Ranking as a Procedure for Selecting a Replacement Variable in the Score Predicting the Survival of Patients Treated with Curative Intent for Colorectal Liver Metastases

Background and Objectives: The issue of a missing variable precludes the external validation of many prognostic models. For example, the Liverpool score predicts the survival of patients undergoing surgical therapy for colorectal liver metastases, but it includes the neutrophil-lymphocyte ratio, which cannot be measured retrospectively. Materials and Methods: We aimed to find the most appropriate replacement for the neutrophil-lymphocyte ratio. Survival analysis was performed on data representing 632 liver resections for colorectal liver metastases from 2000 to 2020. Variables associated with the Liverpool score, C-reactive protein, albumins, and fibrinogen were ranked. The rankings were performed in four ways: The first two were based on the Kaplan-Meier method (log-rank statistics and the definite integral IS between two survival curves). The next method of ranking was based on univariate and multivariate Cox regression analyses. Results: The ranks were as follows: the radicality of liver resection (rank 1), lymph node infiltration of primary colorectal cancer (rank 2), elevated C-reactive protein (rank 3), the American Society of Anesthesiologists Classification grade (rank 4), the right-sidedness of primary colorectal cancer (rank 5), the multiplicity of colorectal liver metastases (rank 6), the size of colorectal liver metastases (rank 7), albumins (rank 8), and fibrinogen (rank 9). Conclusions: The ranking methodologies resulted in almost the same ranking order of the variables. Elevated C-reactive protein was ranked highly and can be considered a relevant replacement for the neutrophil-lymphocyte ratio in the Liverpool score. These methods are suitable for ranking variables in similar models for medical research.

Evaluation of the Iwate Model for Predicting the Difficulty of Laparoscopic Liver Resection: Does Tumor Size Matter?

BACKGROUND

This study aimed to externally validate the Iwate scoring model and its prognostic value for predicting the risks of intra- and postoperative complications of laparoscopic liver resection.

METHODS

Consecutive patients who underwent pure laparoscopic liver resection between 2008 and 2019 at a single tertiary center were included. The Iwate scores were calculated according to the original proposition (four difficulty levels based on six indices). Intra- and postoperative complications were compared across difficulty levels. Fitting the obtained data to the cumulative density function of the Weibull distribution and a linear function provided the mean risk curves for intra- and postoperative complications, respectively.

RESULTS

The difficulty levels of 142 laparoscopic liver resections were scored as low, intermediate, advanced, and expert level in 41 (28.9%), 53 (37.3%), 32 (22.5%), and 16 (11.3%) patients, respectively. Intraoperative complications were detected in 26 (18.3%) patients and its rates (2.4%, 7.5%, 34.3%, and 62.5%) increased gradually with statistically significant values among difficulty levels (P ˂ 0.001). Major postoperative complications occurred in 21 (14.8%) patients and its rates (4.8%, 5.6%, 28.1%, 43.7%; P ˂ 0.001) showed the same trend as for intraoperative complications. Then, the mean risk curves of both complications were obtained. Due to outliers, a new threshold for a tumor size index was proposed at 38 mm. The repeated analysis showed improved results.

CONCLUSIONS

The Iwate scoring model predicts the probability of complications across difficulty levels. Our proposed tumor size threshold (38 mm) improves the quality of the prediction. The model is upgraded by a probability of complications for every difficulty score.

The external validation of a difficulty scoring system for predicting the risk of intraoperative complications during laparoscopic liver resection

BACKGROUND

This study aimed to externally validate and upgrade the recent difficulty scoring system (DSS) proposed by Halls et al. to predict intraoperative complications (IOC) during laparoscopic liver resection (LLR).

METHODS

The DSS was validated in a cohort of 128 consecutive patients undergoing pure LLRs between 2008 and 2019 at a single tertiary referral center. The validated DSS includes four difficulty levels based on five risk factors (neoadjuvant chemotherapy, previous open liver resection, lesion type, lesion size and classification of resection). As established by the validated DSS, IOC was defined as excessive blood loss (> 775 mL), conversion to an open approach and unintentional damage to surrounding structures. Additionally, intra- and postoperative outcomes were compared according to the difficulty levels with usual statistic methods. The same five risk factors were used for validation done by linear and advanced nonlinear (artificial neural network) models. The study was supported by mathematical computations to obtain a mean risk curve predicting the probability of IOC for every difficulty score.

RESULTS

The difficulty level of LLR was rated as low, moderate, high and extremely high in 36 (28.1%), 63 (49.2%), 27 (21.1%) and 2 (1.6%) patients, respectively. IOC was present in 23 (17.9%) patients. Blood loss of >775 mL occurred in 8 (6.2%) patients. Conversion to open approach was required in 18 (14.0%) patients. No patients suffered from unintentional damage to surrounding structures. Rates of IOC (0, 9.5, 55.5 and 100%) increased gradually with statistically significant value among difficulty levels (P < 0.001). The relations between the difficulty level, need for transfusion, operative time, hepatic pedicle clamping, and major postoperative morbidity were statistically significant (P < 0.05). Linear and nonlinear validation models showed a strong correlation (correlation coefficients 0.914 and 0.948, respectively) with the validated DSS. The Weibull cumulative distribution function was used for predicting the mean risk probability curve of IOC.

