Breast ductal carcinoma in situ with microinvasion: a definition supported by a long-term study of 1248 serially sectioned ductal carcinomas.
BACKGROUND
The significance of microinvasion is still debated and clinical management is controversial. The authors defined ductal carcinoma in situ with microinvasion (DCIS-MI) as DCIS with infiltration of the periductal stroma by a few tumor cells, singly (type 1) or in clusters (type 2). With this definition, the authors attempted to evaluate the clinical significance of microinvasion.


METHODS
The authors compared the clinical, pathologic features, and survival (median follow-up, 7.3 years) of 1248 patients with, respectively, DCIS (722 patients), DCIS-MI with microinvasion type 1 and type 2 (243 patients), and invasive ductal carcinoma in situ with a predominant DCIS component greater than or equal to 80% of the tumor (IDC-DCIS, 283 patients).


RESULTS
Microinvasion was associated with DCIS histologic type, grade, and extent (respectively, P < 10(-8), P < 10(-3), P < 10(-4)). Axillary lymph node metastases were observed in a few patients with DCIS and DCIS-MI type 1 (respectively, 1.4% and none), in 10.1% with DCIS-MI type 2 and in 27.6% with IDC-DCIS. Metastasis free and overall survival probabilities were significantly different between three groups in the following order from best to worst prognosis: 1) the group comprising DCIS and DCIS-MI type 1, 2) the DCIS-MI type 2 group, and 3) the IDC-DCIS group.


CONCLUSIONS
The authors' results suggest there are two types of DCIS-MI: 1) type 1 that behaves like DCIS and should be managed as such; 2) type 2 that is less pejorative than IDC-DCIS but is more so than type 1.
de Mascarel
Isabelle
I
Department of Pathology, Institut Bergonié, Regional Cancer Center, Bordeaux, France. mascarel@bergonie.org
MacGrogan
Gaëtan
G
Mathoulin-Pélissier
Simone
S
Soubeyran
Isabelle
I
Picot
Véronique
V
Coindre
Jean-Michel
JM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001706:Biopsy; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D002278:Carcinoma in Situ / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000473:pathology* / Q000601:surgery / Q000628:therapy; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008867:Microtomy; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011379:Prognosis; D011878:Radiotherapy; D015996:Survival Rate