Abstract P1-06-06: Alteration of stromal collagen fiber orientation in DCIS

Abstract

Abstract Approximately 20% of new diagnoses of breast cancer are ductal carcinoma in situ (DCIS), a non-invasive form of breast cancer. Treatment decision-making for DCIS is challenging since current predictors of disease-free survival are limited, so that most women are presented with options for surgery, radiation and tamoxifen - all options with consequences for quality of life. Prior studies of prognostic factors for DCIS have focused on morphologic, genetic, and protein expression patterns of the DCIS cells. However, laboratory evidence suggests that the tumor microenvironment may play a key role in tumor invasion and progression. Collagen is the most abundant component of the stroma surrounding the breast ducts in which cancers develop. We previously observed that, in invasive breast cancer, tumors with greater numbers of collagen fibers aligned perpendicularly from the tumor were more likely to predict poor survival than tumors with collagen fibers in primarily parallel patterns near the tumor boundary (Conklin Am J Pathol 2011). To improve our ability to predict breast cancer outcomes in women with DCIS, we examined the alignment of collagen adjacent to ducts affected by DCIS to test whether alignment patterns were similar to patterns observed in tissue labeled as “normal” from biopsy and surgical sections. We evaluated collagen alignment in 255 Wisconsin women diagnosed with DCIS in 1997-2000 and followed for a median of 11.2 years (range 1-15). Stromal collagen alignment was evaluated from routine H&E tissue slides prepared at the time of diagnosis using second harmonic generation (SHG) microscopy, a label-free multiphoton laser scanning technique that selectively images collagen. SHG images were acquired and evaluated for 3-5 regions on each DCIS and normal slide for each patient; the angles of collagen fibers with respect to the DCIS lesion/stroma boundary were calculated using customized imaging software. Data for the distribution of angles were compared for normal ducts and DCIS lesions using compositional data analysis with the number of fibers totaled according to 5-angle bins (1-5, 6-10, 11-15, …, 86-90 degrees). Repeated measures linear regression models were fit to log-transformed ratios of binned counts as a function of tissue type. Dependence among repeated counts within a single region was modeled using an unstructured variance-covariance matrix. Dependence among measurements within a single subject was modeled using a compound symmetry correlation structure. Overall, the distribution of collagen fiber angles from DCIS lesions differed significantly (P = 0.0002) from the distribution of collagen fibers surrounding normal ducts. Collagen fibers surrounding DCIS lesions were 11-18% more likely to orient at 75-90 degrees relative to the lesion boundary than fibers surrounding normal ducts; fibers were more similarly aligned in both DCIS lesions and normal ducts at other smaller angles. These results underscore the relevance of the tumor microenvironment, in particular the arrangement of the collagen fiber matrix. Planned data analysis will next examine whether collagen fiber alignment patterns differ between DCIS patients who did and did not experience a second breast cancer diagnosis over the course of follow-up. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-06-06.