with the “sliding window&rdquo; technique. Dose‐volume histograms (DVHs) were calculated for all volumes of interest. Conformity and homogeneity index was also calculated for the planning target volume (PTV). Dose distribution in the surrounding normal tissue was evaluated. The mean conformity of the PTV was found to be 1.06 with IMCBT plus 3DCRT and 1.12 with IMRT. The mean homogeneity (HI95/107) was found to be 1.4 with IMCBT plus 3DCRT and 3.32 with IMRT. Using the IMCBT plus 3DCRT technique, the mean dose to the heart, contralateral breast, ipsilateral lung, and contralateral lung decreased with values of 32%, 6.76%, 20% and 5.52%, respectively, compared with IMRT. This novel technique of IMCBT plus 3DCRT can potentially reduce the dose to the heart and lungs. In addition, it rivals IMRT because of its unique advantages in localization, obviating the need for respiratory gating and maximum sparing of heart and other structures.

PACS numbers: 87.53.Jw, 87.53.Kn, 87.53.Mr, 87.53, 87.53.Tf

Irradiation with standard tangential breast fields in patients treated with conservative surgery and sentinel node biopsy: using a three-dimensional tool to evaluate the first level coverage of the axillary nodes

Recent data show that axillary coverage can be obtained, but only through a selective CT-based treatment planning, as standard tangential fields are inadequate to deliver therapeutic doses. Currently, the replacement of axillary dissection with new techniques, such as sentinel node (SN) biopsy, makes it necessary to re-address the question about the real role of axillary irradiation, complicated by the differences in the anatomy of dissected and undissected axillary regions. The purpose of this paper is the dosimetric analysis of first axillary level coverage in standard irradiation of 15 breast-cancer patients treated with quadrantectomy and SN biopsy (negative finding). During surgery a clip on the site of the SN was positioned, marking the caudal margin of first axillary level. After the breast treatment plan was completed, the first axillary level was contoured on CT scans, from the site of the surgical clip up to the sternal manubrium, for coverage analysis with dose-volume histograms (DVHs) and three-dimensional isodose visualization. The maximum dose mean ranged from 5% to 80% of the prescribed dose (mean value 48.7%). The mean total dose received by the volume of interest was lower than 40 Gy in all but one patient. No patient had total irradiation of first nodal level; only one patient had 35% of the volume enclosed in the 100% isodose. Our analysis lead to the conclusion that therapeutic doses are not really delivered to first level axillary level nodes by a standard tangential field technique, and that specific treatment planning and beam arrangement are required when adequate coverage is necessary.

Axillary lymph node dose with tangential breast irradiation

PURPOSE

The advent of sentinel lymph node mapping and biopsy in the staging of breast cancer has resulted in a significant decrease in the extent of axillary nodal surgery. As the extent of axillary surgery decreases, the radiation dose and distribution within the axilla becomes increasingly important for current therapy planning and future analysis of results. This analysis examined the radiation dose distribution delivered to the anatomically defined axillary level I and II lymph node volume and surgically placed axillary clips with conventional tangential breast fields and CT-based three-dimensional (3D) planning.

METHODS AND MATERIALS

Fifty consecutive patients with early-stage breast cancer undergoing breast conservation therapy were evaluated. All patients underwent 3D CT-based planning with conventional breast tangential fields designed to encompass the entire breast parenchyma. Using CT-based 3D planning, the dose distribution of the standard tangential breast irradiation fields was examined in relationship to the axillary level I and II lymph node volumes. Axillary level I and II lymph node anatomic volumes were defined by CT and surgical clips placed during complete level I-II lymph node dissection. Axillary level I-II lymph node volume doses were examined on the basis of the prescribed breast radiation dose and 3D dose distribution.

RESULTS

All defined breast volumes received > or =95% of the prescribed dose. By contrast, the 95% isodose line encompassed only an average of 55% (range, 23-87%) of the axillary level I-II lymph node anatomic volume. No patient had complete coverage of the axillary level I-II lymph node region by the 95% isodose line. The mean anatomic axillary level I-II volume was 146.3 cm(3) (range, 83.1-313.0 cm(3)). The mean anatomic axillary level I-II volume encompassed by the 95% isodose line was 84.9 cm(3) (range, 25.1-219.0 cm(3)). The mean 95% isodose coverage of the surgical clip volume was 80%, and the median value was 81% (range, 58-98%). The mean volume deficit between the axillary level I-II volume and the surgical clip volume was 41.7 cm(3) (median, 30.0 cc).

