Evaluation of ionizing radiation as a risk factor for the incidence of breast cancer: long-term analysis after the cesium-137 accident in Goiânia, Brazil. An ecological study

ABSTRACT BACKGROUND: The largest radiological accident to occur in any urban area happened in Goiânia, Brazil, in 1987. OBJECTIVE: To evaluate the association between breast cancer incidence and ionizing radiation levels. DESIGN AND SETTING: Ecological study among residents of the city of Goiânia, Brazil. METHODS: The central region of Goiânia, with seven major sources of contamination from cesium-137, was defined as the study area. The addresses of women diagnosed with breast cancer were identified between 2001 and 2010. The data were geographically referenced and, using census data, the annual averages of crude incidence rates were estimated. The existence of clusters of new cases was ascertained by means of the Moran index. Correlations of radiometric measurements with the incidence were assessed using unconditional linear regression. RESULTS: A total of 4,105 new cases were identified, of which 2,233 were in the study area, and of these, 1,286 (57.59%) were georeferenced. The gross rates of total and referenced cases were 102.91 and 71.86/100,000 women, respectively. These were close to the average for Brazilian state capitals, which is 79.37/100,000 women. The cluster analysis showed slight correlations in three small sets of census tracts, but these were far from the sources of contamination. The scatter plot of points and the R2 value close to zero indicated that there was no association between the variables. CONCLUSION: This study reinforces the hypothesis that the ionizing radiation levels to which women living in Goiânia are now exposed to are not associated with the onset of new cases of breast cancer.

Recommendations for hypofractionated whole-breast irradiation

SUMMARY This recommendation consensus for hypofractionated whole-breast radiotherapy (RT) was organized by the Brazilian Society of Radiotherapy (SBRT) considering the optimal scenario for indication and safety in the technology applied. All controversies and contraindication matters (hypofractionated RT in patients who underwent chemotherapy [CT], hypofractionated RT in lymphatic drainage, hypofractionated RT after mastectomy with or without immediate reconstruction, boost during surgery, hypofractionated RT in patients under 50 years old, hypofractionated RT in large breasts, hypofractionated RT in histology of carcinoma in situ [DCIS]) was discussed during a meeting in person, and a consensus was reached when there was an agreement of at least 75% among panel members. The grade for recommendation was also suggested according to the level of scientific evidence available, qualified as weak, medium, or strong. Thus, this consensus will aid Brazilian radiotherapy experts regarding indications and particularities of this technique as a viable and safe alternative for the national reality.

RESUMO Este consenso de recomendações para a radioterapia (RT) hipofracionada de toda a mama foi organizado pela Sociedade Brasileira de Radioterapia (SBRT) considerando o cenário ideal para indicação e segurança na tecnologia aplicada. Questões de controvérsias e contraindicações (RT hipofracionada em pacientes submetidas à quimioterapia [QT], RT hipofracionada nas drenagens linfáticas, RT hipofracionada após mastectomia com ou sem reconstrução imediata, a realização de reforço de dose em leito cirúrgico [ou boost], RT hipofracionada em pacientes com idade menor que 50 anos, RT hipofracionada em mamas volumosas, RT hipofracionada em histologia de carcinoma in situ [CDIS]) foram discutidas em encontro presencial, sendo o consenso atingido quando existisse concordância de pelo menos 75% dos panelistas. O grau de recomendação foi também sugerido de acordo com o nível de evidência científico disponível, qualificado entre fraco, médio ou forte. Assim, este consenso deverá servir para auxiliar os especialistas da radioterapia brasileira em relação às indicações e particularidades dessa técnica, como uma alternativa segura e viável para a realidade nacional.

