Electron arc irradiation of the postmastectomy chest wall: clinical results

Heart-sparing radiotherapy with three-dimensional printing technology after mastectomy for patients with left breast cancer

The purpose of this study was to analyze the effectiveness of electron beam therapy (EBT) with patient-tailored bolus (PTB) using three-dimensional printing technology to reduce heart and lung doses during post-mastectomy radiotherapy (PMRT). For 28 patients with left breast cancer, we designed customized virtual bolus for PMRT to compensate for surface irregularities on computed tomography images and developed optimized plans for EBT. As comparison between the PTB and tangential plans, the PTB plan reduced unnecessary exposure to heart and ipsilateral lung with better target coverage compared with the tangential technique.

Comparison of Chest Wall and Lymphatic Radiotherapy Techniques in Patients with Left Breast Carcinoma

OBJECTIVE

The aim of this study was to find the most appropriate technique for postmastectomy chest wall (CW) and lymphatic irradiation.

MATERIALS AND METHODS

Partially wide tangent, 30/70 photon/electron mix, 20/80 photon/electron mix and CW and internal mammary en face electron field, were studied on computerized tomography (CT) scans of 10 left breast carcinoma patients and dosimetric calculations have been studied. Dose volume histograms (DVH) obtained from treatment planning system (TPS) were used for minimal, maximal and mean doses received by the clinical target volumes and critical structures.

RESULTS

Partially wide tangent field resulted in the most homogeneous dose distribution for the CW and a significantly lower lung and heart doses compared with all other techniques. However, right breast dose was significantly higher for partially wide tangent technique than that each of the other techniques. Approximately 0.6-7.9% differences were found between thermoluminescent dosimeter (TLD) and treatment planning system (TPS). The daily surface doses calculating using Gafchromic® external beam therapy (EBT) dosimetry films were 161.8±2.7 cGy for the naked, 241.0±1.5 cGy when 0.5 cm bolus was used and 255.3±2.7 cGy when 1 cm bolus was used.

CONCLUSION

As a result of this study, partially wide tangent field was found to be the most appropriate technique in terms of the dose distribution, treatment planning and set-up procedure. The main disadvantage of this technique was the higher dose to the contralateral breast comparing the other techniques.

Electron arc therapy for bilateral chest wall irradiation: treatment planning and dosimetric study

AIMS

The treatment of patients with synchronous bilateral breast cancer is a challenge. We present a report of dosimetric data of patients with bilateral chest walls as the target treated with electron arc therapy.

MATERIALS AND METHODS

Ten consecutive patients who had undergone electron arc therapy to the bilateral chest wall for breast cancer were analysed. After positioning and immobilisation, patients underwent computed tomography scans from the neck to the upper abdomen. Electron arc plans were generated using the PLATO RTS (V1.8.2 Nucletron) treatment planning system. Electron energy was chosen depending upon the depth and thickness of the planning target volume (PTV). For all patients, the arc angle ranged between 80 and 280° (start angle 80°, stop angle 280°). The homogeneity index, coverage index and doses to organs at risk were evaluated. The patient-specific output factor and thermoluminescence dosimetry (TLD) measurements were carried out for all patients. The total planned dose to the PTV was 50Gy/25 fractions/5 weeks.

RESULTS

The mean PTV (± standard deviation) was 568.9 (±116)cm(3). The mean PTV coverage was 89 (±5.8)% of the prescribed dose. For the right lung, the mean values of D(1) and D(10) were 46 (±7.6) and 30 (±9)Gy, respectively. For the left lung, the mean values of D(1) and D(10) were 45 (±7) and 27 (±8)Gy, respectively. For the heart, the mean values of D(1), D(5) and D(10) were 21 (±15), 13.5 (±12) and 9 (±9)Gy, respectively. The mean values of TLD at various pre-specified locations on the chest wall surface were 1.84, 1.82, 1.82, 1.89 and 1.78Gy, respectively

CONCLUSION

The electron arc technique for treating the bilateral chest wall is a feasible and pragmatic technique. This technique has the twin advantages of adequate coverage of the target volume and sparing of adjacent normal structures. However, compared with other techniques, it needs a firm quality assurance protocol for dosimetry and treatment delivery.

Monte Carlo calculation of monitor unit for electron arc therapy

PURPOSE

Monitor unit (MU) calculations for electron are therapy were carried out using Monte Carlo simulations and verified by measurements. Variations in the dwell factor (DF), source-to-surface distance (SSD), and treatment are angle (a) were studied. Moreover, the possibility of measuring the DF, which requires gantry rotation, using a solid water rectangular, instead of cylindrical, phantom was investigated.

