(F-202) Differences in two optical signatures of metastasis among demographic groups

Introduction:: Cancer mortality rates for African-American (AA) patients are frequently higher than for Caucasian-American (CA) patients. While differences in socioeconomic status and patient mistrust of the health care system play a role in this disparity, another major contributor is the lack of proper representation of minorities in research cohorts. Our laboratory has previously demonstrated a light scattering method to help predict metastases in breast and colon cancer patients. This method is based upon the scattering directionality of Second Harmonic Generation (SHG) light, and has promise to improve postsurgical treatment decision-making for these patients, especially those with less financial resources. To evaluate the significance of patient race on the design of future research studies for the advancement of this technique, here we evaluate this optical signature and collagen fiber alignment, a related prognostic signature, in Stage I Colon Adenocarcinoma from African-American patients versus Caucasian-American patients.


Materials and Methods:: Formalin-fixed paraffin embedded sections from 11 AA and 77 CA patients with Stage I Colon Adenocarcinoma were secured from archives of the University of Rochester Medical Center (URMC). Use of patient samples was approved by the Institutional Review Board at URMC. Calibrated SHG images in both the forwards and backwards scattering directions were generated from each sample, with 3 image pairs generated in each of 3 region types (tumor bulk, tumor/stromal interface, and far from tumor) per section. As previously described, the forwards-to-backwards scattering ratio (F/B) was calculated for each imaged region, and averaged to produce a single F/B value for each of the three region types in each patient. In addition the CT-FIRE software package was used to assess collagen fiber alignment for each forward-scattered SHG image, and the average fiber alignment was calculated for each region type for each patient.


Results, Conclusions, and Discussions:: In patients with Stage I Colon Adenocarcinoma, we find a statistically significant difference in F/B between the AA and CA populations in the tumor/stromal interface (p=0.038), but not tumor bulk (p=0.14) nor far from tumor (p=0.40). We did not find a statistically significant difference in age (p=0.10), or BMI (p=0.30) between the two groups.

Our previous work in breast cancer has shown that F/B has the best prognostic value when measured in the tumor/stromal interface, but not the tumor bulk, of Invasive Ductal Carcinoma. Interestingly, here in patients with Stage I Colon Adenocarcinoma, we find a statistically significant difference in F/B between the AA and CA populations in the tumor/stromal interface (p=0.038), the region that is most prognostic in breast tumors. We found no difference in F/B in tumor bulk (p=0.14) nor far from tumor (p=0.40). One possible reason for these differences could be confounding variables that are also different between the two populations, however in preliminary analysis we did not find a statistically significant difference in age (p=0.10), or BMI (p=0.30) between the two groups. This difference between groups in baseline F/B suggests the possibility that there is a difference between groups in the relationship between F/B and metastatic outcome. Therefore, as we design future studies exploring the relationship between F/B and metastatic outcome, we must take care to assess the role of patient demographics in study cohorts.


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