Avaliação da influência da radioterapia nas reconstruções de mama com TRAM / Evaluation of the effects of radiotherapy on breast reconstruction with a transverse rectus abdominis myocutaneous flap

Introdução: A radiação influencia negativamente os resultados das reconstruções de mama que utilizam implantes. No entanto, os efeitos da radiação sobre as reconstruções de mama apenas com tecidos autólogos ainda não está clara. O objetivo do trabalho é avaliar as complicações pós-operatórias de pacientes submetidas à reconstrução de mama com retalho do músculo reto abdominal (TRAM) imediato e tardio e correlacionar estatisticamente essas complicações com a presença ou não da radioterapia (RT). Métodos: Levantamento retrospectivo de prontuários de pacientes submetidas à reconstrução mamária, das quais 126 pacientes realizaram reconstrução mamária com TRAM no período de 2004 a 2011. Foram analisadas a presença ou não de RT e as complicações pós-operatórias nas reconstruções imediatas e tardias. As pacientes foram divididas em 3 grupos: 1) sem RT (somente TRAM), 2) (TRAM→RT), 3) (RT→TRAM). Para cada grupo foi avaliada a presença e ausência de complicações menores e maiores e aplicados testes estatísticos. Resultados: Os grupos estudados foram considerados homogêneos quanto a idade e índice de massa corporal. Houve maior incidência de complicações maiores nos grupos com RT após o TRAM (29,6%) em relação aos demais grupos: sem RT (23,4%) e RT antes do TRAM (5,6%). Entretanto, a diferença entre os grupos não se mostra estatisticamente significativa. Para as Complicações Menores, também não há evidências de diferenças estatisticamente significativas entre os grupos. Conclusão: Nesse estudo a radioterapia adjuvante não se mostrou como fator potencializador de complicações nas pacientes submetidas à reconstrução imediata com TRAM pós-mastectomia.

Introduction: Radiation negatively influences the results of breast reconstruction using implants. However, the effects of radiation on breast reconstruction with autologous tissue is still unclear. The objective of this study was to evaluate the postoperative complications in patients who underwent immediate and late breast reconstruction with a transverse rectus abdominis myocutaneous (TRAM) flap and statistically correlate these complications with the use of radiotherapy (RT). Methods: A retrospective survey of the medical records of patients who underwent breast reconstruction was conducted. Of the patients, 126 underwent breast reconstruction with a TRAM flap between 2004 and 2011. The presence or absence of RT and postoperative complications in the immediate and late reconstructions was assessed. The patients were divided into 3 groups as follows: 1) without RT (TRAM alone group), 2) TRAM→RT group, and 3) RT→TRAM group. The patients in each group were evaluated for the presence and absence of minor and major complications, and results were statistically analyzed. Results: The groups were considered homogenous for age and body mass index. The incidence of major complications was higher in the groups with RT after TRAM (29.6%) than in the other groups, namely the groups without RT (23.4%) and with RT before TRAM flap reconstruction (5.6%). However, the differences among the groups were not statistically significant. No evidence of statistically significant differences in minor complications were found among the groups. Conclusion: In this study, adjuvant RT was not a potentiating factor of complications in the patients who underwent immediate reconstruction with a TRAM flap after mastectomy.

Impacto da radioterapia adjuvante no resultado cosmético da reconstrução mamária imediata com retalho TRAM / Impact of adjuvant radiotherapy on the cosmetic outcome of immediate breast reconstruction performed using a transverse rectus abdominis myocutaneous flap

INTRODUÇÃO: O efeito da radioterapia adjuvante após a reconstrução mamária com retalhos autólogos é controverso. O objetivo deste estudo é analisar se a radioterapia pós-operatória causa alterações volumétricas e cosméticas após a reconstrução mamária imediata com retalho do músculo reto abdominal (TRAM, do inglês transverse rectus abdominis myocutaneous). MÉTODO: No total, foram avaliadas 25 pacientes submetidas a reconstrução autóloga com retalho TRAM pediculado pós-mastectomia por câncer de mama e radioterapia adjuvante. Os resultados estéticos tardios foram coletados após o intervalo mínimo de 6 meses posteriormente ao esquema completo da radioterapia. RESULTADOS: A média de idade das pacientes foi de 42,2 anos, variando de 30 anos a 53 anos. Duas (8%) perdas completas do retalho ocorreram por necrose gordurosa maciça, duas (8%) pacientes evoluíram com contratura do retalho e perda volumétrica, e 52% das pacientes apresentaram alterações cutâneas. Entretanto, a maioria das pacientes (84%) não evoluiu com perda significativa do volume inicial do retalho ou com distorção do contorno e contração do retalho. CONCLUSÕES: O resultado cosmético após a reconstrução mamária imediata com retalho TRAM irradiado foi aceitável, comparativamente aos dados descritos na literatura. Esses achados indicam que os retalhos podem sofrer distorções de contorno pela contração, além de perda volumétrica significativa em pacientes candidatas à reconstrução com TRAM e necessidade de radioterapia adjuvante pós-mastectomia. Assim, as complicações tardias da irradiação pós-operatória devem ser consideradas nesse contexto.