METHODS

A phase space file based on the 9 MeV electron beam with rectangular cutout (physical size = 2.6 x 21 cm2) attached to the block tray holder of a Varian 21 EX linear accelerator (linac) was generated using the EGSnrc-based Monte Carlo code and verified by measurement. The relative output factor (ROF), SSD offset, and DF, needed in the MU calculation, were determined using measurements and Monte Carlo simulations. An ionization chamber, a radiographic film, a solid water rectangular phantom, and a cylindrical phantom made of polystyrene were used in dosimetry measurements.

RESULTS

Percentage deviations of ROF, SSD offset, and DF between measured and Monte Carlo results were 1.2%, 0.18%, and 1.5%, respectively. It was found that the DF decreased with an increase in a, and such a decrease in DF was more significant in the a range of 0 degrees-60 degrees than 60 degrees-120 degrees. Moreover, for a fixed a, the DF increased with an increase in SSD. Comparing the DF determined using the rectangular and cylindrical phantom through measurements and Monte Carlo simulations, it was found that the DF determined by the rectangular phantom agreed well with that by the cylindrical one within +/- 1.2%. It shows that a simple setup of a solid water rectangular phantom was sufficient to replace the cylindrical phantom using our specific cutout to determine the DF associated with the electron arc.

CONCLUSIONS

By verifying using dosimetry measurements, Monte Carlo simulations proved to be an alternative way to perform MU calculations effectively for electron are therapy. Since Monte Carlo simulations can generate a precalculated database of ROF, SSD offset, and DF for the MU calculation, with a reduction in human effort and linac beam-on time, it is recommended that Monte Carlo simulations be partially or completely integrated into the commissioning of electron are therapy.

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.

Postmastectomy Electron Beam Chest Wall Irradiation in Women With Breast Cancer: A Clinical Step Toward Conformal Electron Therapy

PURPOSE

Electron beam radiotherapy of the chest wall with or without lymph node irradiation has been used at the Institut Curie for >20 years. The purpose of this report was to show the latest improvements of our technique developed to avoid hot spots and improve the homogeneity.

METHODS AND MATERIALS

The study was split into two parts. A new electron irradiation technique was designed and compared with the standard one (dosimetric study). The dose distributions were calculated using our treatment planning software ISIS (Technologie Diffusion). The dose calculation was performed using the same calculation parameters for the new and standard techniques. Next, the early skin toxicity of our new technique was evaluated prospectively in the first 25 patients using Radiation Therapy Oncology Group criteria (clinical study).

RESULTS

The maximal dose found on the five slices was 53.4 +/- 1.1 Gy for the new technique and 59.1 +/- 2.3 Gy for the standard technique. The hot spots of the standard technique plans were situated at the overlap between the internal mammary chain and chest wall fields. The use of one unique field that included both chest wall and internal mammary chain volumes solved the problem of junction. To date, 25 patients have been treated with the new technique. Of these patients, 12% developed Grade 0, 48% Grade 1, 32% Grade 2, and 8% Grade 3 toxicity.

CONCLUSIONS

This report describes an improvement in the standard postmastectomy electron beam technique of the chest wall. This new technique provides improved target homogeneity and conformality compared with the standard technique. This treatment was well tolerated, with a low rate of early toxicity events.

Multivariate analyses of locoregional recurrences and skin complications after postmastectomy radiotherapy using electrons or photons

PURPOSE

We retrospectively analyzed factors of locoregional (LR) recurrence and skin complications in patients after postmastectomy radiotherapy (PMRT).

METHODS AND MATERIALS

From January 1988 to December 1999, a total of 246 women with Stage II and III breast cancer received PMRT. Doses of 46 to 52.2 Gy/23 to 29 fractions were delivered to the chest wall (CW) and peripheral lymphatic drainage with 12 to 15 MeV single-portal electrons or 6MV photons. Of the patients, 84 patients received an additional 6 to 20 Gy boost to the surgical scar using 9 MeV electrons. We used the Cox regression model for multivariate analyses of CW, supraclavicular nodes (SCN), and LR recurrence.

RESULTS

N3 stage (positive nodes >9) (p = 0.003) and diabetes (p = 0.004) were independent factors of CW recurrence. Analysis of ipsilateral SCN recurrence showed that N3 stage (p < 0.001) and electrons (p = 0.006) were independent factors. For LR recurrence, N3 (p < 0.001), T3 to T4 (p = 0.033) and electrons (p = 0.003) were significant factors. Analysis of skin telangiectasia revealed that electrons (p < 0.001) and surgical scar boost (p = 0.003) were independent factors.

