Chordoma is a rare malignant tumor of the skull base and axial skeleton, with an incidence of less than 0.1/100,000 per year. Patients with advanced chordoma have a poor prognosis due to locoregional recurrence with infiltration and destruction of surrounding bone and soft tissue. Cytotoxic chemotherapy or other systemic therapies have not been proven to be effective for these diseases. Therefore, several molecularly targeted therapies have been proposed as potentially beneficial, including tyrosine kinase inhibitors such as imatinib, sorafenib, lapatinib, and others. We present three cases of advanced chordoma treated with molecular targeted therapies: a 52-year-old Caucasian man, a 72-year-old Caucasian woman, and a 38-year-old Caucasian woman. Chordoma has few systemic treatment options and they have limited benefit. Randomized trials with large patient numbers are unfeasible in this rare disease. Targeted therapy might be a reasonable alternative treatment for chordoma. Still, new treatment strategies are needed for this rare disease.

Among patients with breast cancer, pathological complete response (pCR) to neoadjuvant chemotherapy (NAC) is an important prognostic predictor of survival. This study aimed to investigate the relationship between platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) along with overall pCR. A total of 150 patients with breast cancer who were first administered NAC and then operated on were retrospectively evaluated. Neutrophil-lymphocyte ratio and PLR obtained from the complete blood count analysis performed immediately before NAC treatment were analyzed. The cut-off value was calculated as 150 for PLR and 2.24 for NLR. We studied the predictive value of NLR and PLR levels for the pathologic response of breast cancer to NAC. Pathological complete response was observed in 34.7% (n = 52) of the patients, pCR in the breast in 42.7% (n = 64), and that in the axilla in 44% (n = 66). There was a statistically significant difference between the pCR rates according to the PLR levels (p = 0.013). In addition, a statistically significant difference was found in the pCR rates in the breast and axilla according to PLR levels (p = 0.018, p = 0.009). Patients with low PLR in the human epidermal growth factor receptor 2 (HER-2) group had significantly higher axillary pCR rates than in those with high PLR (p = 0.019). A low PLR level showed high chemotherapy sensitivity independent of molecular subtypes in the treatment of breast cancer with NAC. The PLR level can serve as a predictive marker of the therapeutic effect of NAC on the breast and axilla. Low PLR levels in HER-2 enriched groups can predict pCR in the axilla.

Objective: To determine the diagnostic value of breast and axillary maximum standard uptake (SUVmax) values for predicting ypT0 and ypN0 separately. Study Design: A descriptive study. Place and Duration of Study: Department of Medical Oncology, Haydarpasa Numune Training and Research Hospital, between May 2017 and September 2020. Methodology: Consecutive patients with operated breast cancer (BC) after neoadjuvant chemotherapy (NAC) were evaluated. SUVmax on FDG-PET/CT after NAC at both primary tumour (postSUVmax-T) and axillary lymph nodes (postSUVmax-N) were assessed to predict the ypT0 and the ypN0, respectively. Results: Clinically meaningful correlation was detected between postSUVmax-N with ypN0 in patients with human epidermal receptor-positive (Her2+) and triple-negative (TN) BC (in Her2+ BC: r=0.596, p <0.001, in TN BC: r=0.782, p = 0.001). The postSUVmax-N predicted ypN0 with 90.5% positive predictive value (PPV) and 85.7% negative predictive value ( NPV) in patients with Her2+ and TN BC. The postSUVmax-T predicted ypT0 with 87.5% PPV and 100% NPV in patients with TN BC (AUC: 0.938, P <0.01) Conclusion: According to this study's findings, the FDG-PET/CT may be an alternative to sentinel lymph node biopsy (SNB) to protect patients from axillary lymph node dissection when the expected FNR of the SNB is high in patients with Her+ and TN BC.

E15009 Background: Colorectal cancer is a major cause of mortality worldwide. Survival has been improved by usage of bevacizumab. Our study aimed to analyze survival and prognostic factors in metastatic colorectal cancer patients treated with first-line bevacizumab. Methods: Files of patients were examined retrospectively and 360 patients treated with first-line bevacizumab were included. Data regarding age, gender, family history, location of the primary, histopathology, KRAS status, surgery and chemotherapy were acquired from the files. Overall response rates (ORR) to chemotherapy, progression and exitus dates or dates of last examination were recorded. Median progression-free and overall survival (PFS and OS) were calculated. Survival was analyzed with Kaplan-Meier method. Log-rank test and Cox regression model were used for univariate and multivariate analysis, respectively. Results: 201 (%55,8) of the patients were male and 159 (%44,2) were female. Median age at the time of the diagnosis was 59.5. 260 patients (%72,2) had initially stage IV disease. KRAS was mutant in 125 patients (%34,7). Median PFS was 8.5 months, median OS was 25.3 months and ORR was %51,4. Median PFS was 8.2 and 9.5 months, median OS was 30.4 and 28.1 months, ORR was %62,6 and %58.4 in KRAS wild type and mutant groups, respectively. In patients with left colon cancer median PFS and OS (9.6 and 27.1 months) were superior compared to patients with right colon cancer (7.3 and 19.4 months) (p = 0.005 and 0.016, respectively). Location of the primary, histopathologic grade, primary surgery, metastasectomy and KRAS status affected overall survival significantly (p < 0.05) in univariate analysis. In multivariate analysis, histopathologic grade (p = 0.034) and metastasectomy (p = 0.001) were independent prognostic factors. Conclusions: In our study, response rates and survival of metastatic colorectal cancer patients treated with first-line bevacizumab were similar to previous studies. Left colon cancer patients had superior median PFS and OS compared to right colon cancer patients as shown in recent studies. Histopathologic grade and metastasectomy were independent prognostic factors in correlation with literature.

