Near infrared tuned gold nanoshells have been developed to enhance the contrast of optical coherence tomography (OCT) images, and we have completed a systematic study which quantifies and optimizes the specifications of nanoshells that provide improved efficacy of OCT imaging and photothermal ablation of cancer. The optical properties of gold nanoshells, such as scattering, absorption, and asymmetry values were calculated with Mie scattering theory. For comparison and experimental quantifications, scattering coefficients were extracted from OCT images using Extended Huygens-Fresnel (EHF) principle based algorithms. With the addition of Her2 conjugated nanoshells, ex vivo OCT images of human breast cancer tissue, which express signatures of Her2/neu, provide significant contrast in comparison to the normal and malignant controls. As an extended study of dual NIR absorbing/scattering nanoshells for integrated cancer imaging and therapy in vitro, combined OCT imaging and photothermal tumor ablation was performed in vivo. Results showed that gold nanoshells selectively accumulated in the tumorous regions and enabled clear differentiation of tumor. Tumor regression by the photothermal ablation using NIR tuned nanoshells was also reported. Our studies have demonstrated that nanoshells can be designed specifically for diagnostic and therapeutic purposes.