CONCLUSIONS

Photons are superior to single-portal electrons in patients receiving postmastectomy radiotherapy because of better locoregional control and less skin telangiectasia. In patients in whom the number of positive axillary nodes is >9, more aggressive treatment may be considered for better locoregional control.

Application of the electron pencil beam redefinition algorithm to electron arc therapy

This project investigated the potential of summing fixed-beam dose distributions calculated using the pencil-beam redefinition algorithm (PBRA) at small angular steps (1 degree) to model an electron arc therapy beam. The PRBA, previously modified to model skin collimation, was modified further by incorporating two correction factors. One correction factor that is energy, SSD (source-to-surface distance), and field-width dependent constrained the calculated dose output to be the same as the measured dose output for fixed-beam geometries within the range of field widths and SSDs encountered in arc therapy. Another correction factor (single field-width correction factor for each energy) compensated for large-angle scattering not being modeled, allowing a more accurate calculation of dose output at mid arc. The PBRA was commissioned to accurately calculate dose in a water phantom for fixed-beam geometries typical of electron arc therapy. Calculated central-axis depth doses agreed with measured doses to within 2% in the low-dose gradient regions and within 1-mm in the high-dose gradient regions. Off-axis doses agreed to within 2 mm in the high-dose gradient regions and within 3% in the low-dose gradient regions. Arced-beam calculations of dose output and depth dose at mid arc were evaluated by comparing to data measured using two cylindrical water phantoms with radii of 12 and 15 cm at 10 and 15 MeV. Dose output was measured for all combinations of phantom radii of curvature, collimator widths (4, 5, and 6 cm), and arc angles (0 degrees, 20 degrees, 40 degrees, 60 degrees, 80 degrees, and 90 degrees) for both beam energies. Results showed the calculated mid-arc dose output to agree within 2% of measurement for all combinations. For a 90 degree arc angle and 5 x 20 cm2 field size, the calculated mid-arc depth dose in the low-dose gradient region agreed to within 2% of measurement for all depths at 10 MeV and for depths greater than depth of dose maximum R100 at 15 MeV. For depths in the buildup region at 15 MeV the calculations overestimated the measured dose by as much as 3.4%. Mid-arc depth dose in the high-dose gradient region agreed to within 2.2 mm of measured dose. Calculated two-dimensional relative dose distributions in the plane of rotation were compared to dose measurements using film in a cylindrical polystyrene phantom for a 90 degree arc angle and field widths of 4, 5, and 6 cm at 10 and 15 MeV. Results showed that off-axis dose at the ends of arc (without skin collimation) agreed to within 2% in the low-dose gradient region and to within 1.2 mm in the high-dose gradient region. This work showed that the accuracy of the PBRA arced-beam dose model met the criteria specified by Van Dyk et al. [Int. J. Radiat. Oncol. Biol. Phys. 26, 261-273 (1993)] with the exception of the buildup region of the 15 MeV beam. Based on the present results, results of a previous study showing acceptable accuracy in the presence of skin collimation, and results of a previous study showing acceptable accuracy in the presence of internal heterogeneities, it is concluded that the PBRA arced-beam dose model should be adequate for planning electron arc therapy.

Immediate Breast Reconstruction can Impact Postmastectomy Irradiation

OBJECTIVE

Immediate breast reconstruction is an attractive option for patients who undergo mastectomy. The purpose of this study was to qualitatively assess the effect of immediate reconstruction on the design of postmastectomy radiotherapy fields at our institution.

METHODS

We retrospectively reviewed the records of 152 patients treated at our institution with postmastectomy radiotherapy over a 1-year period. We identified 18 postmastectomy radiotherapy plans in the setting of prior reconstruction. By consensus, 2 board-certified radiation oncologists scored the 18 plans in terms of 4 outcomes: coverage of the chest wall breadth, coverage of the ipsilateral internal mammary chain (IMC) region, minimization of lung exposure, and avoidance of the heart.

RESULTS

Only 4 of the 18 plans resulted in optimal treatment of the chest wall breadth and IMC region while well avoiding the heart and lung. Of the remaining 14 plans, 12 compromised coverage of the chest wall breadth medially and/or laterally, and 9 provided no IMC coverage.