BACKGROUND: The outcome of adjuvant radiotherapy performed after breast reconstruction using autologous flaps is controversial. In this study, we aimed to assess whether postoperative radiotherapy would induce volumetric and cosmetic changes after immediate breast reconstruction performed using a transverse rectus abdominis myocutaneous (TRAM) flap. METHODS: We evaluated 25 patients who were previously diagnosed with breast cancer and underwent post-mastectomy autologous reconstruction with a pedicled TRAM flap followed by adjuvant radiotherapy. Late aesthetic results were recorded starting 6 months after the completion of a full course of radiotherapy. RESULTS: The average patient age was 42.2 years (range, 30-53 years). Two (8%) complete flap losses occurred due to massive fat necrosis. Two (8%) patients exhibited flap contracture and volume loss, whereas skin changes were observed in 52% of patients. Most of the patients (84%), however, had no significant initial flap volume loss, contour distortion, or flap contraction . CONCLUSIONS: The cosmetic result obtained in the present study by immediate breast reconstruction performed using an irradiated TRAM flap was satisfactory compared to the data described in the literature. These findings suggest that the flap contours may be distorted by contraction and that significant volume losses can be observed in patients who may be candidates for TRAM flap reconstruction and require post-mastectomy adjuvant radiotherapy. Thus, in these circumstances, late complications due to postoperative irradiation should be considered.

Determinación de un método de cálculo de dosis glandular promedio en exámenes de mamografía convencional / Determination of a method for calculating mean glandular dose in conventional mammography exams

We present the application of a numerical model to estimate the mean glandular dose for mammography. A General Electric mammography system, tube voltaje of 20-35 kV with increments of 1 kV, tube current of 10-250 mAs, anode/filter combinations molybdenum/molybdenum was used. Over a period of two months, data from 162 scans with craniocaudal and mediolateral oblique projections in both breasts were recorded. The thickness of the compressed breast ranged from 2.5 to 6.5 cm. The mean glandular dose for each craniocaudal projection ranged from 0.4 to 0.7 mGy for a thickness of 2.5 cm and 1.9 to 2.8 mGy for a thickness of 6.5 cm. All average values of mean glandular dose estimated by cranio-caudal projection were found to be below the international reference dose value of 3 mGy recommended by the American College of Radiology.

Presentamos la aplicación de un modelo numérico para estimar la dosis glandular promedio en mamografía. Hemos utilizado un mamógrafo General Electric, tensión del tubo: 20-35 kV con incrementos de 1 kV; carga del tubo: 10-250 mAs; combinación ánodo-filtro de Molibdeno-Molibdeno. Durante dos meses datos de 162 exploraciones con proyecciones cráneo-caudal y medio lateral oblicua en ambas mamas. El espesor de mama comprimida se encuentra en el rango de 2,5 a 6,5 cm. Los rangos de dosis glandular promedio, por cada proyección cráneo-caudal, se encuentran de 0,4 a 0,7 mGy para un espesor de 2,5 cm y de 1,9 a 2,8 mGy para un espesor de 6,5 cm. Los valores medios de dosis glandular promedio estimados por proyección cráneo-caudal, en su totalidad resultan por debajo del valor de referencia dado por el Colegio Americano de Radiología (3 mGy).