Background: Metastasectomy is a cornerstone of multimodal management in metastatic colorectal cancer (mCRC), yet contemporary real-world data focusing specifically on RAS wild-type (RAS-WT) disease remain limited. We aimed to evaluate survival outcomes and prognostic factors associated with metastasectomy in patients with RAS-WT mCRC using a large national multicentre registry. Methods: This retrospective cohort study utilized data from the ONKO-KOLON Türkiye registry. A total of 1079 patients with pathologically confirmed KRAS/NRAS wild-type mCRC were identified and categorized according to receipt of metastasectomy. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan–Meier method and compared with log-rank tests across multiple clinically relevant time origins, including metastatic diagnosis, initial colorectal cancer diagnosis, and time of metastasectomy. Prognostic factors within the metastasectomy cohort were assessed using univariate Cox proportional hazards models. Serum CEA and CA19-9 were analyzed after log₁₀ transformation. Results: Among 1079 patients, 185 (17.1%) underwent metastasectomy. Patients receiving metastasectomy demonstrated significantly longer OS compared with those managed non-surgically when survival was calculated from the time of metastatic diagnosis (hazard ratio [HR] for death 0.36, 95% CI 0.27–0.47; p < 0.001), as well as improved PFS (HR for progression or death 0.39, 95% CI 0.30–0.52; p < 0.001). The survival advantage remained consistent when OS was measured from the time of initial colorectal cancer diagnosis (HR 0.37, 95% CI 0.25–0.50; p < 0.001). Median OS following metastasectomy was 43 months (95% CI 31.4–45.6). In univariate analyses within the metastasectomy cohort, higher baseline CA19-9 levels were significantly associated with inferior OS when analyzed both as a continuous variable (per log₁₀ increase; HR 1.81, 95% CI 1.20–2.75; p = 0.005) and as a categorical variable (above vs. below threshold; HR 0.37, 95% CI 0.16–0.86; p = 0.021). Other clinicopathologic factors, including age, CEA, tumor sidedness, grade, MSI status, and metastatic burden, were not significantly associated with survival. Conclusions: In this large, real-world national cohort of RAS-WT mCRC, metastasectomy was strongly associated with prolonged survival across multiple clinically relevant time frames. Within surgically treated patients, baseline CA19-9 emerged as the most informative prognostic marker, while traditional clinicopathologic variables showed limited discriminatory value. These findings highlight the importance of careful patient selection and support further prospective studies integrating molecular and biomarker-based strategies to refine prognostication and optimize surgical decision-making in RAS-WT mCRC.

Objective: To evaluate the effect of FDG-PET/CT in the radiological imaging of breast cancer (BC) patients planned for neoadjuvant treatment (NAT), on the clinical prognostic stage (CPS). Study Design: A descriptive study. Place and Duration of Study: Haydarpasa Numune Training and Research Hospital, Istanbul, Turkey, between June 2014 and September 2020. Methodology: Consecutive patients with stage I-III breast cancer (BC) who were planned for neoadjuvant treatment (NAT). The distribution of CPS detected by both conventional radiological methods (c-CPS) and FDG-PET/CT (PET-CPS) were compared. Results: Significant upstaging on CPS was detected with the addition of FDG-PET/CT to conventional imaging methods 25/121 (20.7%) patients (p <0.001). In the c-CPS stage, IB, IIA, IIB, IIIA, IIIB patients, the stage change rate was 22.7%, 28.6%, 37.5%, 50%, and 9.1%, respectively. There was no change in patients with c-CPS stage IA and IIIC. There was a significant change in the cN stages (p <0.001), while no significant change was detected in the cT stages of the patients (p = 0.180). Upstaging was detected in 5/16 (6.3%, p=0.034), 14/71 (19.7%, p <0.01), 15 / 30 (50%, p <0.01) of initially cN 0, 1, 2 patients, respectively (p<0.001). Conclusion: The change in CPS was due to nodal upstaging. The effectiveness of including FDG-PET/CT in the initial radiological imaging in patients planned for NAT should be evaluated with prospective studies evaluating treatment choices to be used in NAT.