CONCLUSION

Immediate breast reconstruction may impose limitations on the treatment planning of postmastectomy radiotherapy, particularly in regard to providing broad coverage of the chest wall and IMC region while avoiding excess exposure of the heart and lung.

An improved internal mammary irradiation technique in radiation treatment of locally advanced breast cancers

The purpose of the present study was to compare a new internal mammary irradiation technique with traditional techniques for locally advanced breast cancers in terms of sparing ipsilateral lung and heart and reducing the “cold” and “hot spots” in breast tissue. The new technique uses wide tangential fields for the first eight fractions of treatment. A medial internal mammary field (IMF) of electrons matched with narrowed tangential fields is used for the remaining fractions. Intensity‐modulated radiation therapy (IMRT) by means of segmented multileaf collimation (SMLC) is used in the narrowed tangential fields to improve the match between the electron and the photon fields. Treatment planning was performed to compare this technique to a wide‐tangential‐only technique and to a traditional oblique IMF technique for three patients with differing habitus. Film dosimetry was performed in a solid water phantom to confirm the planning results. For all three patients, the mean doses of the ipsilateral lung and the heart were significantly reduced with the new technique. The lung and the heart volumes were remarkably reduced at low‐dose levels (≤12GY) compared to the traditional IMF technique, and significantly reduced at all dose levels compared to the wide tangential technique. The new technique also reduced the “cold” and “hot spots” along the match plane between the IMF and the tangential fields compared to the traditional IMF technique. In conclusion, the new IMF technique shows dosimetric improvement compared to the traditional IMF technique in terms of the critical organ sparing and target dose uniformity.

PACS number: 87.53.Tf

Postmastectomy electron-beam chest-wall irradiation in women with breast cancer

PURPOSE

This retrospective study evaluates the results of postmastectomy electron-beam chest-wall irradiation in patients with breast cancer.

METHODS AND MATERIALS

From 1980 to 1994, 144 women with localized breast cancer received postmastectomy radiotherapy. The chest wall was irradiated by electron beam, 6 to 12 MeV energy, depending on wall thickness, 2.0 Gy daily, 5 times/week for total dose of 50 Gy. Forty-one patients received 16-Gy boosts to the mastectomy scar. In addition, the supraclavicular and axilla areas were irradiated by anterior field with 6-MV photon beam.

RESULTS

Median follow-up was 84 months. Fifteen patients (10%) had local-regional recurrence (LRR) and 57 patients (40%) had systemic relapse (SR). Median time from mastectomy to LRR was 20 months and median time to SR was 33 months. Axillary lymph nodes status influenced both LRR and SR. LRR rate was 0% in N0 and 12% in N1 disease; SR rate was 14% in N0 and 45% in N1 disease. Disease-free and overall survival was 58% and 67% in 10 years and 50% and 55% in 20 years, respectively. No cardiac toxicity was related to left chest-wall irradiation.

CONCLUSION

Postmastectomy electron-beam chest-wall irradiation is as effective as photon-beam irradiation in breast cancer.

Local???Regional Radiation Therapy After Breast Reconstruction: What Is the Appropriate Target Volume?

The oncologic safety and cosmetic outcome of immediate breast reconstruction in breast cancer patients requiring radiation therapy remains ill-defined. Between 1980 and 1998, 18 patients were treated at the University of Utah Medical Center with mastectomy, immediate breast reconstruction, and adjuvant radiation therapy delivered via an electron arc technique. A case-control study was performed matching reconstructed patients in a 1:2 ratio with patients undergoing mastectomy without reconstruction, using number of lymph nodes and tumor size. Median follow-up was 61 months for the reconstructed group. Five-year local-regional control, disease-free survival, and overall survival rates were 87%, 58%, and 74% respectively in the reconstructed group, versus 88%, 57%, and 67% respectively in the matched control group. Cosmesis was good/excellent in 11 of 13 living patients (85%). Significant capsular contraction occurred in 18% of prosthetic reconstruction patients, and revisional surgery was required in 24% of prosthetic reconstruction patients. Utilizing the electron arc technique, the median radiation dose to the chest wall at the midlevel of the ribs was 20% of the prescribed dose, and no patient failed deep to the implant. These results suggest that in appropriately selected patients, structures deep to the reconstruction are not at high risk for local-regional recurrence, and immediate breast reconstruction yields comparable local-regional control, disease-free survival, and overall survival rates to nonreconstructed patients, with acceptable cosmetic results.

