#1: Solid Tumor Rules (2018)
Source 1: 2018 Solid Tumor Rules
Source 2: CAP Protocol: Invasive Breast
Notes: Version: InvasiveBreast 18.104.22.168; Jan 2018
Solid Tumor Rules (2018)--Breast: How many primaries are accessioned when a prophylactic mastectomy reveals a final diagnosis of invasive tubular carcinoma, but the College of American Pathologists (CAP) Protocol includes ductal carcinoma in situ (DCIS) sized separately and it is not clear if these are different tumors? See Discussion.
The patient was incidentally diagnosed with cancer on a prophylactic mastectomy, so there are no positive imaging findings to correlate the number of tumors/masses. The final diagnosis was invasive tubular carcinoma, and referred to the CAP Protocol. The CAP notes:
Focality of invasive carcinoma: Single contiguous focus. However, it does not specify whether the single contiguous focus also includes the in situ component. The CAP goes on to note DCIS was present:
Distance spanned by DCIS: 2.2 cm; DCIS qualifies as The gross description does not provide any indication of either a single or multiple tumors/masses/lesions, though it was referred to as “Lesion 1" in the gross description with no indication of other lesions.
extensive intraductal component: No.
The format of the CAP Protocol frequently does not specify whether the DCIS is a separate measured tumor, or if it is a component of the invasive tumor. This makes it difficult to determine whether the DCIS should be a separate primary when the invasive tumor is not also a type of ductal carcinoma. Per both the 2007 MP/H and 2018 Solid Tumor Rules, an invasive tubular carcinoma and a ductal carcinoma in situ would be multiple primaries if they were multiple tumors. Should we default to Rule M1: Abstract a single primary when it is not possible to determine if there is a single or multiple tumors? Or should we assume these are separate tumors because they were both sized, the focality only described a single invasive tumor, and the tumors are not both ductal carcinomas?
Accession a single primary using Solid Tumor Rule M3. Based on the information provided, this was described as ‘Lesion 1’ with no other lesions noted in the gross description. If the DCIS was a separate tumor, this would have been noted by the pathologist.
Reminder, the breast CAP protocol is a checklist for pathologists to note their findings while reviewing the slides and/or specimen. The findings and notes should be consolidated into a final/synoptic report.