G M Clarke1, C M B Holloway2,3, J T Zubovits4,5, S Nofech-Mozes4,6, M Murray7, K Liu8, D Wang8, A Kiss9,10, M J Yaffe11,12. 1. Physical Sciences Platform, Sunnybrook Research Institute, Room C7-27c 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. 2. Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, Canada. 3. Department of Surgery, Sunnybrook Health Sciences Centre, Room T2-015 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. 4. Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Canada. 5. Department of Pathology, Scarborough and Rouge Hospital, 3030 Birchmount Road, Toronto, ON, M1W 3W3, Canada. 6. Sunnybrook Health Sciences Centre, Room E423a 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. 7. Physical Sciences Platform, Sunnybrook Research Institute, Room C7-48a 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. 8. Physical Sciences Platform, Sunnybrook Research Institute, Room C7-27a 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. 9. Research Design and Biostatistics, Sunnybrook Research Institute, Toronto, ON, Canada. 10. Institute of Health Policy, Management and Evaluation, University of Toronto, Room G106 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. 11. Departments of Medical Biophysics and Medical Imaging, Faculty of Medicine, University of Toronto, Toronto, Canada. martin.yaffe@sunnybrook.ca. 12. Physical Sciences Platform, Sunnybrook Research Institute, Room S6-57 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. martin.yaffe@sunnybrook.ca.
Abstract
PURPOSE: Linear tumor size (T-size) estimated with conventional histology informs breast cancer management. Previously we demonstrated significant differences in margin and focality estimates using conventional histology versus digital whole-mount serial sections (WMSS). Using WMSS we can measure T-size or volume. Here, we compare WMSS T-size with volume, and with T-size measured conventionally. We also compare the ellipsoid model for calculating tumor volume to direct, WMSS measurement. METHODS: Two pathologists contoured regions of invasive carcinoma and measured T-size from both WMSS and (simulated) conventional sections in 55 consecutive lumpectomy specimens. Volume was measured directly from the contours. Measurements were compared using the paired t-test or Spearman's rank-order correlation. A five-point 'border index' was devised and assigned to each case to parametrize tumor shape considering 'compactness' or cellularity. Tumor volumes calculated assuming ellipsoid geometry were compared with direct, WMSS measurements. RESULTS: WMSS reported significantly larger T-size than conventional histology in the majority of cases [61.8%, 34/55; means = (2.34 cm; 1.99 cm), p < 0.001], with a 16.4% (9/55) rate of 'upstaging'. The majority of discordances were due to undersampling. T-size and volume were strongly correlated (r = 0.838, p < 0.001). Significantly lower volume was obtained with WMSS versus ellipsoid modeling [means = (1.18 cm3; 1.45 cm3), p < 0.001]. CONCLUSIONS: Significantly larger T-size is measured with WMSS than conventionally, due primarily to undersampling in the latter. Volume and linear size are highly correlated. Diffuse tumors interspersed with normal or non-invasive elements may be sampled less extensively than more localized masses. The ellipsoid model overestimates tumor volume.
PURPOSE: Linear tumor size (T-size) estimated with conventional histology informs breast cancer management. Previously we demonstrated significant differences in margin and focality estimates using conventional histology versus digital whole-mount serial sections (WMSS). Using WMSS we can measure T-size or volume. Here, we compare WMSS T-size with volume, and with T-size measured conventionally. We also compare the ellipsoid model for calculating tumor volume to direct, WMSS measurement. METHODS: Two pathologists contoured regions of invasive carcinoma and measured T-size from both WMSS and (simulated) conventional sections in 55 consecutive lumpectomy specimens. Volume was measured directly from the contours. Measurements were compared using the paired t-test or Spearman's rank-order correlation. A five-point 'border index' was devised and assigned to each case to parametrize tumor shape considering 'compactness' or cellularity. Tumor volumes calculated assuming ellipsoid geometry were compared with direct, WMSS measurements. RESULTS: WMSS reported significantly larger T-size than conventional histology in the majority of cases [61.8%, 34/55; means = (2.34 cm; 1.99 cm), p < 0.001], with a 16.4% (9/55) rate of 'upstaging'. The majority of discordances were due to undersampling. T-size and volume were strongly correlated (r = 0.838, p < 0.001). Significantly lower volume was obtained with WMSS versus ellipsoid modeling [means = (1.18 cm3; 1.45 cm3), p < 0.001]. CONCLUSIONS: Significantly larger T-size is measured with WMSS than conventionally, due primarily to undersampling in the latter. Volume and linear size are highly correlated. Diffuse tumors interspersed with normal or non-invasive elements may be sampled less extensively than more localized masses. The ellipsoid model overestimates tumor volume.
Entities:
Keywords:
Breast cancer; Histologic size; Large-format histology; Lumpectomy; Tumor volume; Whole-mount serial sections
Authors: Brook K Byrd; Venkataramanan Krishnaswamy; Jiang Gui; Timothy Rooney; Rebecca Zuurbier; Kari Rosenkranz; Keith Paulsen; Richard J Barth Journal: Breast Cancer Res Treat Date: 2020-07-12 Impact factor: 4.872