Electron arc irradiation of the postmastectomy chest wall in locally recurrent and metastatic breast cancer

The purpose of this study was to evaluate local-regional control and overall survival in women with locally recurrent and metastatic breast cancer (MBC) treated with postmastectomy electron arc therapy. Postmastectomy electron arc irradiation was used to treat 39 women with isolated local-regional recurrence of breast cancer following mastectomy, and 14 patients with MBC who had, or who were at high risk of, local-regional recurrence. After computed tomography treatment planning, patients were treated with electron arc radiotherapy to a median dose of 59.3 Gy. The median follow-up for alive patients was 45.4 months. For patients with local-regional recurrence, the 5-year local-regional control and overall survival rates were 74% and 43%, respectively. The 2-year overall survival was greater for those patients with a disease-free interval greater than 24 months when compared to patients with a disease-free interval less than 24 months (83% vs. 60%, respectively); however, the median survival was not significantly different (57.6 and 58.6 months, respectively). Patients with a solitary nodule at recurrence had an improved 5-year overall survival of 58% compared with 40% for patients with multiple lesions. For patients with metastatic disease, the 5-year local-regional control and overall survival rates were 76% and 31%, respectively. Local-regional control can be achieved in the majority of patients with local-regionally recurrent breast cancer (74%) or MBC (76%) who had, or who were, at high risk of local-regional recurrence treated with postmastectomy electron arc irradiation.

Predictors for pneumonitis during locoregional radiotherapy in high-risk patients with breast carcinoma treated with high-dose chemotherapy and stem-cell rescue

BACKGROUND

To study the predictive value of serial pulmonary function testing (PFT) for toxicity in patients who have received high-dose chemotherapy (HDCT) and stem-cell rescue for breast carcinoma. These patients are at risk of developing therapy-related pneumonitis (TRP) during or after radiotherapy (RT).

METHODS

Sixty-eight patients who received induction chemotherapy (CT) and consolidation HDCT (cyclophosphamide, cisplatin, carmustine) underwent serial PFTs before induction CT, after HDCT, and before locoregional RT. The rate of TRP, i.e., pulmonary complications of Grade 2 or higher (World Health Organization classification), was studied during and 2 months after RT. We analyzed the time-course of changes in the diffusing capacity of carbon monoxide (DLCO) and forced expiratory volume at one second (FEV(1)) and studied the differences between patients who developed TRP and those who did not.

RESULTS

The incidence of TRP was 46%. There were marked reductions in DLCO and FEV(1) at the time of RT compared with baseline (Wilcoxon signed rank test: P < 0.001). However, pre-RT PFT values did not predict subsequent development of TRP. Instead, the ratio of pre-RT DLCO to the minimum post- HDCT DLCO, i.e., trend of improvement, predicted the development of TRP in patients (logistic regression analysis: P = 0.048). At a cutoff level of 1, the positive and negative predictive values for this ratio were 61% and 87%, respectively. There was an association between this ratio and a longer interval between HDCT and RT (Spearman rank correlation: P = 0.002).

CONCLUSIONS

The results suggest that the directional trend of DLCO after HDCT, i.e., no recovery from nadir values, is a predictor for TRP. TRP patients have a shorter median interval between HDCT and RT than asymptomatic patients. To minimize the occurrence of TRP, one should consider either delaying RT beyond 2 months following carmustine-based HDCT to allow the PFTs to partly recover, or confirm apositive directional trend for improvement of DLCO at the start of RT compared to the post-HDCT nadir value.

Predictive factors for skin telangiectasia following post-mastectomy electron beam irradiation

This study evaluated the predictive factors associated with skin telangiectasia following post-mastectomy electron beam irradiation of the chest wall and regional lymph nodes in patients with breast cancer. From July 1987 to December 1994, 120 women with stages II and III breast cancer received electron beam irradiation following modified radical mastectomy. Doses of 50-50.4 Gy per 25-28 fractions were given to the chest wall (with bolus), the internal mammary nodes, the supraclavicular nodes and the axillary lymph nodes using a 12 MeV or 15 MeV single portal electron beam. 19 patients received an additional 10-16 Gy boost to the surgical scar using a 9 MeV electron beam. Univariate and multivariate analyses for the development of skin telangiectasia showed 5- and 7-year actuarial rates of telangiectasia to be 59% and 72%, respectively. In univariate analysis, an additional surgical scar boost (p=0.023) as well as no treatment interruption (p=0.028) were associated with a significantly increased risk of skin telangiectasia. In multivariate analysis, the only significant independent factor for the development of skin telangiectasia was surgical scar boost (p=0.026); no treatment interruption showed a trend but did not achieve significance (p=0.051). Thus, patients given an additional boost to the surgical scar are more likely to develop skin telangiectasia. Shorter treatment courses may result in a higher probability of skin telangiectasia following electron beam irradiation.

