This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Surgery
[{'content': 'Which of the following pathologic findings is/are the strongest contraindication to breast preservation (lumpectomy with breast radiation) as primary treatment for a newly diagnosed breast cancer? \nSelect and explain. \nA. Grade 3, poorly differentiated, infiltrating ductal carcinoma, B. Extensive intraductal cancer around the invasive lesion, C. Tumor size less than 3 cm, D. Positive surgical margin for invasive cancer', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The only firm contraindication to wide excision and radiation (breast preservation, lumpectomy) as the primary surgical treatment for a newly discovered breast cancer is the inability to achieve an uninvolved surgical margin after excision of the tumor. A positive surgical margin requires, at least, reoperation with an attempt at re-excision of cancer. If the margin of removal is positive after attempts at re-excision, this is a strong reason to recommend mastectomy in preference to breast conservation. Tumor size is a relative contraindication when the cancer is so large in relation to the breast that excision to a clean surgical margin seems unreasonable. Other histologic findings, such as tumor grade or vascular invasion, are not strong reasons to recommend a mastectomy if the patient would prefer breast conservation.', 'role': 'assistant'}]