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SEER Inquiry System - Report
Produced: 05/21/2026 4:12 AM
Question 20100093
Inquiry Details
References:
2010 SEER Manual. Appendix C
Question:
MP/H Rules/Multiple primaries: Please clarify how rule M10 for Other Sites was developed and how a "recurrence" of the tumor after one year was determined to be a new primary? See Discussion.
Discussion:
What is the expected outcome or result of rule M10? Specifically, for soft tissue sarcomas, why is a recurrence after one year a new primary instead of a recurrence?
Answer:
For cases diagnosed 2007 or later: Rule M10, tumors occurring more than one year apart are multiple primaries, was developed to differentiate a new primary from a recurrence. The rule was developed with the concurrence of the CoC site-specialty physicians and the SEER consulting pathologist. There was agreement between all of the CoC site teams and the consulting pathologist that statements of recurrence should not be relied upon to rule out a new primary. The time limits for each site were set based on information from peer-reviewed articles on tumors occurring in the same site and studies using molecular studies to confirm whether or not the tumors were histologically similar. Determination of the time limit for the "other sites" rules was probably the most difficult because so many sites are involved. However, the specialty-physicians felt that one year was an appropriate length of time to apply to these sites.