Implementing a tantalum wire mesh to increase the skin dose in low-energy electron irradiation of the chest wall

Radiation treatment of the post-mastectomy chest wall is performed in our institution by straight-on electron irradiation. The chest-wall thickness is measured and the beam energy is chosen so that the chest wall is treated to therapeutic doses, while sparing the underlying lung tissue. The most commonly chosen energies are 6 and 9 MeV. The skin dose should be 90% of the dose prescribed to the chest wall, which is higher than can be achieved with 6- and 9-MeV beams because of the low surface dose. The addition of a bolus slab during part of the treatment can correct for this; however, the added depth means that a higher energy has to be chosen, which will increase the lung dose (the higher the electron energy, the slower the falloff of the electron depth-dose curve). A mesh of a high-Z material above the skin gives rise to obliquely scattered and low-energy electrons that effectively spoil the buildup zone. Dosimetric measurements of a Tantalum (Ta) mesh were performed using a dose scanner in a water tank and a film inserted in a humanoid phantom during a simulated treatment. Measurements were also done for the clinically relevant cases of oblique beam incidence and with the mesh placed 1 cm above the surface. The measurements demonstrate the spoiling of the buildup zone, while having only a moderate influence on the dose distribution beyond the dose maximum. The mesh also changes the absolute dose. In a fractionated regime, the first part of the treatment would be without the mesh, adding it only during the latter fractions. The total dose distribution gives 90% to the skin, while leaving the depth-dose characteristics beyond the dose maximum virtually unchanged.

Technical factors associated with radiation pneumonitis after local +/- regional radiation therapy for breast cancer

PURPOSE

To assess the incidence of, and clinical factors associated with, symptomatic radiation pneumonitis (RP) after tangential breast/chest wall irradiation with or without regional lymph node treatment.

METHODS AND MATERIALS

The records of 613 patients irradiated with tangential photon fields for breast cancer with >6 months follow-up were reviewed. Clinically significant RP was defined as the presence of new pulmonary symptoms requiring steroids. Data on clinical factors previously reported to be associated with RP were collected, e.g., tamoxifen or chemotherapy exposure and age. The central lung distance (CLD) and the average of the superior and inferior mid lung distance (ALD) in the lateral tangential field were measured on simulator films as a surrogate for irradiated lung volume. Many patients were treated with partly wide tangential fields that included a heart block shielding a part of the lower lung.

RESULTS

RP developed in 15/613 (2.4%) patients. In the univariate analysis, there was an increased incidence of RP among patients treated with local-regional radiotherapy (RT) (4.1%) vs. those receiving local RT only (0.9%) (p = 0.02), and among patients receiving chemotherapy (3.9%) vs. those not treated with chemotherapy (1.4%) (p = 0.06). According to multivariate analysis, only the use of nodal RT remained independently associated with RP (p = 0.03). There was no statistically significant association between ranked CLD or ALD measurements and RP among patients treated with nodal irradiation with tangential beams. However, there was a statistically nonsignificant trend for increasing rates of RP with grouped ALD values: below 2 cm (4% RP rate), between 2 and 3 cm (6%), and above 3 cm (14%).

CONCLUSIONS

RP was an uncommon complication, both with local and local-regional RT. The addition of regional lymph node irradiation slightly increased the incidence of RP among patients treated with the partly wide tangential field technique. Concern for RP should, however, not deter patients with node-positive breast cancer from receiving local-regional RT.

Electron arc irradiation of the postmastectomy chest wall with CT treatment planning: 20-year experience

PURPOSE

Since 1980, electron arc irradiation of the postmastectomy chest wall has been the preferred radiotherapy technique at the University of Utah for patients with advanced breast cancer. We report the results of this technique in 156 consecutive Stage IIA-IIIB patients treated from 1980 to 1998.

METHODS

CT treatment planning was used in all patients to identify chest wall thickness and internal mammary lymph node depth. Computerized dosimetry was used to deliver total doses of 50 Gy in 5-1/2 weeks to the chest wall and the internal mammary lymph nodes with electron arc therapy. Patients were assessed for local, regional, and distant control of disease and for survival. Univariate and multivariate proportional hazards were modeled using a hierarchical nonproportional semiparametric model testing the following prognostic factors: age, stage, tumor size, number of positive lymph nodes, estrogen receptor status, and dose. End points evaluated included disease-free survival, cause-specific survival, and overall survival.

