biostudies-literatureShaaban AMCancer Research UK2125-2132https://www.ebi.ac.uk/biostudies/studies/S-EPMC9726983biostudies-literatureUnknown127(12)<h4>Background</h4>The diagnosis, management and prognosis of microinvasive breast carcinoma remain controversial.<h4>Methods</h4>We analysed the outcomes of patients with DCIS with and without microinvasion diagnosed between 2003 and 2012 within the Sloane project.<h4>Results</h4>Microinvasion was recorded in 521 of 11,285 patients (4.6%), with considerable variation in reported incidence among screening units (0-25%). Microinvasion was associated with high-grade DCIS, larger DCIS size, comedo necrosis and solid, cribriform architecture (all P < 0.001). Microinvasion was more frequent in patients who underwent mastectomy compared with breast-conserving surgery (BCS) (6.9% vs 3.6%, P <  0.001), and in those undergoing axillary nodal surgery (60.4% vs 30.3%, P <  0.001) including the subset undergoing BCS (43.4% vs 8.5%, P < 0.001). Nodal metastasis rate was low and not statistically significant difference from the DCIS only group (P = 0.68). Following median follow-up of 110 months, 3% of patients had recurrent ipsilateral high-grade DCIS, and 4.2% developed invasive carcinoma. The subsequent ipsilateral invasion was of Grade 3 in 71.4% of patients with microinvasion vs 30.4% in DCIS without microinvasion (P = 0.02). Distant metastasis and breast cancer mortality were higher with microinvasion compared with DCIS only (1.2% vs 0.3%, P = 0.01 and 2.1% vs 0.8%; P = 0.005).<h4>Conclusions</h4>The higher breast cancer mortality with microinvasion indicates a more aggressive disease.British journal of cancerThe presentation, management and outcome of patients with ductal carcinoma in situ (DCIS) with microinvasion (invasion ≤1 mm in size)-results from the UK Sloane Project.PMC9726983C38317/A24043PRCRPG-Nov21\100001C17422/A25154Sharma NLitherland JProvenzano EStobart HSawyer EBrace-McDonnell SPinder SEThompson AMMylvaganam SDulson-Cox JEllis IOHilton BWallis MKearins OMaxwell AClements KDodwell DKirwan CShaaban AMfalseThe presentation, management and outcome of patients with ductal carcinoma in situ (DCIS) with microinvasion (invasion ≤1 mm in size)-results from the UK Sloane Project.<h4>Background</h4>The diagnosis, management and prognosis of microinvasive breast carcinoma remain controversial.<h4>Methods</h4>We analysed the outcomes of patients with DCIS with and without microinvasion diagnosed between 2003 and 2012 within the Sloane project.<h4>Results</h4>Microinvasion was recorded in 521 of 11,285 patients (4.6%), with considerable variation in reported incidence among screening units (0-25%). Microinvasion was associated with high-grade DCIS, larger DCIS size, comedo necrosis and solid, cribriform architecture (all P < 0.001). Microinvasion was more frequent in patients who underwent mastectomy compared with breast-conserving surgery (BCS) (6.9% vs 3.6%, P <  0.001), and in those undergoing axillary nodal surgery (60.4% vs 30.3%, P <  0.001) including the subset undergoing BCS (43.4% vs 8.5%, P < 0.001). Nodal metastasis rate was low and not statistically significant difference from the DCIS only group (P = 0.68). Following median follow-up of 110 months, 3% of patients had recurrent ipsilateral high-grade DCIS, and 4.2% developed invasive carcinoma. The subsequent ipsilateral invasion was of Grade 3 in 71.4% of patients with microinvasion vs 30.4% in DCIS without microinvasion (P = 0.02). Distant metastasis and breast cancer mortality were higher with microinvasion compared with DCIS only (1.2% vs 0.3%, P = 0.01 and 2.1% vs 0.8%; P = 0.005).<h4>Conclusions</h4>The higher breast cancer mortality with microinvasion indicates a more aggressive disease.2022-01-01T00:00:00Z2022 Dec2026-06-20T03:19:34.799Z2025-04-07T07:01:02.69ZS-EPMC97269833622440310.1038/s41416-022-01983-4