Intraoperative radiotherapy (IORT) has been investigated as an exclusive adjuvant treatment option for early-stage breast cancer (BC). We analysed our experience on the technical aspects of this ...innovative approach in terms of identification of breast volume actually to be treated during IORT.
A total of 315 patients at low risk of breast cancer recurrence underwent IORT as exclusive treatment after breast-conservative surgery. To evaluate the breast volume actually irradiated with IORT, we considered a sample of eight patients, chosen retrospectively as having enough clips to identify the tumour bed and IORT site in computed-tomography (CT). The clinical target volume (CTV) was assessed for each patient with two different methods: the first, cc-IORT, was considered during surgery according to the chosen collimator diameter and glandular thickness, while the second, cc-CT, was evaluated through computed-tomography performed after surgery. The cc-CT CTV was obtained by contouring the cc-IORT on the CT section on the basis of the clips placed by the surgeon on the resection margins.
In our experience, the 5-cm (50%) and the 6-cm (36%) diameter collimators have been the ones, used the most. The diameter of the collimator used did not appear to adversely affect the satisfactory aesthetic result. The comparison between CTVs showed that glandular breast volume contoured with CT (cc-CT) appeared to be three fold larger than the target identified at surgery and included in the area of chosen collimator (cc-IORT).
The actual volume of breast gland irradiated with the IORT procedure appears to be larger than expected. This may be due to the area being prepared for IORT by placing tissue compactly.
Abstract 3879
The use of early (interim) positron emission tomography (PET) restaging during front-line therapy in Hodgkin's lymphoma (HL) has considerably increased in clinical practice as an early ...recognition of treatment failure allows patients to be addressed to more intensive treatment regimens.
Between June 1997 and June 2009, 304 newly-diagnosed Hodgkin's lymphoma patients (147 early-stage and 157 advanced-stage) were treated with the ABVD regimen at two Italian institutions. Patients underwent to a PET staging and restaging at baseline, after 2 cycles of therapy and at the end of the treatment.
53 patients showed a positive interim PET and only 13/53 (24.5%) achieved a complete response (CR), whereas 251 patients showed a negative PET and 231/251 (92%) remained in CR. Comparison between interim PET-positive and interim PET-negative patients indicated a significant association between PET findings and 9-year progression-free survival (p=0.0000) and 9-year overall survival (p=0.0000), with a median follow-up of 31 months.
Among the early-stage patients, 19 had a positive interim PET and only 4 (21%) achieved a CR; among the 128 negative interim PET patients, 122 (97.6%) obtained a CR. In the advanced-stage subset, 34 patients showed a persistently positive PET (with only 9/34, 26.4% in CR), whereas 123 showed a negative interim PET, with 109 (88.6%) remaining in CR.
Our results confirm the role of early PET as a significant step forward for the management of both early and advanced-stage HL patients, offering the potential for an immediate switch to high-dose treatments, if required.
No relevant conflicts of interest to declare.
Abstract 2494
Burkitt lymphoma (BL) is currently listed in the WHO classification of lymphoid tumors as a single genetic and morphological entity with variation in clinical presentation. In ...particular, three clinical subsets of BL are recognized: endemic (eBL), sporadic (sBL) and immunodeficiency associated (ID-BL). Each affects different populations and can present with different features. So far, possible differences in their gene expression profiles (GEP) have not been investigated. In this study we aimed to 1) assess whether BL subtypes present with differences in their GEP; 2) investigate the relationship of the different BL subtypes with the non-neoplastic cellular counterparts; 3) Identify genes and programs specifically deregulated in BLs and possibly contributing to the malignant phenotype.
We studied by GEP 128 cases of B-cell derived malignancies and 20 samples of normal B-cell subpopulations GEP analysis. In particular, we included 40 BLs (13 eBLs, 21 sBLs 6 HIV-BLs), 40 follicular lymphomas, 10 chronic lymphocytic leukemias, 10 GCB-type diffuse large B-cell lymphomas, 10 ABC-type DLBCL, 5 primary mediastinal B-cell lymphomas, 13 HIV-related DLBCL, as well as 10 germinal center (GC), 5 naïve and 5 memory cells samples. GEP results were confirmed by dividing BL cases into training and test subgroups. In addition, as further validation, we performed immunohistochemistry (IHC) on tissue microarrays containing 85 BL cases as well as functional assays in vitro and in vivo, by focusing on the role of RBL2, a tumor suppressor gene involved in cell cycle control and mutated in eBL. Specifically, we used cell transfection and shRNAs (for mimicking MYC over-expression and RBL2 silencing), soft agar and invasion capability assays, and xenografted mouse models.
First, we found that BLs constitute a unique molecular entity, with a relatively homogeneous GEP, distinct from other B-cell malignancies. Indeed, by unsupervised analysis all BLs clearly clustered apart of other lymphomas. However, by supervised analysis, we found that BL subtypes presented slight differences in their GEPs. Particularly, eBLs and ID-BLs appeared to be almost identical, diverging from sBLs. Specifically, they varied for genes involved in cell cycle control, BCR-signaling, and TNF/NFKB-pathways. Of note, eBLs and ID-BLs on one hand, and sBLs on the other (roughly corresponding to EBV+ vs. EBV− cases) also differed for genes target of mi-R127a, which is altered in EBV+ cases as a direct consequence of viral integration.
To further investigate cell cycle regulation in BLs, we inferred a network of RBL2-depending genes by reverse engineering, by uncovering possible RBL2 transcriptional targets. Interestingly, we found that eBL and sBL diverged for genes belonging to such network. Notably, we provided evidences that RBL2 can cooperate with MYC in inducing a neoplastic phenotype in vitro and in vivo. In particular, lymphoblastoid cells engineered to carry both MYC over-expression and RBL2 silencing presented with increased colony formation and matrix invasion capabilities, and higher efficiency in inducing tumor formation in nude mice if compared to single transfectants (MYC+ or RBL2−).
Moreover, as the present WHO classification does not definitely identify the counterpart of eBL, we compared BLs GEP to those of normal B-cells. We found that all BL subtypes were intimately related to GC cells (by showing an early stage GC differentiation arrest), differing from them for molecules specially involved in cell proliferation, immune response, and signal transduction.
Finally, as further validation of GEP, we studied by IHC the expression of SPARC and CYR61, two molecules involved in human tumorigenesis. Indeed, they turned out to be consistently expressed by neoplastic elements in all instances, as indicated by GEP analysis.
Our study provided substantial insights on the pathobiology of BLs, by offering novel evidences which may be relevant for its classification and possibly future treatment.
No relevant conflicts of interest to declare.
Centrality descriptors are widely used to rank nodes according to specific concept(s) of importance. Despite the large number of centrality measures available nowadays, it is still poorly understood ...how to identify the node which can be considered as the `centre' of a complex network. In fact, this problem corresponds to finding the median of a complex network. The median is a non-parametric and robust estimator of the location parameter of a probability distribution. In this work, we present the most natural generalisation of the concept of median to the realm of complex networks, discussing its advantages for defining the centre of the system and percentiles around that centre. To this aim, we introduce a new statistical data depth and we apply it to networks embedded in a geometric space induced by different metrics. The application of our framework to empirical networks allows us to identify median nodes which are socially or biologically relevant.
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