#1: MP/H Rules
Source 1: 2016 SEER Manual
Source 2: SINQ 20110111
MP/H Rules/Behavior--Breast: How many primaries are to be abstracted for a patient with a history of left breast ductal carcinoma in situ (DCIS) diagnosed in 2014 and bone lesions showing metastatic carcinoma consistent with a breast primary in 2017? See Discussion.
Patient was diagnosed with DCIS of the left breast in June 2014. The patient had a simple mastectomy with 2 axillary lymph nodes removed. The final diagnosis was intermediate to high grade ductal carcinoma in situ, predominantly micropapillary type, forming a 1.4 cm mass. No invasive carcinoma identified. Margins negative. In April 2017, the patient was found to have parietoccipital bone lesions, which were resected. The resulting diagnosis was metastatic carcinoma, morphologically consistent with breast primary – See Comment: The previous breast lesion is not available for review at the time of signout. However, the tumor is morphologically compatible with a breast primary.
SINQ 20110111 would not make this is new primary. However, it seems that rule M8 might apply. An invasive tumor following an in situ tumor more than 60 days after diagnosis is a multiple primary. See Note 2: Abstract as multiple primaries even if the medical record/physician states it is recurrence or progression of disease.
Assuming there were no other breast or any other tumors for this patient, change the behavior code to /3 on the original abstract for the 2014 breast primary.
Similar to SINQ 20110111, there was likely a focus of invasion present in the original tumor that was not identified by the pathologist. The behavior code on the original abstract must be changed from a /2 to a /3 and the stage must be changed from in situ to localized.
The MP/H rules do not apply to metastases. Therefore, rule M8 cannot be used.