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SEER Inquiry System - Report
Produced: 10/23/2025 11:51 AM
Question 20091128
Inquiry Details
References:
2007 SEER Manual, 7
Question:
MP/H Rules/Multiple primaries--Breast: How many primaries are to be accessioned when a patient was diagnosed with breast carcinoma in 2001 and was subsequently diagnosed with a mammary carcinoma in a chest wall mass in 2008? See Discussion.
Discussion:
Patient was diagnosed with invasive lobular carcinoma of the right breast in April 2001. Following modified radical mastectomy in May 2001, the patient was disease free. In December 2008 the patient was diagnosed with a right chest wall mass, invasive poorly differentiated mammary carcinoma with lobular origin. If this is a new primary in 2008, would we code the primary site to breast or chest wall? Please see I&R answers 25924, 22163 and 26155 with similar case scenarios that give two different answers. One response indicates coding this type of scenario as new primary to chest wall and the other two responses indicate this should not be a new primary because the chest wall is a metastatic site. The pathology report does not state that this is metastatic and it is unknown if there is breast tissue left behind at the chest wall.
Answer:
For cases diagnosed 2007 or later, this case is a single primary. The chest wall (NOS) is a metastatic site for breast cancer. There is no mention of residual breast tissue, so the 2008 diagnosis cannot be a new primary.
"Chest wall" is an ambiguous term. It can mean the internal chest wall or the external chest wall. When the path report states that the "recurrence" is in residual breast tissue, this is most likely the external chest wall and the residual breast tissue is part of the breast not removed by the MRM. In contrast, skin or the chest wall, NOS, are regional metastases.