CONCLUSION

This external validation proved this DSS based on patient's, tumor and surgical factors enables us to estimate the risk of intra- and postoperative complications. A surgeon should be aware of an increased risk of complications before starting with more complex procedures.

Fusion of the RBP56 and CHN genes in extraskeletal myxoid chondrosarcomas with translocation t(9;17)(q22;q11)

Although most extraskeletal myxoid chondrosarcomas (EMC) are cytogenetically characterized by the translocation t(9;22)(q22;q12), another subset has recently been identified carrying a t(9;17)(q22;q11). Whereas the t(9;22) is known to result in fusion of the CHN (TEC) gene from 9q22 with the EWS gene from 22q12, creating a chimeric EWS/CHN, the genes involved in the t(9;17) of EMC are unknown. We examined two EMC with t(9;17)(q22;q11) and found that the CHN gene was recombined with the RBP56 gene from 17q11 to generate a chimeric RBP56/CHN. RBP56 has not previously been shown to be involved in tumorigenesis but it encodes a putative RNA-binding protein similar to the EWS and FUS (TLS) proteins known to play a pathogenetic role in several sarcomas. The presence of the RBP56/CHN chimeric gene in EMC with t(9;17)(q22;q11) shows that the N-terminal parts of EWS and RBP56 have similar oncogenic potential making them pathogenetically equivalent in oncoproteins arising from fusions with certain transcription factors.

Characterization of TFG in mus musculus and Caenorhabditis elegans

TFG was discovered as a fusion partner of NTRK1 in human papillary thyroid carcinoma. We assembled the mouse TFG cDNA from EST sequences and 5' end RACE product, identified full coding length TFG EST clones in pig (c17b07) and Schistosoma mansoni (SMNAS62), and analyzed the genomic structure of TFG in Caenorhabditis elegans (Y63D3A). The protein sequences of mouse, pig, and S. mansoni TFG are highly homologous to human TFG. The C. elegans sequence has diverged, but its predicted secondary structure is remarkably conserved. Human, mouse, and C. elegans TFG contain a putative trimeric N-terminal coiled-coil domain, glycosylation, myristylation, and phosphorylation sites, and SH2- and SH3-binding motifs. The SH2-binding motif is absent in C. elegans TFG. The expression of TFG does not vary among 7, 11, 15, and 19 day mouse embryonal stages. In situ hybridization with a TFG probe in 10, 5-day whole mouse embryos showed preferential staining of the limb buds, branchial arches, nasal processes, and brain, and weak staining of the primitive spinal cord and dorsal root ganglia.

Expression analysis and chromosomal mapping of a novel human gene, APRIL, encoding an acidic protein rich in leucines

Clone 120041 was selected from the EST database for sequence similarity to DEK and SET proteins rearranged in leukemias. The ends of the cDNA were isolated by RACE technique. The assembled cDNA encodes an LRR-containing protein of 251 amino acids designated APRIL (acidic protein rich in leucines). APRIL has high similarity to human pp32, also named PHAPI (bovine I[PP2A]1), and to rat LANP, respectively. APRIL shows tissue-specific expression as shown by Northern blot analysis. It was localized to 15q25 by FISH.

Characterization and chromosomal mapping of the human TFG gene involved in thyroid carcinoma

Homology searches in the Expressed Sequence Tag Database were performed using SPYGQ-rich regions as query sequences to find genes encoding protein regions similar to the N-terminal parts of the sarcoma-associated EWS and FUS proteins. Clone 22911 (T74973), encoding a SPYGQ-rich region in its 5' end, and several other clones that overlapped 22911 were selected. The combined data made it possible to assemble a full-length cDNA sequence. This cDNA sequence is 1677 bp, containing an initiation codon ATG, an open reading frame of 400 amino acids, a poly(A) signal, and a poly(A) tail. We found 100% identity between the 5' part of the consensus sequence and the 598-bp-long sequence named TFG. The TFG sequence is fused to the 3' end of NTRK1, generating the TRK-T3 fusion transcript found in papillary thyroid carcinoma. The cDNA therefore represents the full-length transcript of the TFG gene. TFG was localized to 3q11-q12 by fluorescence in situ hybridization. The 3' and the 5' ends of the TFG cDNA probe hybridized to a 2.2-kb band on Northern blot filters in all tissues examined.

Expression patterns of the human sarcoma-associated genes FUS and EWS and the genomic structure of FUS

FUS (TLS) was first identified as the 5'-part of a fusion gene with CHOP (GADD153, DDIT3) in myxoid liposarcomas with t(12; 16)(q13; p11). Homologies were found with the EWS oncogene, which is rearranged in Ewing sarcomas and other neoplasias. The genomic structure of FUS shows extensive similarities with that of EWS, but the exon/intron structures differ in the 5' parts, and overall FUS is smaller than EWS. Exon 3 of FUS corresponds to exons 3 and 4 in EWS. FUS exons 4-6 correspond to EWS exons 5-8. Exons 7 to 15 of FUS are very similar to those in EWS, although the EWS exons are larger than the corresponding FUS exons. FUS and EWS were expressed in all tissues investigated. The transcripts were stable within the 160-min half-life experiments. No or little variation in FUS or EWS expression was seen when resting lymphocytes were activated. These observations indicate that FUS and EWS belong to the housekeeping type of genes. This view is supported by the presence of the housekeeping gene type of promoter region in both genes.