Stage IIB Breast Cancer

This is an international, multi-center, randomised, open label, superiority phase III trial of elacestrant vs standard endocrine therapy in patients with ER+/HER2- breast cancer and ctDNA relapse. During the ctDNA screening phase, patients will be tested at different timepoints to detect the presence of ctDNA in their blood. Patients who are found to be ctDNA-positive and have no evidence of distant metastasis, will be randomised 1:1 between standard endocrine treatment (the same they were receiving when tested ctDNA positive) versus elacestrant, provided they meet all eligibility criteria. After completion of the protocol treatment period, treatment will be left at the discretion of the treating physician.

This phase II trial investigates how well trastuzumab deruxtecan works alone or in combination with anastrozole in treating patients with HER2 low, hormone receptor positive breast cancer. Trastuzumab deruxtecan is a monoclonal antibody, called trastuzumab, linked to a chemotherapy drug called deruxtecan. Trastuzumab attaches to HER2 expressed at low levels on cancer cells in a targeted way and delivers deruxtecan to kill them. Anastrozole works by decreasing estrogen production and suppressing the growth of tumors that need estrogen to grow. This study is evaluating how effective trastuzumab deruxtecan is at treating hormone receptor positive cancer cells that have low levels of HER2 expressed on them when given alone or in combination with anastrozole.

This clinical research aims to determine if concurrent chemotherapy and radiation therapy is more effective than sequential chemotherapy and radiation therapy for patients with stage IIB-III breast cancer. It seeks to answer the following key questions: 1. When compared to sequential treatment, does concurrent chemoradiotherapy increase disease-free survival? 2. What effects does concurrent treatment have on post-operative look, quality of life, and side effects including arm swelling (lymphoedema)? 3. What are each treatment approach's financial costs? Researchers will compare the following to groups: Arm A: Participants in the sequential treatment group will first undergo chemotherapy and then radiation. and Arm B: Participants in the concurrent treatment group will undergo radiation therapy while undergoing chemotherapy. Participants are going to: 1. Get the usual chemotherapy (taxanes and/or anthracyclines). 2. Receive radiation therapy for three to four weeks. 3. Have follow-up visits every 6months for 5years to check for cancer recurrence, side effects, and quality of life.