RESULTS

Eighty-one percent of patients were at high risk for local-regional failure because of > T2 primary tumor or > 3 positive axillary lymph nodes. The median number of positive lymph nodes was 5, and the median tumor size was 3.5 cm. Actuarial 10-year local-regional control and overall survival were 95% and 52%, respectively. In multivariate analysis, the only factor prognostic for disease-free survival, cause-specific survival, and overall survival was the number of positive lymph nodes (p < 0.001). The 10-year rates of local-regional control for patients with 0, 1-3, 4-9, and > or = 10 involved lymph nodes were 100%, 98%, 93%, and 89%, respectively. The only rates of acute and chronic radiotherapy toxicity > or = 2 by RTOG/EORTC criteria were skin related and observed in 44% and 10% for acute and late reactions, respectively.

CONCLUSION

These data demonstrate excellent local-regional control rates with electron arc therapy of the postmastectomy chest wall in patients with advanced breast cancer. Our 20-year experience with electron arc radiotherapy has demonstrated the safety and efficacy of this technique. The advantage of this technique is that the internal mammary lymph node chain can be easily encompassed while the dose to heart and lung is minimized; it also obviates match lines in areas of high risk.

An unusually extensive case of Paget's disease of the nipple

An unusually extensive case of Paget's disease of the nipple is presented. The patient had concealed the disease for over 10 years and was reluctant to accept treatment. A response was achieved with Tamoxifen. An initial complete response was obtained with radiation therapy, using an electron arc. Several plaques of recurrent disease developed in areas treated with less than 50 Gy, which have been controlled with the addition of superficial X-ray therapy. She remains well and disease-free 9 months following completion of treatment.

Chest wall irradiation with MLC-shaped photon and electron fields

PURPOSE

To improve the treatment technique for chest wall irradiation, using the multileaf collimator (MLC) of the MM50 Racetrack Microtron to shape both photon and electron beams, and to check the dose delivery in the match-line region of these fields for the routine and improved technique.

METHODS AND MATERIALS

Using diode and film phantom measurements, the optimal number of photon beam segments and their positions relative to the electron beam were determined. On phantoms, and during actual patient treatment using in vivo dosimetry, the dose homogeneity in the match-line region was determined for both the routine and improved techniques.

RESULTS

Three photon beam segments (9-mm gap, perfect match, and 9-mm overlap) were used to match the electron beam, resulting in minimum-maximum dose values in the match-line region of 88-109%, compared to 80-115% for the routine technique (2 photon beam segments). During patient treatment, the average minimum and maximum dose values were 95% and 115%, respectively, compared to 78% and 127%, respectively, for the routine technique. The interfraction variation in dose delivery was reduced from 11.0% (1 SD) to 4.6% (1 SD). The actual treatment time was reduced from 10 to 4.5 min.

CONCLUSION

Using the MLC of the MM50 to shape both photon and electron beams, an improved treatment technique for chest wall irradiation was developed, which is less labor intensive, faster, and yields a more homogeneous, and better reproducible dose delivery.

Radiotherapy of the chest wall following mastectomy for early-stage breast cancer: impact on local recurrence and overall survival

INTRODUCTION

Recent studies have renewed an old controversy about the efficacy of adjuvant radiotherapy following mastectomy for breast cancer. Radiotherapy is usually recommended for advanced disease, but whether or not to use it in pT1-T2 pN0 situations is still being debated. This study was designed to clarify whether or not routine radiotherapy of the chest wall following mastectomy reduces the risk of local recurrence and if it influences the overall survival rate.

METHODS

Retrospective analysis of patients treated with mastectomy for pT1-T2 pN0 tumors and no systemic treatment. Patients treated with radiotherapy of the chest wall following mastectomy (Group A) are compared with those treated with mastectomy alone (Group B).

RESULTS

A total of 918 patients underwent mastectomy. Patients who received adjuvant radiotherapy after mastectomy (n = 114) had a significantly lower risk for local recurrence. Ten years after the primary diagnosis, 98.1% of the patients with radiotherapy were disease free compared to 86.4% of the patients without radiotherapy. The average time interval from primary diagnosis until local recurrence was 8.9 years in Group A and 2.8 years in Group B. The Cox regression analysis including radiotherapy, tumor size and tumor grading found the highest risk for local recurrence for patients without radiotherapy (p < 0.0004). In terms of overall survival however, the Kaplan-Meier analysis showed no difference between the two groups (p = 0.8787) and the Cox regression analysis failed to show any impact on overall survival.