Acquiring molecular interference functions of X-ray coherent scattering for breast tissues by combination of simulation and experimental methods

Recently, it has been indicated that X-ray coherent scatter from biological tissues can be used to access signature of tissue. Some scientists are interested in studying this effect to get early detection of breast cancer. Since experimental methods for optimization are time consuming and expensive, some scientists suggest using simulation. Monte Carlo [MC] codes are the best option for radiation simulation; however, one permanent defect with MC codes has been the lack of a sufficient physical model for coherent [Rayleigh] scattering, including molecular interference effects. It was decided to obtain molecular interference functions of coherent X-ray scattering for normal breast tissues by combination of modeling and experimental methods. A Monte Carlo simulation program was written to simulate the angular distribution of scattered photons for the normal breast tissue samples. Moreover, experimental diffraction patterns of these tissues were measured by means of energy dispersive X-ray diffraction [EDXRD] method. The simulation and experimental data were used to obtain a tabulation of molecular interference functions for breast tissues. With this study a tabulation of molecular interference functions for normal breast tissues was prepared to facilitate the simulation diffraction patterns of the tissues without any experimental. The method may lead to design new systems for early detection of breast cancer

Dosimetric study of inverse-planed intensity modulated, forward-planned intensity modulated and conventional tangential techniques in breast conserving radiotherapy.

OBJECTIVE: The authors present the result of a dosimetric comparison of inverse-planed intensity modulated, forward-planned intensity modulated, and conventional tangential technique in breast conserving radiotherapy. METHOD AND MATERIAL: The breasts (Right side: Left side = 1:1), heart, and lungs of 28 patients were contoured on all the computed tomography (CT)-slice. Three different treatment plans were created: (1) inverse IMRT (iIMRT), (2) forward IMRT (fIMRT), and (3) conventional tangential technique (CVT). The total prescribed dose for all plans was 50 Gy/25 fractions. All treatment plans were normalized at 95% of the prescribed dose covered the entire PTV and used inhomogeneity corrections. RESULTS: For the entire group, the mean breast volume was 517 cc. The V105% for iIMRT, fIMRT and conventional plans was 1.12%, 2.36% and 16.81%, which iIMRT better than fIMRT and CVT (p < 0.001) and fIMRT better than CVT (p < 0.05). The Dmax for the iIMRT plan received 105.03%, which was significantly less than those from the fIMRT(106.6%, p < 0.001) and the conventional (110.68%, p < 0.001) plan. The PTV coverage (V95-105%) for the iIMRT, fIMRTand conventional was 96%, 91% and 87%, which iIMRT better than fIMRT and CVT (p < 0.05) and fIMRT better than CVT (p < 0.05). The PTV CI for the iIMRT technique was 0.704, which was significantly more conformity than those from the fIMRT (0.639, p < 0.001) and the conventional (0.539, p < 0.001) techniques. The PTV CI of fIMRT is significantly better than CVT (p < 0.005). Mean ipsilateral lung dose was 642.7 cGy, 747.6 cGy and 882.25 cGy for iIMRT fIMRT and CVT respectively (p < 0.05) The V20Gy reduced from 14.87% for conventional plan to 12.82% for the fIMRT plan, while 0.88% was obtained for the iIMRT plan (P<0.05). The heart V30 Gy value was 3.124%, 4.65%, and 5.84% for iIMRT, fIMRT and conventional plans, respectively (p < 0.05). The mean dose of contralateral breast was 55.86 cGy, 60.33 cGy, 68.57 cGy for iIMRT, fIMRT and conventional plans, respectively (p < 0.05 both). The mean contralateral lung dose was 57.8 cGy, 43.87 cGy, and 32.28 cGy for iIMRT, fIMRT and conventional plans, respectively (p < 0.005 both). CONCLUSION: The iIMRT technique provides significantly improved PTV Dmax, PTV V105%, PTV V110%, target volume coverage, dose homogeneity and dose conformity throughout the target volume of breast and reduced doses to all critical structures, compared to the fIMRT and conventional techniques. In view of fIMRT technique, it significantly improved the dose distribution and reduced dose to OARs compared to conventional technique, although not better than iIMRT technique.

