Abstract Background Breast cancer is one of the most frequently diagnosed cancers worldwide and is a major contributor to cancer mortality in women. Breast cancer is treated with a multidisciplinary approach involving surgical oncology, radiation oncology, and medical oncology, which has been associated with a reduction in breast cancer. Aim of the Work The aim is to compare the outcome of Ain Shams university hospitals patients treated by mastectomy and BCS. The comparison takes the available prognostic variables into a multivariate analysis and includes an intention to treat analysis. Patients and Methods We randomized 20 patients in a retrospective cohort study who received either modified radical mastectomy or breast conserving surgery in period 2019-2020. We compared the outcome of patients after 1-2 year as regard post-operative hospital stay, time of Redivac drain removal, development of post-operative seroma, wound infection, wound hematoma, wound dehiscence, development of ugly scar with evaluation of recurrence be clinical examination and ultrasound follow up and take in consideration the type of adjuvant therapy that has been taken. Results We found that there's no significance between Modified radical mastectomy and conservative breast surgery according to recurrence, post-operative adjuvant therapy and hospital stay with small significance according to post-operative wound healing, seroma, hematoma, infection, wound dehiscence with better outcome to the conservative breast surgery. We found also high significance between the two invasive procedures according to the patient satisfaction with high satisfaction to the conservative breast surgery mostly due to the preservation of the breast and less wound complications Conclusion Both Breast cancer invasive procedures as regard mastectomy and conservative breast surgery have the same results according to recurrence, hospital stay and adjuvant therapy. Conservative breast surgery is better than mastectomy when indicated as regard wound complications and preservation of the breast tissue which increase patient satisfaction towards it.