Evaluation of acute skin toxicity in breast radiotherapy with a new quantitative approach.

BACKGROUND AND PURPOSE: Current criteria to evaluate acute radiodermatitis are highly subjective so quantification of physiological parameters is needed. We describe a non-invasive method of assessing skin microcirculation in breast cancer patients treated with hypofractionated radiotherapy and correlate them with the CTCAE scale. METHODS: Prospective study of 63 patients where blood flow was measured with real-time laser Doppler flowmetry (LDF) at baseline, weekly, and 3-months post-radiotherapy. Skin toxicity was assessed with the microcirculation index (MCI), a novel index based on blood flow parameters obtained via LDF. RESULTS: MCI was positively correlated (R=0.647; p<0.001) with the dose. Changes in MCI from baseline to the end of radiotherapy and at 3-months post-radiotherapy were significant (p<0.001). All CTCAE groups experienced a significant increase in MCI values from baseline to end of radiotherapy (p<0.001 for CTCAE grades 0 and 1; and p=0.028 for the grade 2 group). Significant differences in MCI values were observed among CTCAE groups at the end of radiotherapy (p=0.016). CONCLUSIONS: LDF is an accurate and objective measure of changes in blood flow. The comparison with the CTCAE shows the limitations of this subjective way of classifying patients. LDF is the first step for future studies of radiodermatitis treatments and prevention.

Tumor bed segmentation: first step for partial breast irradiation.

INTRODUCTION: In breast IMRT simultaneous integrated boost (SIB) treatment and accelerated partial breast irradiation (APBI), proper delineation of the tumor bed is necessary. Conservative oncoplastic surgery causes changes in peritumoral breast tissue that complicates locating the site of the tumor. Nevertheless, there are still centers that do not use surgical clips to delineate the site. This study aims to show how the lack of clips affects the techniques of SIB and APBI in terms of dose distribution and safety margins in the tumor bed. MATERIALS AND METHODS: On 30 patients, the defining of the tumor bed obtained from the pre-surgery CT scan to that outlined on the basis of clips on the post-surgery CT was compared. Tumor bed deviation from the original tumor site was quantified. In addition, the margins to the original tumor site necessary to guarantee the coverage of the tumor bed were calculated. RESULTS: Variations were detected in the distances between geometric centers of the PTV (minimum 0.5-maximum 3 cm). The maximum margin necessary to include the entire tumor bed was 4.5 cm. Lesions located in the upper outer quadrant required the widest margins. If margins are not added, the tumor bed volume defined with clips will be underdosed. CONCLUSIONS: The definition of the tumor bed based on studies before surgery does not have the necessary accuracy. Clips need to be placed in the surgical bed to identify the changes occurring after the restorative mammoplasty. Without clips, SIB and APBI are not safe.

Asociación entre la incidencia de alteraciones tomográficas pulmonares y el volumen pulmonar irradiado en pacientes con cáncer de mama / Relation between incidence of tomographic changes and radiated volume in the lungs of breast cancer patients

Objetivo: Determinar mediante tomografía pulmonar de alta resolución, la incidencia de alteraciones producidas por la irradiación del cáncer de mama en el pulmón y su relación con el volumen pulmonar irradiado. Material y métodos: Estudio prospectivo de 59 pacientes con cáncer de mama sometidas a radioterapia complementaria. Se practicó tomografía pulmonar de alta resolución a los tres y nueve meses de finalizar la radioterapia. Se analizó la incidencia de signos de neumonitis y fibrosis por radiación, y se estudió su relación con el volumen pulmonar irradiado. Resultados: El desarrollo del signo más frecuente de neumonitis (consolidaciones parcheadas contenidas en el pulmón irradiado pero no limitadas a la forma del campo de radiación) y de los más frecuentes de fibrosis (pérdida de volumen y desarrollo de opacidades lineales abigarradas), se asociaron significativamente al volumen y porcentaje de pulmón incluido en el campo de tratamiento, de forma que en las pacientes que no los presentaron, el porcentaje y el volumen pulmonar irradiado fueron muy inferiores al de las pacientes que sí los desarrollaron. La edad y la quimioterapia no se asociaron significativamente a la presencia de los signos de neumonitis y fibrosis por radiación. Todas las pacientes permanecieron asintomáticas. Conclusiones: Es necesario realizar una minuciosa simulación de los tratamientos y cuantificar en cada paciente el volumen pulmonar incluido en el campo de irradiación, y es recomendable llevar a cabo un seguimiento de la función pulmonar de aquellas pacientes en las que no sea factible la irradiación de un volumen de pulmón inferior a 150 cm3 o un porcentaje del volumen pulmonar inferior al 12 por ciento (AU)