The Predictive Value of Baseline Volumetric PET/CT Parameters on Treatment Response and Prognosis in Locally Advanced Rectal Cancer Treated with Neoadjuvant Chemoradiotherapy.

PURPOSE: To investigate the prognostic effects of baseline volumetric PET/CT parameters including the maximum standard uptake value (SUVmax), metabolic tumor volume (MTV), and tumor lesion glycolysis (TLG) on treatment response and prognosis in locally advanced rectal cancer (LARC) treated with neoadjuvant chemoradiotherapy (NACRT). METHODS: Between 2015 and 2018, 51 patients with LARC treated with NACRT followed by surgery were included in this retrospective study. Patients were divided into 2 groups by tumor regression grade (TRG) as follows: group I = TRG 1 (no detectable cancer cells) + TRG 2 (single cells and/or small groups of cancer cells) and group II = TRG3 (residual tumor outgrown by fibrosis) + TRG 4 (remarkable fibrosis outgrown by tumor cells) + TRG 5 (no fibrosis with extensive residual cancer). RESULTS: Of the 51 patients, 34 (66.7%) were male. The median age was 55 (range, 37-78) years. According to TRG status, 14 (27.4%) patients were in group I and 37 (72.6%) patients were in group II. The area under the curve (95% CI) was 0.749 (0.593-0.905) in the ROC curve plotted for MTV. The cut-off value for MTV was 12, with 70% sensitivity and 65% specificity. MTV was ≥ 12 in 32 (62.8%) patients. MTV and TLG values were significantly different between groups I and II, whereas there was no significant difference between the groups in terms of SUVmax values (p = 0.006, p = 0.033, and p = 0.673, respectively). The disease-free survival was not reached in patients with MTV < 12 vs. 20 months in those with MTV ≥ 12 (p = 0.323). In multivariate analysis, MTV (OR, 95% Cl, 5.00 [1.17-21.383]) was found to be the factor that affected pathological complete response. CONCLUSION: In LARC treated with NACRT, MTV prior to treatment can help predict the response to treatment.

Can 68Ga-PSMA PET/CT-derived prostate-specific membrane antigen expression parameters predict prostate-specific antigen response to enzalutamide treatment?

OBJECTIVE: In patients with metastatic castration-resistant prostate cancer (mCRPCa), enzalutamide is administered when docetaxel treatment fails. The purpose of the study was to evaluate the relationship between prostate-specific antigen (PSA) response and metabolic parameters obtained from 68Ga-PSMA PET/CT before treatment in this patient group. METHODS: From February 2018 to May 2020, 34 patients with mCRPCa were enrolled in this study. The association between PSA response (at least 50% decrease compared to the pretreatment value) and quantitative prostate-specific membrane antigen (PSMA) expression parameters such as SUVmax, SUVmean, PSMA-TV (PSMA receptor-expressing tumor volume) and TL-PSMA (total lesion PSMA receptor expression) were evaluated. RESULTS: Mean SUVmax, SUVmean, PSMA receptor-expressing tumor volume (PSMA-TV) and total lesion PSMA receptor expression (TL-PSMA) values were 33.66 ± 20.42; 8.82 ± 5.03; 319.85 ± 615.12 cm3; and 2894.76 ± 5195.13, respectively. In the posttreatment 12th week, 22 patients (64.7%) had PSA response, while 12 patients (35.3%) were nonresponders. In patients with PSA response, PSMA-TV values were significantly lower than nonresponders (78.37 ± 80.99 cm3 vs. 451.58 ± 734.61 cm3; P = 0.028). But there was no significant difference between responders and nonresponders in terms of age, ISUP grade, SUVmax, SUVmean, TL-PSMA, pretreatment PSA values, presence of local recurrence or metastases at any site. CONCLUSION: PSMA-TV values on 68Ga-PSMA PET/CT imaging before starting enzalutamide treatment following docetaxel failure can predict PSA response in patients with mCRPCa.

The relationship between pre-treatment 18F-FDG PET/CT metabolic data and treatment response in patients with cervix uteri cancer.

OBJECTIVE: To determine the risk group of patients with locally advanced squamous cell carcinoma of the uterine cervix that will resist to treatment before concomitant chemoradiotherapy and who will develop metastasis via fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) metabolic data. SUBJECTS AND METHODS: Fifty two patients with carcinoma of the uterine cervix who were treated in our clinic between 2015-2018 were evaluated. The presence of human papilloma virus (HPV) from the first paraffin blocks diagnosed in all patients has been tested withreal time polymerase chain reaction (PCR). All patients received brachytherapy after concomittant chemotherapy with external radiotherapy. The first 18F-FDG PET/CT and magnetic resonance images (MRI) images obtained for pretreatment staging and MRI after external radiotherapy were retrospectively reviewed. The patients who resisted concomittant chemoradiotherapy were tried and determined with pre-treatment 18F-FDG PET/CT metabolic data. RESULTS: The follow-up period of our patients with an average age of 53 years (42.5-60.75) was 53.5 months (42.5-60.75). Radiotherapy with a total median dose of 85 EqD2 (84-86) was delivered to all patients. The heterogeneity factor(HF) was found to be statistically significantly lower in patients in whom complete response was obtained after external radiotherapy in MRI (P=0.049). Any statistically significant difference was not found between groups of patients who did, and did not develop metastases as for primary tumor standardized uptake value (SUVmax, SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) values. In patients without metastasis, heterogeneity factor (HF) was found to be statistically significantly lower than those who developed metastasis (P=0.026). CONCLUSION: It is possible to predict poor prognostic patients with the help of HF, although we could not predict the resistant patients to treatment of primary tumor.

