This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oncology, Subject name: Medicine
A 53-year-old woman presents with a 1-cm invasive carcinoma of the breast, detected on mammography. She feels well and has no other symptoms. On examination the lump is palpable, and there are no axillary lymph nodes. Which of the following is the most appropriate local therapy for her tumor? 
Select and explain. 
A. simple mastectomy with axillary dissection, B. radiation therapy to breast and axilla, C. local excision plus radiation therapy, D. local excision and axillary dissection followed by radiation therapy
D: local excision and axillary dissection followed by radiation therapy
Answer: D: local excision and axillary dissection followed by radiation therapy 
Explanation: Breast-conserving surgery is now recommended for small tumors. Radiation therapy will decrease local recurrence rates. For tumors < 1 cm, adjuvant therapy is indicated only if axillary nodes are positive. Therefore, in this case, an axillary dissection will provide important therapeutic information. However, this is an area of rapidly changing knowledge and practice.