Prediction of breast cancer response to neoadjuvant chemotherapy in different biological breast cancer subtypes using diffuse optical tomography

Abstract Background: Optical-based imaging modalities play an important role in assessing breast tissue composition by measuring optical property contrast from endogenous chromophores. The advantages of optical techniques are the use of non-ionizing radiation, ease of use, and relatively low cost. The primary objective of this study is to examine changes in optically derived parameters (i.e., deoxy-hemoglobin concentration, ctHHb) from different breast cancer subtypes under neoadjuvant chemotherapy (NAC), and correlate with tumor pathologic complete response (pCR). Methods: This retrospective study evaluated 89 tumors in total divided into three distinct subtypes: HR+/HER2- (n=34), HER2+ (n=27), and TNBC (n=28). All patients were imaged at baseline, before starting NAC (TP0), and two weeks after receiving one cycle of taxane-based chemotherapy (TP1). HER2+ breast cancer patients also received HER2-target therapy. pCR was defined as complete absence of invasive carcinoma in the breast and lymph node(s) (ypT0/is ypN0 Mx) at the time of surgery. Whole breast volume was imaged by a diffuse optical tomography breast imaging system (DOTBIS) using low-intensity near-infrared light. ctHHb tumor volume concentration was normalized by the non-affected health tissue ctHHb mean value (ctHHbN). For each molecular subgroup, we conducted an independent-samples t-test to determine if there was a difference in ctHHbN levels at TP1 compared to TP0 between patients with a pCR and non-pCR. Significance was assumed at a confidence interval of 95% (α = 0.05). Results: In total, 69 patients were imaged with DOTIBS at both time points, TP0 and TP1. HR+/HER2-, TNBC and HER2+ accounted for 32% (n=23), 37% (n=22) and 30% (n=22), respectively. The ratio between ctHHbN levels measured at TP1 and TP0 was statistically significantly lower in the pCR group than non-pCR for the HER2+ and HR+/HER2- molecular subgroups, Table 1. Conclusion: Aligned to the current practices in breast cancer management based on the characterization of breast cancer subtypes, our work evaluated changes in DOTBIS optically derived features and pCR status for different subtypes. We observed that ctHHbN levels change after two weeks of NAC and these changes are modifiable according to pCR status and are dependent on immunophenotype. Table 1.Ratio between ctHHbN levels measured at TP1 and TP0 between pCR and non-pCR according to different molecular subtypes.Molecular SubtypepCR (mean ± SD )non-pCR (mean ± SD )p-valueHR+/HER2- (n=23)0.77 ± 0.22 (n=6)1.14 ± 0.24 (n=17).01HER2+ (n=24)0.74 ± 0.30 (n=15)1.54 ± 0.98 (n=9).04TNBC (n=22)0.96 ± 0.38 (n=4)1.29 ± 0.37 (n=18).18Bold values indicate statistical significance at p<.05 level. Citation Format: Mirella L Altoe, Kevin M Kalinsky, Hua Guo, Hanina Hibshoosh, Mariella Tejada, Katherine D Crew, Melissa K Accordino, Meghna S Trivedi, Alessandro Marone, Hyun K Kim, Andreas H Hielscher, Dawn L Hershman. Prediction of breast cancer response to neoadjuvant chemotherapy in different biological breast cancer subtypes using diffuse optical tomography [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-02-04.