Objective In this study, primary tumors’ fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) uptake in luminal A, luminal B, triple-negative, and human epidermal growth factor receptor type-2 subtypes of breast cancer was evaluated. In addition, the relationship between the primary tumor maximum standardized uptake value (SUV_max) value and the presence of distant metastasis and axillary involvement was evaluated. Patients and methods Whole-body ¹⁸F-FDG PET/computed tomography (CT) imaging of 493 patients (mean age; 54.6±13.2 years) diagnosed with primary breast cancer were analyzed retrospectively. PET/CT imaging was obtained 60 min after the intravenous administration of ¹⁸F-FDG. ¹⁸F-FDG uptake of the lesions was assessed by calculating the SUV_max. Histopathological analyses were carried out on the basis of biopsy samples before PET/CT. For histopathological staging, the Scarff Bloom Richardson classification system was utilized, and patients were classified into luminal A, luminal B, triple-negative, and human epidermal growth factor receptor type-2 molecular subtypes. Results 82.9% of the patients had invasive ductal carcinoma, 5.8% had invasive lobular carcinoma, 4.2% had apocrine carcinoma, 3.8% had mucinous carcinoma, and 3.4% has mixed carcinoma. Although the highest mean SUV_max was calculated in apocrine tumors (12.4±7.2), the lowest mean SUV_max was calculated in lobular carcinoma (6.8±4.6), and a statistically significant difference was found between the histological groups (P<0.001). ¹⁸F-FDG uptake was reported to be significantly higher in the triple-negative subtype than the luminal types, and in the luminal B subtype than the luminal A subtype. A statistically significant relation was found between primary tumor SUV_max and distant nodal, organ metastasis (P=0.003 and <0.001, respectively). Conclusion Increased primary tumor ¹⁸F-FDG uptake was associated with aggressive molecular subtypes in this study. The relationship of distant nodal and organ metastasis with primary tumor SUV_max showed that increased ¹⁸F-FDG uptake is important in terms of management of therapy and prognosis.

Objective: Prognostic effect of KRAS mutation and side of tumor in colorectal cancer is a highly controversial subject. Therefore, we evaluated the association between FDG uptake pattern in F-18-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (F-18-FDG PET/CT) imaging and KRAS mutation and tumor localization in patients with a diagnosis of colon cancer and assessed the effects of these three factors on prognosis and survival. Methods: Eighty-three patients with colorectal cancer were retrospectively induded in this study. F-18-FDG PET/CT study was performed for pretreatment staging. The maximum standardized uptake value (SUVmax) of the primary tumor and survival data of patients were compared between groups. KRAS mutations were detected with the help of real-time Polymerase Chain Reaction technique through genomic DNA extracted from paraffin-embedded tumor tissue blocks. Tumor lesions with potential KRAS mutations were classified as mutant KRAS and wild type. Results: Twenty five patients were female while 58 were male. The mean age of the patients was 59.8 +/- 11.3 years. Mean follow-up was 35.5 +/- 18.9 months. Primary tumor was localized in the left colon in 83.1% of patients and in the right colon in 16.9%. KRAS mutation was detected in 54.2% (n=45) of patients. Mean SUVmax of patients with primary tumor was estimated to be 21.1+9.1 (range= 6.0-47.5). Mean tumor SUVmax of patients with a KRAS mutation (24.0 +/- 9.0) was found to be significantly higher than those without KRAS mutation (17.7 +/- 8.2) (p=0.001). Mean survival was significantly shorter in patients with locoregional nodal metastasis than in patients without locoregional nodal metastasis as well as in patients with distant nodal metastasis than in patients without distant nodal metastasis and in patients with organ metastasis in initial PET/CT than in patients without organ metastasis. Also, mean survival was nearly statistically-significantly shorter in patients with tumors located in left colon (34.2 +/- 19.4) than in right colon (43.2 +/- 14.6) (p=0.059). However, we found no significant impact of KRAS mutation on survival. Conclusion: In our study, we found that tumor localization had no significant effect on prognosis in patients with colon cancer. On the other hand, FDG uptake was observed to be higher in the presence of KRAS mutation and it was concluded that coexistence of KRAS mutation with higher SUVmax is a negative prognostic factor.

