The Evolving Role of Postmastectomy Radiation Therapy

A systematic review and meta-analysis of postmastectomy radiation therapy on prepectoral versus subpectoral breast reconstruction

Background

Prepectoral breast reconstruction has once again appealed, which attributes to the introduction of acellular dermal matrices (ADMs) and mesh. Postmastectomy radiation therapy (PMRT), meanwhile, is crucial in the whole course of treatment for breast cancer patients with lymph node-positive. The impact of PMRT on outcomes after prepectoral breast reconstruction has not been clearly defined to date. This study aimed to compare the impact of PMRT on outcomes after prepectoral vs. subpectoral breast reconstruction.

Methods

A comprehensive research on databases including PubMed, Embase, and Cochrane libraries was performed to retrieve literature pertaining to prepectoral breast reconstruction from database inception to October 2021. All included studies evaluated the impact of PMRT on outcomes after breast reconstruction. Only studies comparing patients who underwent prepectoral breast reconstruction with a control group who underwent subpectoral breast reconstruction were included. Data were analyzed using RevMan version 5.2.

Results

A total of 4 studies were included in the meta-analysis, with a total of 394 breasts. In the setting of postmastectomy radiation therapy, 164 breasts were reconstructed with a prepectoral approach, whereas the remaining 230 breasts underwent subpectoral reconstruction. Overall, outcomes between PBR and SBR was no statistical significance in the overall complications (OR: 1.30, 95% CI: 0.35-4.85), infection (OR: 1.62, 95% CI: 0.90-2.91), seroma (OR: 1.60, 95% CI: 0.48-5.27), skin flap necrosis (OR: 0.77, 95% CI: 0.17-3.45), hematoma (OR: 0.38, 95% CI: 0.10-1.41), wound dehiscence (OR: 0.82, 95% CI: 0.36-1.85). But, included studies lacked data about the patient quality of life and satisfaction with the outcome of the reconstructed breast.

Conclusions

In the setting of postmastectomy radiation therapy, prepectoral breast reconstruction is a safe and effective option.

Implicaciones de la pandemia en la radioterapia para el cáncer de mama. Omisión de la radioterapia

La pandemia actual por el nuevo coronavirus (SARS-CoV-2) exige que los sistemas de salud rápidamente adopten medidas encaminadas a mitigar la crisis, lo que implica redistribuir los recursos económicos, sociales y la fuerza laboral, para que aquellos sectores de la población más afectados puedan ser atendidos de forma óptima y oportuna. En los pacientes con carcinoma mamario in situ e invasivo de bajo riesgo, la radioterapia postoperatoria no ofrece ningún beneficio en supervivencia global, lo que hace atractiva la idea de omitir este recurso oncológico. En este artículo, se realizó una revisión de la literatura sobre los criterios para omitir la radioterapia adyuvante en los pacientes con neoplasias mamarias de bajo riesgo. Adicionalmente, se resumen las recomendaciones emitidas por algunas sociedades científicas internacionales durante la contingencia actual, y se analizan determinadas razones por las cuales los médicos se rehúsan a cambiar conductas clínicas que ofrecen ventajas limitadas, muchas veces contrarrestadas por los riesgos y los efectos adversos asociados.

The impact of variable relative biological effectiveness in proton therapy for left-sided breast cancer when estimating normal tissue complications in the heart and lung

The aim of this study was to evaluate the clinical impact of relative biological effectiveness (RBE) variations in proton beam scanning treatment (PBS) for left-sided breast cancer versus the assumption of a fixed RBE of 1.1, particularly in the context of comparisons with photon-based three-dimensional conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT). Ten patients receiving radiation treatment to the whole breast/chest wall and regional lymph nodes were selected for each modality. For PBS, the dose distributions were re-calculated with both a fixed RBE and a variable RBE using an empirical RBE model. Dosimetric indices based on dose-volume histogram analysis were calculated for the entire heart wall, left anterior descending artery (LAD) and left lung. Furthermore, normal tissue toxicity probabilities for different endpoints were evaluated. The results show that applying a variable RBE significantly increases the RBE-weighted dose and consequently the calculated dosimetric indices increases for all organs compared to a fixed RBE. The mean dose to the heart and the maximum dose to the LAD and the left lung are significantly lower for PBS assuming a fixed RBE compared to 3DCRT. However, no statistically significant difference is seen when a variable RBE is applied. For a fixed RBE, lung toxicities are significantly lower compared to 3DCRT but when applying a variable RBE, no statistically significant differences are noted. A disadvantage is seen for VMAT over both PBS and 3DCRT. One-to-one plan comparison on 8 patients between PBS and 3DCRT shows similar results. We conclude that dosimetric analysis for all organs and toxicity estimation for the left lung might be underestimated when applying a fixed RBE for protons. Potential RBE variations should therefore be considered as uncertainty bands in outcome analysis.