There is a considerable interest in the developing new diagnostic techniques allowing noninvasive tracking of the progress of therapies used to treat a cancer. Raman imaging of distribution of phthalocyanine photosensitizers may open new possibilities of Photodynamic Therapy (PDT) to treat a wide range of neoplastic lesions with improved effectiveness of treatment through precise identification of malignant areas. We have employed Raman imaging and Raman spectroscopy to analyze human breast cancer tissue that interacts with photosensitizers used in the photodynamic therapy of cancer. PCA (Principal Component Analysis) has been employed to analyze various areas of the noncancerous and cancerous breast tissues. The results show that the emission spectra combined with the Raman images are very sensitive indicators to specify the aggregation state and the distribution of phthalocyanines in the cancerous and noncancerous breast tissues. Our results provide experimental evidence on the role of aggregation of phthalocyanines as a factor of particular significance in differentiation of the normal and tumourous (cancerous or benign pathology) breast tissues. We conclude that the Raman imaging reported here has a potential to be a novel and effective photodynamic therapeutic method with improved selectivity for the treatment of breast cancer.