Radiation dose to contralateral breast during treatment of breast malignancy by radiotherapy.

AIMS: External beam radiotherapy is being used regularly to treat the breast malignancy postoperatively. The contribution of collimator leakage and scatter radiation dose to contralateral breast is of concern because of high radio sensitivity of breast tissue for carcinogenesis. This becomes more important when the treated cancer breast patient is younger than 45 years and therefore the contralateral breast must be treated as organ at risk. Quantification of contralateral dose during primary breast irradiation is helpful to estimate the risk of radiation induced secondary breast malignancy. MATERIALS AND METHODS: In present study contralateral breast dose was measured in 30 cancer breast patients undergoing external beam therapy by Co-60 teletherapy machine. Postoperative radiotherapy was delivered by medial and lateral tangential fields on alternate days in addition to supraclavicle field daily with 200 cGy/F to a total dose of 5000 cGy in 25 fractions. CaSO4: Dy thermoluminescence dosimeter discs were employed for these measurements. Three TLD discs were put on the surface of skin of contralateral breast, one at the level of nipple and two at 3 cms away from nipple on both side along the midline for each field. At the end treatment of each filed, TLD discs were removed and measured for dose after 24 h on Thelmador-6000 TLD reader. RESULTS: The dose at the contralateral breast nipple was to be 152.5 to 254.75 cGy for total primary breast dose of 5000 cGy in 25 equal fractions which amounted to 3.05-6.05% of total dose to diseased breast. Further it was observed that the maximum contribution of contralateral breast dose was due to medical tangential half blocked field. CONCLUSION: CaSO4; Dy thermoluminescence dosimetry is quite easy, accurate and convenient method to measure the contralateral breast dose.

[FORTRAN code for glandular dose calculation in mammography using Sobol-Wu parameters]

Accurate computation of the radiation dose to the breast is essential to mammography. Various the thicknesses of breast, the composition of the breast tissue and other variables affect the optimal breast dose. Furthermore, the glandular fraction, which refers to the composition of the breasts, as partitioned between radiation-sensitive glandular tissue and the adipose tissue, also has an effect on this calculation. Fatty or fibrous breasts would have a lower value for the glandular fraction than dense breasts. Breast tissue composed of half glandular and half adipose tissue would have a glandular fraction in between that of fatty and dense breasts. Therefore, the use of a computational code for average glandular dose calculation in mammography is a more effective means of estimating the dose of radiation, and is accurate and fast. In the present work, the Sobol-Wu beam quality parameters are used to write a FORTRAN code for glandular dose calculation in molybdenum anode-molybdenum filter [Mo-Mo], molybdenum anode-rhodium filter [Mo-Rh] and rhodium anode-rhodium filter [Rh-Rh] target-filter combinations in mammograms. The input parameters of code are: tube voltage in kV, half-value layer [HVL] of the incident x-ray spectrum in mm, breast thickness in cm [d], and glandular tissue fraction [g]. The average glandular dose [AGD] variation against the voltage of the mammogram X-ray tube for d = 4 cm, HVL = 0.34 mm Al and g=0.5 for the three filter-target combinations, as well as its variation against the glandular fraction of breast tissue for kV=25, HVL=0.34, and d=4 cm has been calculated. The results related to the average glandular absorbed dose variation against HVL for kV = 28, d=4 cm and g= 0.6 are also presented. The results of this code are in good agreement with those previously reported in the literature. The code developed in this study calculates the glandular dose quickly, and it is complete and accurate. Furthermore, it is user friendly and useful for dose optimizing in mammography imaging

