Abstract
Aims: The aim was to identify at least 250 cases of LCIS via the NHSBSP to ascertain if LCIS can be screen detected as well as identifying its prognostic factors and to establish recommendations for its treatment. Methods: LCIS cases were identified from screening centre databases. Mammograms and pathology were reviewed and correlated to identify which cases were truly screen detected. Subsequent breast cancers were identified. Results: 366 cases of LCIS were identified. Pathology blocks were available on 205. On review we were unable to confirm a diagnosis of LCIS in 22, 19 were reclassified as DCIS and 164 were confirmed as LCIS. Of these 164 LCIS cases, 99 presented with mammographic calcifications, 28 with a mass and 50 with distortion. 88 cases presented with calcification alone, 28 were associated solely with the LCIS and were large enough to be visible on mammography fulfilling our definition for screen detected LCIS. 60 cases were incidental with 9 cases of calcification within both LCIS and benign changes and 51 in benign changes only. With a total of 701.3 women years of follow up, 7 women with screen detected (7/28) and 10 with incidental LCIS (10/135) developed breast cancer. With event rates of 49.1/1000 women years in the screen detected group and 17.9/1000 in the incidental group (relative risk of 2.66, 95% CI 1.03-6.86; p=0.04). There was no difference in the mammographic features of the two groups. Conclusions: LCIS can be detected on mammography. Screen detected LCIS is associated with a higher subsequent cancer risk than incidental LCIS.