CONCLUSION

In this study, standard tangential breast radiation fields failed to deliver a therapeutic dose adequately to the axillary level I-II lymph node anatomic volume. No patient received complete coverage of the axillary level I-II lymph node volume. Surgically placed axillary clips also failed to delineate the level I-II axilla adequately. Definitive irradiation of the level I and II axillary lymph node region requires significant modification of standard tangential fields, best accomplished with 3D treatment planning, with specific targeting of anatomically defined axillary lymph node volumes as described, in addition to the breast parenchymal volumes.

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.

Treatment of breast carcinoma in patients with clinically negative axillary lymph nodes using radiotherapy versus axillary dissection

BACKGROUND

The role of axillary lymph node dissection (AxD) for patients with breast carcinoma who have clinically negative lymph nodes (cN0) and undergo breast-conserving therapy has been controversial. If patients do not undergo AxD, then it is uncertain whether specific lymph node irradiation should be given. The authors compared the results obtained from patients w ho underwent AxD with the results from patients who received axillary irradiation (AxR) using one of two radiotherapy techniques.

METHODS

Patients with T1-T2cN0 breast carcinoma were treated from 1983 to 2002 with either AxD (80 patients) or AxR (1134 patients received tangential-field [2-field] irradiation, and 303 patients received 3-field irradiation). The median follow-up was 161 months for the AxD group and 66 months for the AxR group (55 months for patients who received tangential-field irradiation, and 122 months for patients who received 3-field irradiation).

RESULTS

One patient in the AxD group and 35 patients in the AxR group had axillary recurrences. The 10-year cumulative axillary recurrence rates were 1.3% and 4.6% for the AxD group and the AxR group, respectively (P = 0.21). For patients with T1 tumors, the 10-year overall survival rates for the two groups were 94.7% and 92.7%, respectively (P = 0.34); and, for patients with T2 tumors, the 10-year overall survival rates were 92.5% and 89.1%, respectively (P = 0.34). In the AxR group, the 5-year axillary recurrence rates were 2.5% for patients who received tangential-field irradiation and 1.7% for patients who received 3-field irradiation (P = 0.18), and the 5-year regional recurrence rates for the two groups were 4.8% and 2.4%, respectively (P = 0.048). On multivariate analysis, positive lymphovascular invasion, outer tumor location, and larger tumor size were significant risk factors for regional failure.

CONCLUSIONS

For patients with cN0 breast carcinoma, AxD and AxR yielded the same overall survival rates. Most patients can be treated safely with tangential-field irradiation alone. Patients who are at increased risk of regional failure may benefit from three-field irradiation.

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

BACKGROUND AND PURPOSE

As the location of the regional lymph nodes (LNs) of the breast varies largely between patients and may be dependant on the position of the arm, adequate localization of these nodes is mandatory in order to fully take advantage of optimized conformal radiotherapy. For this purpose, the anatomical boundaries of the regional lymph node (LN) clinical target volumes (CTVs) for delineation on transverse CT-slices, made in treatment position, were established.

PATIENTS AND METHODS

Anatomical and surgical descriptions of the regional LNs of the breast, as well as a shoulder dissection, were studied. Axial slices of a human cadaver with one arm in abduction and the other in adduction were investigated, to assess the displacement of LNs by abduction of the arm into treatment position. Based on these findings, we defined the anatomical boundaries of the regional LN CTVs visible on transverse CT-slices.

RESULTS

Standard anatomical and surgical descriptions appeared to be inadequate for determination of the boundaries of the regional LN CTVs in treatment position. With abduction of the arm, a change in position of all regional LNs, except for the medial supraclavicular LNs and internal mammary LNs, was observed in the anatomical cross-sections. This was also taken into account in our delineation protocol proposal.

CONCLUSIONS

Anatomically based guidelines for delineation of the regional LN CTVs for loco-regional irradiation of the breast on transverse CT-slices, made in treatment position, have been developed in this study. These could be used as a basis for conformal radiotherapy.