CONCLUSION

With observation spanning over 35 years, this study shows that adjuvant radiotherapy of the chest wall following mastectomy reduces the risk for local recurrence in node-negative patients with pT1-T2 tumors but has no impact on the overall survival rate.

Evaluation of predictive factors for local tumour control after electron-beam-rotation irradiation of the chest wall in locally advanced breast cancer

BACKGROUND AND PURPOSE

Different radiotherapy techniques are being used for chest wall irradiation after mastectomy. We review our results with the electron-beam-rotation technique in a series of 130 high risk breast cancer patients. The main end point of the study was local tumour control; secondary end points were disease free survival, and overall survival, as well as acute and late side effects.

MATERIAL AND METHODS

From January 1990 to June 1995, 89 patients underwent electron-beam-rotation irradiation of the chest wall after primary mastectomy and axillary lymph node dissection (group I) and 41 patients after excision of local recurrent breast cancer (group II) with 4 x 2.5 Gy/week to 50 Gy total dose (4-12 MeV electrons depending on the thickness of the chest wall). In addition, irradiation of local-regional lymph nodes and/or a local boost of 10 Gy were applied dependent on the resection and node status.

RESULTS

After a median follow up of 29 months (65% stadium III/IV) the 3 year local tumour control, disease free survival, and overall survival were 73%, 47%, and 75%, respectively. Local control in group I was 78% versus 60% in group II. Significant predictors for local tumour control, disease free survival, and overall survival were resection status (R0 versus R1/2) and estrogen receptor status (positive versus negative). In group I, tumour grading (GI-IIa versus GIIb-III) and estrogen receptor status were found to be additional significant prognostic factors for complete resected tumours. Five patients developed symptomatic pneumonitis (< 4%) and one patient developed a chronic fistula at the resection. A significant correlation between the degree of acute skin reaction and persistent pigmentation was observed.

CONCLUSION

In high risk breast cancer patients postoperative irradiation with the electron-beam-rotation technique of the chest wall is an effective therapy resulting in 78% local tumour control at 3 years for locally advanced breast cancer and 60% for recurrent disease. The rate of acute and late toxicity is low. The degree of acute skin reaction correlates with the degree of persistent pigmentation.

Response to radiation therapy and prognosis in breast cancer patients with BRCA1 and BRCA2 mutations

BACKGROUND AND PURPOSE

The purpose of this study is to evaluate overall survival in BRCA1 or BRCA2 breast cancer patients, describe presenting stage, review histologic findings and evaluate response to radiotherapy.

MATERIALS AND METHODS

A retrospective study was performed evaluating breast cancer patients with known mutations of BRCA1 or BRCA2. Patients from 12 different pedigrees were cross-referenced with the Utah Cancer Registry (UCR), histologic findings were verified and radiotherapy records were reviewed for acute response to treatment. Actuarial survival calculations were performed and patients were matched for age, date of diagnosis and tumor size.

RESULTS

Thirty breast cancer patients with BRCA1 mutations were found to have 34 breast cancers (four had bilateral metachronous lesions) and 20 breast cancer patients with BRCA2 mutations were found to have 22 breast cancers (two had bilateral metachronous disease). The median age at diagnosis was 49 years (range 21-77 years) and 42 years (range 23-83 years), respectively, for BRCA1 and BRCA2 patients. Unusual histologic types of breast cancers were represented with 7% (4/56) medullary and 5% (3/56) lobular carcinomas. Complete staging was possible for 63% (35/56) of cancers. Stages I, II, III and IV represented 26, 63, 6 and 6% of cancers, respectively. The most severe radiation reaction was moist desquamation which was self-limiting and developed in 29% (6/21) of irradiated patients. The mean follow-up was 9.8 and 7.5 years for BRCA1 and BRCA2 cancers, respectively. Kaplan-Meier survival analysis demonstrated 5-year survival values of 75% for BRCA1 patients, 73% for BRCA2 patients, 70% for matched controls and 69% for UCR controls. No statistically significant differences were evident between the groups at 5 or 10 years.

CONCLUSIONS

Despite their younger age at presentation, breast cancer patients harboring BRCAI or BRCA2 mutations present at a similar stage, display a normal acute reaction to radiotherapy and have a similar prognosis when compared with sporadic breast cancer patients.