What is the preferred dye, patent blue or methylene blue (MB), for sentinel lymph node biopsy (SLNB) in breast cancer?

Patent Blue vs Methylene Blue for Sentinel Lymph Node Biopsy in Breast Cancer

Patent Blue V is the preferred dye for sentinel lymph node biopsy (SLNB) in breast cancer when combined with radioisotope, offering superior identification rates and established safety profile compared to methylene blue. 1, 2

Comparison of Dyes for SLNB

Patent Blue V

• Standard dye used in Europe and UK for SLNB in breast cancer 1
• High identification rate when combined with radioisotope (98.8%) 3
• Comes in 2-ml vials at 2.5% concentration 1
• Rare anaphylactic reactions (1-3%) 4
• Temporary skin tattooing reported in 3.8% of patients 3

Methylene Blue

• Alternative dye with lower cost and wider availability 4
• Acceptable identification rate (97.6%) 4
• Higher rate of local inflammation (5 cases vs 1 case with Patent Blue) 5
• Lower rate of skin discoloration (14.1% vs 23.7% with Patent Blue) 5

Efficacy Comparison

The combined technique using radioisotope and blue dye provides the highest sentinel node identification rates:

• Combined technique (radioisotope + Patent Blue): 98.8% identification rate 3
• Radioisotope alone: 97.5% identification rate 3
• Blue dye alone: 92.5% identification rate 3

The National Comprehensive Cancer Network (NCCN) and American College of Radiology emphasize that the combination of radiocolloid and blue dye provides the highest SLN detection rate (97.7%) compared to either technique alone 2.

Safety Considerations

When choosing between dyes, consider these safety profiles:

• Patent Blue V: Rare anaphylactic reactions (1-3%), temporary skin tattooing 4
• Methylene Blue: Higher rate of local inflammation, lower rate of skin discoloration 5

Technical Aspects

For optimal SLNB technique:

• Inject dye at time of surgery under general anesthesia 1
• Allow 10-15 minutes for dye to travel from injection site to SLN 1
• Use proper search pattern (raster pattern of parallel lines 2cm apart) 2
• If SLN cannot be identified after 20 minutes, proceed with complete axillary lymph node dissection 2

Special Considerations

• Blue dye is contraindicated in children, pregnant women, lactating women, and those with history of allergy to blue dye 1
• Wear gloves to avoid staining and use gauze to prevent dye spillage 1
• Document techniques used, duration of search, and reasons for proceeding to ALND if SLN cannot be identified 2

Algorithm for Dye Selection

1. First choice: Combined technique with radioisotope and Patent Blue V
2. If Patent Blue V unavailable or contraindicated: Consider methylene blue as alternative
3. If patient has history of allergic reactions: Consider radioisotope alone (97.5% identification rate)
4. If neither dye nor radioisotope available: Proceed with traditional axillary lymph node dissection

The evidence strongly supports using the combined technique with radioisotope and Patent Blue V as the standard approach for SLNB in breast cancer, with methylene blue as a reasonable alternative when Patent Blue is unavailable or contraindicated.