Correlations of the 68Ga-PSMA PET/CT derived primary prostate tumor PSMA expression parameters and metastatic patterns in patients with Gleason Score >7 prostate cancer.

OBJECTIVE: We aimed to investigate the correlations between the prostate specific membrane antigen (PSMA) expression parameters of the primary prostate tumor on gallium-68 (68Ga)-PSMA positron emission tomography/computed tomography (PET/CT) with metastatic patterns in patients with Gleason Score (GS) >7 prostate cancer (PCa). MATERIALS AND METHODS: This study included 55 PCa patients who had 68Ga-PSMA PET/CT performed for staging. According to metastatic pattern, patients were divided into 3 groups as non-metastatic (N0M0), those with isolated pelvic lymph node metastasis (N1M0) and with distant metastasis (M1). The correlations between the primary tumor PSMA expression parameters such as maximum standardize uptake value (SUVmax), SUVmean, PSMA-TV (PSMA receptor expressing tumour volume), and TL-PSMA (total lesion PSMA receptor expression) on 68Ga-PSMA PET/CT imaging and metastatic patterns were investigated. RESULTS: There were 21, 9 and 25 patients in the N0M0, N1M0 and M1 groups, respectively. The PSMA-TV and TL-PSMA values were significantly higher in the N1M0 and the M1 patient groups compared to the N0M0 group, but there was no significant difference between the N1M0 and M1 groups. The primary tumor SUVmax and SUVmean values were not significantly different between the three groups. The optimal PSMA-TV cut-off value for metastasis was >8.07cm3 (AUC 0.86) with sensitivity of 76.5% and specificity 85.7%. The optimal TL-PSMA cut-off value for metastasis was >93 (AUC 0.74) with sensitivity of 64%, and specificity 100%. CONCLUSION: The PSMA-TV and TL-PSMA values are strong markers for metastasis prediction in patients with GS >7 PCa but no other PSMA expression parameters can distinguish between N1M0 and M1 groups.

Relationship between pretreatment levels of serum Cyfra 21.1, CEA and PET metabolic parameters in NSCLC.

OBJECTIVE: No investigation has been conducted on the association between PET findings and serum Cyfra 21.1 and CEA levels in nonsmall cell lung cancers (NSCLC). The purpose of this study is to find out if the serum levels of Cyfra 21.1 and CEA are related to metabolic parameters by FDG PET in patients with NSCLC who had not received treatment. METHODS: Seventy-six NSCLC patients, who were admitted for initial staging by FDG PET/CT, were included in the study. Serum Cyfra 21.1 and CEA levels were assayed by enzyme-linked immunosorbent assay. FDG-PET images were analyzed with visual and quantitative methods. Standard uptake values (SUV), metabolic tumor volumes (MTV) and total lesion glycolysis were calculated for primary lesion (T) and whole-body lesions (primary and metastatic) (WB). RESULTS: Serum Cyfra 21.1 and CEA level was significantly higher in patients with locoregionally advanced disease (p < 0.05, p < 0.05, respectively) and metastatic disease (p < 0.01, p < 0.05, respectively) compared to those with localized disease. The serum ln-Cyfra-21.1 was significantly correlated with all volumetric tumor parameters (p < 0.001) and slightly with ln-SUVmean.WB (p < 0.05). There was no relationship between CEA levels and any PET metabolic parameters (p > 0.05). In multiple linear regression analysis incorporating ln-MTV.WB and ln-SUVmean.WB as independents, ln-MTV.WB correlated significantly and positively with ln-Cyfra-21.1 (ß = 0.744, p < 0.001), whereas ln-SUVmean.WB did not significantly predict ln-Cyfra-21.1 (ß = 0.019, p > 0.05). CONCLUSION: This study demonstrates the existence of a significant relationship between total tumor burden and the serum Cyfra 21.1 level in NSCLC patients who had not received treatment. However, it requires further confirmation in operated NSCLC patients.

Subcutaneous metastases of colorectal cancer detected with PET/CT.

Cutaneous and subcutaneous metastases of colorectal cancer is rare. The authors present a case of a 63-year-old man with colorectal carcinoma, who underwent preoperative staging with positron emission tomography/computed tomography (PET/CT). PET/CT demonstrated intensely increased uptake in the subcutaneous nodular lesion in the anterior surface of the right thigh. Histopathological examination of the excised subcutaneous nodular lesion revealed adenocarcinoma metastases.