Correlations between patient-specific parameters and dosimetric indices for personalized breast cancer radiotherapy.

Treatment planning parameters in radiotherapy are key elements that dictate the success of treatment outcome. While some parameters are commonly evaluated irrespective of cancer type, others are site-dependent and strongly patient specific. Given the critical influence of planning parameters on personalized therapy, the aim of this study was to evaluate the correlations between the dosimetric indices (conformity, homogeneity and mismatch indices) related to tumor coverage and the patient-specific parameters which encompass parameters pertaining to organs at risk (widths and lengths of heart and ipsilateral lung included in treatment fields, mean/maximum doses to heart, ipsilateral lung, left anterior descending aorta and contralateral breast) and tumor volume. Forty breast cancer patients were divided into two groups according to tumor location: twenty with left-sided (group A) and twenty with right-sided breast cancer (group B). Conformal (3DCRT), intensity modulated (IMRT) and volumetric arc modulated (VMAT) radiotherapy techniques were used for plan creation. Moderate to strong correlations were found for ipsilateral lung parameters for both groups of patients regardless of the treatment technique. Moderate to strong correlations were found for heart parameters in group A patients, while no correlations were observed in group B. The mismatch index presented moderate to strong correlations with tumor volume for all treatment techniques (r = -0.861 3DCRT, r = -0.556 IMRT, r = -0.533 VMAT) particularly in group A. The evaluated correlations indicate the role of dosimetric indices in personalized treatment planning.