1-9-2026
Scenario:
- 1-9-2024 R Breast Invasive Ductal Carcinoma, treated w/ Lumpectomy, Radiation, Hormone, at last Follow up Patient NED
- 1-9-2026 R Breast bx+ Invasive Lobular carcinoma
Question: Is this a multiple primary or single primary?
- Multiple
- Single
Answer: Multiple
Solid Tumor Rules Update 2026
Rule M13 Abstract multiple primaries when separate/non-contiguous tumors are:
• On different rows in Table 3 in the Site-group Instructions
Note 1: Timing is irrelevant. Tumors may be synchronous or non-synchronous.
2026 Solid Tumor Rules Revisions–Breast- M Rule deleted: “Abstract a single primary when there are multiple tumors of carcinoma NST/duct and lobular.” Remaining rules re-numbered.
