Undetectable circulating tumor DNA confirms the inability of pseudomyxoma peritonei to systemic dissemination

The study of circulating tumor DNA (ctDNA) plays a pivotal role in advancing precision oncology, providing valuable information for individualized patient care and contributing to the ongoing effort to improve cancer diagnosis, treatment, and management. However, its applicability in pseudomyxoma peritonei (PMP) remains unexplored. In this multicenter retrospective study involving 21 PMP patients, we investigated ctDNA presence in peripheral blood using three distinct methodologies. Despite mucinous tumor tissues exhibiting KRAS and GNAS mutations, ctDNA for these mutations was undetectable in blood samples. In this pilot study, circulating tumor DNA was not detected in blood when the tumor harbored mutations of known significance. In the future, a study with a larger sample size is needed to confirm these findings and to determine whether ctDNA could identify patients at risk for early recurrence and/or systemic metastases.

A Proposal for Modification of the PSOGI Classification According to the Ki-67 Proliferation Index in Pseudomyxoma Peritonei

BACKGROUND

Pseudomyxoma peritonei (PMP) is a rare malignancy, classified according to the Peritoneal Surface Oncology Group International (PSOGI) classification, whose response to treatment remains highly heterogeneous within the high-grade (HG) category. Molecular profiling of PMP cases might help to better categorize patients and predict treatment responses.

METHODS

We studied the Ki-67 proliferation rate and P53 overexpression in tissue samples from our historical cohort of HG-PMP patients. We established as cut-off levels the third quartile of each marker to perform univariate and multivariate Cox regression survival analyses. According to these results, the HG-PMP category was divided into subcategories and a new survival analysis was performed.

RESULTS

A total of 90/117 patients with PMP undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) were selected for secondary analysis. The survival analysis of the HG-PMP category for preoperative variables showed that a proliferation index defined by Ki-67 >15% is a bad prognostic factor, with a hazard ratio (HR) of 3.20 (95% confidence interval [CI] 1.24-8.25). Accordingly, the HG-PMP group was divided using the Ki-67 15% cut-off. The new PSOGI/Ki-67 variable was an independent prognostic factor for overall survival (OS), with an HR of 3.74 (95% CI 1.88-7.47), and disease-free survival (DFS), with an HR of 4.184 (95% CI 1.79-9.75). The estimated 5-year OS rate was 100%, 70% and 24% for the LG-PMP, HG-PMP ≤15% and HG-PMP >15% groups, respectively (p = 0.0001), while the 5-year DFS rate was 90%, 44% and 0%, respectively (p = 0.0001).

CONCLUSION

Division of the HG-PMP category of the PSOGI classification, according to the Ki-67 proliferation index, provides two well-defined subcategories, with significant differences in terms of OS and DFS, and hence high prognostic value.

From the Ronnett to the PSOGI Classification System for Pseudomyxoma Peritonei: A Validation Study

BACKGROUND

Several classifications have been used for pseudomyxoma peritonei (PMP), and among these, the Ronnett classification is the most commonly used. However, a new consensual Peritoneal Surface Oncology Group International (PSOGI) classification has recently been proposed. Nonetheless, to date, the ability of the PSOGI classification to predict survival based on its different disease histologic categories has not been validated.

METHODS

This study enrolled 117 patients with PMP who had undergone cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) between 1997 and 2020. Cox proportional hazards regression models and time-dependent curve receiver operating characteristic (ROC) analyses were used to assess the predictive capacity of both classification systems for the overall survival (OS) and disease-free survival (DFS) of these patients.

RESULTS

Significant differences in the 5-year OS rate were found for the different histologic grades according to each of the classifications. The completeness of cytoreduction score (CCS) was identified as a factor that predicted patient OS prognosis (p = 0.006). According to the time-dependent ROC curves at the "100" time point, adjusted by the CCS and DFS, the capacity to predict OS was optimal and achieved an area under the curve (AUC) of about 69% for OS and approximately 62% for DFS.

CONCLUSIONS

Both the Ronnett and PSOGI classifications were able to predict survival optimally for this patient cohort. However, when the classifications were adjusted by the CCS, the predictive availability for OS was better with the PSOGI classification than with the Ronnett classification.

Biochemical biomarkers of pollution in the clam Chamaelea gallina from south-Spanish littoral

Fourteen biochemical pollution biomarkers were analyzed in the clam Chamaelea gallina sampled at seven South-Spanish littoral sites at different times in 1999. They included enzymes that regenerate reduced nicotinamide adenine dinucleotide phosphate (NADPH) or maintain the cytosol-reduced (glucose-6-P- and isocitrate dehydrogenases, glutathione reductase), that decompose reactive oxygen species (catalase, superoxide dismutase, glutathione peroxidase), or detoxify glutathione-reactive electrophiles (soluble and microsomal glutathione transferases, glyoxalases II and I). The levels of reduced glutathione, malondialdehyde, and metallothionein and the glutathione redox status were also determined. Clams from Huelva sites with higher contaminant loads and metallothionein levels showed higher antioxidant and glutathione-related activities and a decreased glutathione level, lower malondialdehyde content, and a less oxidized glutathione status. This suggests that clams chronically exposed to contaminants released by Huelva and Guadalquivir Estuaries are better protected from oxidative stress than reference animals. Most biomarkers showed six-month cyclicity with up to threefold amplitudes, further supporting the inverse relationship between antioxidant defenses and oxidative damages. Thus the lower antioxidant defenses in June fit to maximum oxidative damages, whereas the high antioxidant defenses found in March and September through October agree with lower lipid damages and less oxidized glutathione status. The effect of environmental or endogenous factors on this cyclic response is discussed.