TILs therefore represent a prognostic tool in the treatment of CRC, a high density of immune cells being associated with good outcome independently of other established prognostic markers. We investigated the relation between infiltrates of immune cells in liver metastases of CRC and response to chemotherapy using immunohistochemical staining. Liver samples from 33 patients with metastasized CRC (samples from 22 patients were used buy Dabrafenib as training set and samples from 11 patients as validation set) were analyzed. Patients underwent surgery after the initial workup appeared to warrant complete surgical removal of the liver metastases. In these patients,

only partial resections were possible and these patients ZD1839 chemical structure received palliative chemotherapy afterwards. Statistically significant differences within the

training set allowed prediction of response to chemotherapy by evaluation of the invasive margin of the liver metastasis. Complete sections were examined using an automated high-resolution microscope. The observed differences (see figure, CD3 positive cells stain dark red, panel A shows a sample with high infiltrate density, panel B shows a sample from another patient with low density) in TIL densities also translated into differences in the time to progression under chemotherapy, where higher numbers of positively stained cells were associated with longer intervals. The difference between the groups with either response or no response to chemotherapy in time to progression was statistically significant (Mann-Whitney-U, p < 0.001, two-tailed, z = −3,961, n = 33). Our results suggest that the immune system influences efficacy of chemotherapy. We have first evidence that the impact of the local immune response on the clinical course is a general phenomenon, not limited to the primary tumor but also present in metastatic lesions. Erastin purchase This might have implications for the assessment of therapy options. Poster No. 79 Association of an Extracellular Matrix Gene Cluster with Breast Cancer Prognosis and Endocrine Therapy Response Jozien Helleman 1 , Maurice P.H.M. Jansen1, Kirsten Ruigrok-Ritstier1,

Iris L. van Staveren1, Maxime P. Look1, Marion E. Meijer-van Gelder1, Anieta M. Sieuwerts1, Stefan Sleijfer1, Jan G.M. Klijn1, John A. Foekens1, Els M.J.J. Berns1 1 Medical Oncology, Erasmus MC, Rotterdam, The Netherlands Therapy resistance is a major problem in the treatment of breast and ovarian cancer. We observed in our expression profiling study in breast cancer a gene cluster of ECM related genes, with a similar expression pattern, that was associated with first-line tamoxifen response in advanced breast cancer (Jansen et al. J Clin Oncol 2005). We subsequently validated these ECM genes (COL1A1, FN1, LOX, SPARC, TIMP3, TNC) in 1286 breast carcinomas using qPCR. High TIMP3, FN1, LOX and SPARC expression is associated with a worse prognosis for 680 untreated lymph node negative patients (p < 0.