Aim: Aim of study is to compare the results of Gallium-68-prostate-specific membrane antigen (⁶⁸Ga-PSMA) and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography(PET)/computed tomography (CT), to evaluate the correlation between PET findings and the level of PSMA, Claudin (Clau) 1, 4, and 7 receptors obtained by immunohistochemical (IHC) analysis, and to determine potential predictive and prognostic values in TNBC. Methods: Forty-seven lesions of 42 subjects diagnosed TNBC both underwent PET/CT scan for preoperative staging/restaging were prospectively included study. PSMA, Clau 1, 4, and 7 expressions were IHC evaluated from the biopsy samples of the primary tumor (PT). Maximum standardized uptake value(SUV max) of the PT, lymph node, and distant organ metastases (DOMs) on ¹⁸F-FDG and ⁶⁸Ga-PSMA PET/CT were compared with PSMA, Clau 1, 4, and 7 receptor expressions. Results: IHC analyses on 29 BC lesions to demonstrate Clau expression showed 86% (25/29) Clau 1, 86% (25/29) Clau 4, 45% (13/29) Clau 7, and 48% (14/29) PSMA-positive. The mean DOM (SUVmax) was 15.5 ± 11.6 for ¹⁸F-FDG and 6.0 ± 2.9 for ⁶⁸Ga-PSMA. Axial diameter of BC PT had a significant positive correlation with ¹⁸F-FDG SUVmax, ⁶⁸Ga-PSMA SUVmax, and PSMA scores. BC lesions ⁶⁸Ga-PSMA SUVmax had a significant negative correlation with the Ki-67 index. Axial diameter of the primary tumor had significant negative correlation with Clau 7 scores (r = −0.409, P = 0.034). Absence of Clau 1 expression found to significantly increase the rate of DOM (100% vs. 28%) (P = 0.014). All patients with axillary lymph node (ALN) metastases (n = 17, 100%) exhibited Clau 4 positivity (P = 0.021). The presence of PSMA expression observed to significantly increase the rate of ALN metastases (64.7% vs. 25%) (P = 0.035). Conclusion: Confirming PSMA expression with PET imaging would be significant as PSMA, a theranostic agent, may be a considerable potential agent for radionuclide treatment strategies, in addition to its additional diagnostic contribution to FDG, especially in patients with metastatic TNBC, which is an aggressive, heterogeneous disease.

Triple negative breast cancer (TNBC) is characterized by poor prognosis and limited response to standard treatments. Although ¹⁸F-FDG PET/CT is frequently used in staging and restaging, in some cases, it may be insufficient considering tumor heterogeneity. Prostate-specific membrane antigen (PSMA) has been reported to be overexpressed in many types of cancer due to tumor-associated neovascularization. ⁶⁸Ga-PSMA-11 PET/CT can be used to demonstrate radionuclide therapy option as well as detection of primary tumor and recurrence in TNBC. We present a 47-year-old woman with TNBC having recurrent brain metastasis with avid PSMA receptor activity versus low FDG uptake.

The aim of this study was to evaluate 18F-fluoro-2-deoxy-glucose (FDG) uptake patterns in primary tumors and metastatic lesions, and also to assess the diagnostic contribution of positron emission tomography/computed tomography (PET/CT) in the initial staging of gastric cancer (GC). The total number of 341 patients with GC were included in this study. All 18F-FDG PET/CT imagings were performed for initial staging. The maximum standardized uptake value (SUVmax) of primary tumor, obtained from 18F-FDG PET/CT imaging was compared between subtypes of GC. Mean SUVmax of 339 patients’ primary tumor was 12.9±8.6. The highest mean SUVmax was detected in patients with medullary subtype GC (17.8±9.9) while the lowest mean SUVmax (9.7±7.6) was seen in signet ring cell carcinoma (SRCC). The primary mean SUVmax was found statistically higher in adenocarcinoma (AC) group than SRCC group (p3 cm) in patients with AC (p=0.03). Primary tumor SUVmax was found statistically higher in regional lymph node (RLN) positive patients than in RLN negative patients in AC and SRCC groups (p<0.001 and p=0.012, respectivelly). Also, in patients with SRCC, SUVmax was significantly higher in the distant metastatic group than in the group without metastasis (p=0.025). Increased primary tumor SUVmax was associated with some of clinical parameters such as age and RLN metastasis in patients with AC. However, there was no relationship between distant metastatic state and primary tumor 18F-FDG uptake in AC. However, high SUVmax of primary tumor in SRCC was associated with regional and distant metastasis, and primary tumor 18F-FDG uptake may be a prognostic value for this subgroup.

The aim of this study was to examine the characteristics of patients admitted to our hospital with a diagnosis of breast cancer who reached pathological complete response after being operated following eight cycles of neoadjuvant chemotherapy. Between 2015-2020, patients with pathological complete response who were operated on after neoadjuvant chemotherapy and sent to our clinic for radiotherapy were evaluated. The median age of the patients was 51 years. The most common histological type was invasive ductal cancer. The number of pathological complete response patients was 74 (28%), and the number of non-pathological complete response patients was 188 (72%). Patients with pathological complete response had a smaller tumor diameter than the non-pathological complete response group (p=0.001). For pathological complete response, T1 stage, N1 stage, NG 3, Ki-67 >20%, negative estrogen receptor, negative progesterone receptor, positive Cerb-B2, and adding trastuzumab to chemotherapy were statistically significant (p<0.05). Before neoadjuvant chemotherapy, stage T1-T2 (p=0.036), LN0-1 (p=0.026), Cerb-B2 positivity (p=0.025), and an initial nuclear grade of three (p=0.001) were found to be the factors affecting pathological complete response. With neoadjuvant chemotherapy, the size of locally advanced tumors decreases, allowing breast conserving surgery. The neoadjuvant chemotherapy response can be used as an early indicator of the prognosis of patients with breast cancer. Today, neoadjuvant chemotherapy is also used for patients with early-stage, operable breast cancer because it has been shown in many studies that reaching pathological complete response is associated with positive long-term results. If we can identify patients who have reached pathological complete response before neoadjuvant chemotherapy, we think we can also determine a patient-specific treatment plan at the beginning of treatment.