Microwave ablation (MWA) is a newly developed minimally invasive tumor therapy which possesses several advantages over the existing thermal therapies. Despite the several advantages, MWA also suffers same disadvantages similar to other thermal therapies like poor control over ablation volume. Sensitivity of different tissue parameters is the key factor to design a MWA protocol. In this work, sensitivity analysis has been conducted to quantify the effect of three cancerous breast parameters, viz., breast composition, tumor location, and tumor size, on the efficacy of MWA of breast cancer. Ablation volume has been taken as the indicator of the ablation efficacy during MWA procedure. A Taguchi's design of experimental approach has been utilized to optimize the number of simulations required for the analysis and then analysis of variance (ANOVA) has been performed to predict the most sensitive parameter along with their individual contribution. Finite element approach-based simulations have been performed in a multiphysics software. First, a grid-independent study has been established to optimize the number of mesh elements and to reduce the computational cost. Then, after finding the most optimum grid size, all the simulations have been performed in accordance with the protocol obtained from Taguchi's design of experiment approach and finally statistical analysis software has been used for analyzing Taguchi's design. It has been found that, the breast composition to be the most significant factor, with maximum contribution in ablation volume, among three considered factors followed by tumor location and tumor size, respectively.