Breast Cancer Staging
The clinical stage of breast cancer is determined primarily through physical examination of the skin, breast tissue, and lymph nodes (axillary, supraclavicular, and cervical). However, clinical determination of axillary lymph node metastases has an accuracy of roughly 33%. Mammography, chest x-ray, and intraoperative findings (primary cancer size, chest wall invasion) also provide necessary staging information. Pathologic stage combines clinical stage data with findings from pathologic examination of the resected primary breast cancer and axillary lymph nodes.
A frequently used staging system is the TNM (tumor, nodes, and metastasis) system. The American Joint Committee on Cancer (AJCC) has modified the TNM system for breast cancer. Tumor size correlates with the presence of axillary lymph node metastases, and there is an association between tumor size, axillary lymph node metastases, and disease-free survival. The single most important predictor of 10- and 20-year survival rates in breast cancer is the number of axillary lymph nodes involved with metastatic disease. Routine biopsy of internal mammary lymph nodes is not recommended even though the frequency of internal mammary lymph node metastases increases in proportion to the size of central and medial quadrant cancers. Clinical or pathologic evidence of metastatic spread to supraclavicular lymph nodes is indicative of systemic (stage IV) disease, but routine scalene or supraclavicular lymph node biopsy is not indicated.
Axillary lymph node groups. Level I includes lymph nodes located lateral to the pectoralis minor muscle (PM); level II includes lymph nodes located deep to the PM; and level III includes lymph nodes located medial to the PM. Arrows indicate the direction of lymph flow. The axillary vein with its major tributaries and the supraclavicular lymph node are also illustrated.
See short video on Breast Anatomy and Incisions from Zollinger's Atlas of Surgical Operations
Board Review Questions
1. Choose the one best response to this question.
Which of the following is true with respect to sentinel lymph node biopsy?
A. Localization of the sentinel node is successful in approximately 75% of cases.
B. Misses isolated micrometastases in nonsentinel nodes in 20% of cases.
C. It is unnecessary in patients with primary tumors less than 1 cm (T1a), as the rate of metastases is less than 1%.
D. The time from injection to accumulation of dye in the sentinel node is longer for the radioactive tracer than isosulfan (Lymphazurin) dye.
E. When properly performed should yield a single sentinel lymph node.
2. Choose the one best response to this question. A 40-year-old woman presents with a 2 cm mass in her right breast first detected by mammography (figure below). Radiographic core biopsy of the lesion is selected for diagnosis and reveals infiltrating ductal carcinoma. She has no palpable axillary lymph nodes.
A sentinel lymph node biopsy reveals metastatic carcinoma. There is no evidence of distant metastases on further investigation. Her stage by the American Joint Committee on Cancer (AJCC) TNM staging system is:
3. Axillary lymph nodes are classified according to the relationship with the
A. axillary vein
B. pectoralis major muscle
C. pectoralis minor muscle
D. latissimus dorsi muscle
E. serratus anterior muscle
The correct answers will be posted later this week.