SHG in Tumors: Scattering and Polarization
Tumor physiology, biochemistry, structural organization, and cellular composition are believed to make integrated contributions to cancer pathology. e tumor stroma for one includes the basement membrane, the extracellular matrix (ECM), and nonmalignant cells in the tumor, and plays signicant roles in tumor growth and metastasis [1,2]. e biochemical and phenotypic changes in stromal cells surrounding malignant tumor cells, including immune cells and connective tissue cells such as broblasts (a principal collagen-producing cell type), modify the synthesis and breakdown of key ECM components, resulting in a “reactive stroma” characteristic of neoplastic transformation and thus contributing to tumor progression and metastasis [1-4]. is key role that the “reactive stroma” plays in cancer pathogenesis has led to signicant interest in understanding the particular characteristics of reactive stroma that may provide prognostic value for predicting cancer pathogenesis or its outcome [5-8]. Since collagen is a key component of the ECM and is also believed to play important roles in cancer, recent years have seen a burgeoning interest in monitoring the second-harmonic generation (SHG) signal from brillar collagen in tumor stroma, with the idea that it may provide diagnostic or predictive value in comparison of normal versus malignant tissue [9-16, and other references herein].