Evaluation of radiation pneumonitis in breast cancer patients

This is a prospective study included 30 patients with primary breast cancer who had modified radical mastectomy and postoperative radiation therapy to peripheral lymphatics and chest wall that had ben evaluated/or radiation pneumonitis [RP]. The assessment was done using clinical, radiographic [CXR] scintigraphic and pulmonry function tests for both pre and post-irradiation evaluation, the incidence of [RP] was 3.3%. However, the incidence of asymptomatic lung damage was 16.6% as evidenced by CXR and 13.3% evidenced in ventillation/perfusion [V/O] defects, as for pulmonary function [PFT] tests there were global affection of ventilation and per fusion data which is more marked in patients with abnormal radiographs and pulmonary scintigraphy [V/Q] defects. Risk factors for developing [RP] as well as asymptomatic lung damage were central lung distance [CLD] more than 3 cm, a lung volume in tangential field of more than 20% and the use of concurrent RT with CT. Lung damage should be monitored not only with plain radiographs

Is there a role for axillary irradiation following adequate surgical evacuation in node positive breast cancer patients

A total of 461 node positive female breast cancer cases were studied following mastectomy and axillary evacuation of at least 10 nodes. None were given axillary irradiation irrespective of the number of metastatic nodes or the presence of extracapsular infiltration. At a medium follow up period of 345 months [range 24 to 48 months] axillary recurrence occurred in 10 cases, of these, 7 patients had combined axillary and chest wall recurrences. Correlation of axillary recurrence with pathological type and grade, menstrual status, age and type of adjuvant systemic therapy were not found to be statistically significant. Symptomatic arm edema occurred in 6 patients, all were associated with axillary recurrence. In conclusion, postoperative axillary irradiation with its attending morbidity can be safely omitted in breast cancer patients following adequate axillary lymph node dissection as it does not improved loco-regional control

Role of chest wall irradiation in T2 breast cancer cases following mastectomy

This prospective study included 204 breast cancer cases with PT2 primary tumors out of 802 breast cancer cases who attended at NEMROCK over 3-year period [1993-1995]. Patients with PT2 tumors did not receive chest wall irradiation after radical or modified radical mastectomy irrespective of any risk factor according to breast unit protocol adopted in NEMROCK. The overall recurrence rate was 10.29%, a multivariate analysis was done to identify the significant predictors influencing chest wall recurrence concluded that +ve axillary lymph nodes, high tumors grade and inner quadrant site in age <35 years are significant predictors of chest wall recurrence in patients with PT2 breast cancer cases that require postoperative chest wall irradiation according to this study

Experience with interstitial iridium-192 irradiation and electron beam therapy after conservative surgery for locally advanced breast carcinoma

Thirty-one patients with locally advanced breast cancer [stage IIIA and IIIB] received booster irradiation to a dose of 15-20 Gy by electron beam therapy [20 patients] or interstitial iridium-192 [11 patients] after conservative surgery [lumpectomy and axillary dissection] and external irradiation to the breast and nodal regions [45-50 Gy/5 weeks]. All patients were initially treated by 3 cycles of combination chemotherapy [FAC] and all patients had tumor size /

Radiation complications related to axillary irradiation for breast cancer

The records of 1428 patients with breast cancer between January 1985 and December 1991 were reviewed. All cases received radiotherapy including the axilla. Acute and chronic radiation complications related to axilla were scored. These complications were analyzed in relation to the surgical procedures done before radiotherapy, total dose of irradiation and the type of radiation beam used. It was found that moderate and severe erythema and moist desquamation [score 2 + 3] were significantly higher in patients treated with deep X-ray [DXR] [37% and 7%, respectively], compared to those treated with telecobalt therapy [26% and 3%, respectively]. There was no significant difference in acute reactions as related to type of surgery or to total radiation doses less than 40 Gy or more than 40 Gy. As regards, chronic radiation reactions, edema of upper limbs was significantly influenced by the different factors. Edema of upper limbs was significantly higher in patients who had radical mastectomy [39.7%], modified radical mastectomy [33.6%], simple mastectomy plus axillary sampling [23.4%] in patients who received more than 40 Gy [34.4%] and those treated with DXR [32.6%]