Development and validation of a nomogram to predict the risk factors of major complications after radical rectal cancer surgery

Purpose

The aim of this study was to establish a validated nomogram to predict risk factors for major post-operative complications in patients with rectal cancer (RC) by analyzing the factors contributing to major post-operative complications in RC patients.

Methods

We retrospectively collected baseline and surgical information on patients who underwent RC surgery between December 2012 and December 2022 at a single-center teaching hospital. The entire cohort was randomly divided into two subsets (60% of the data for development, 40% for validation). Independent risk factors for major post-operative complications were identified using multivariate logistic regression analyses, and predictive models were developed. Area under the curve (AUC) was calculated using receiver operating characteristic curve (ROC) to assess predictive probability, calibration curves were plotted to compare the predicted probability of the nomogram with the actual probability, and the clinical efficacy of the nomogram was assessed using decision curve analysis (DCA).

Results

Our study included 3151 patients who underwent radical surgery for RC, including 1892 in the development set and 1259 in the validation set. Forty (2.1%) patients in the development set and 26 (2.1%) patients in the validation set experienced major post-operative complications. Through multivariate logistic regression analysis, age (p<0.01, OR=1.044, 95% CI=1.016-1.074), pre-operative albumin (p<0.01, OR=0.913, 95% CI=0.866-0.964), and open surgery (p<0.01, OR=2.461, 95% CI=1.284-4.761) were identified as independent risk factors for major post-operative complications in RC, and a nomogram prediction model was established. The AUC of the ROC plot for the development set was 0.7161 (95% Cl=0.6397-0.7924), and the AUC of the ROC plot for the validation set was 0.7191 (95% CI=0.6182-0.8199). The predicted probabilities in the calibration curves were highly consistent with the actual probabilities, which indicated that the prediction model had good predictive ability. The DCA also confirmed the good clinical performance of the nomogram.

Conclusion

In this study, a validated nomogram containing three predictors was created to identify risk factors for major complications after radical RC surgery. Due to its accuracy and convenience, it could contribute to personalized management of patients in the perioperative period.

Short Communication: Genetic linkage map of Cucurbita maxima with molecular and morphological markers

Cucurbita maxima is one of the most widely cultivated vegetables in China and exhibits distinct morphological characteristics. In this study, genetic linkage analysis with 57 simple-sequence repeats, 21 amplified fragment length polymorphisms, 3 random-amplified polymorphic DNA, and one morphological marker revealed 20 genetic linkage groups of C. maxima covering a genetic distance of 991.5 cM with an average of 12.1 cM between adjacent markers. Genetic linkage analysis identified the simple-sequence repeat marker 'PU078072' 5.9 cM away from the locus 'Rc', which controls rind color. The genetic map in the present study will be useful for better mapping, tagging, and cloning of quantitative trait loci/gene(s) affecting economically important traits and for breeding new varieties of C. maxima through marker-assisted selection.

First Report of Phytophthora Blight of Lily Caused by Phytophthora nicotianae in China

Lily (Lilium spp.) is an economically important cut flower in China. In August 2009, 30 to 40% of plants of lily cv. Siberia in a greenhouse for cut flower production in Yunnan, China were severely diseased. Infected plants developed water-soaked lesions and soft rot on the base of stems and leaves near the soil surface. As the disease progressed, stems bent and plants collapsed. Soft rot symptoms were observed on some bulbs and roots of severely diseased plants. Small, diseased tissue fragments (approximately 3 mm) were surface disinfected with 0.5% NaOCl and then plated to Phytophthora selective medium (10% V8 juice agar) (4). Inoculated dishes were incubated at 25°C in the dark. After 5 days, white colonies with abundant aerial mycelia developed from all plated tissue samples. The fungus had aseptate hyphae. Sporangia were papillate, both caducous and noncaducous, and the shape ranged from ovoid to spherical. The dimensions of sporangia were 30 to 62 × 21 to 46 μm. On the basis of morphological features, isolates were identified as Phytophthora nicotianae Breda de Haan. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS1/ITS4 and sequenced. BLAST analysis of the 835-bp fragment showed a 99% homology with the sequence of P. nicotianae AY833527. The nucleotide sequence has been assigned GenBank No. GU299778. PCR amplification of genomic DNAs using the P. nicotianae-specific primer pair ITS3-PNIC1 generated a 455-bp sequence (3). The result further confirmed the identity of P. nicotianae. Pathogenicity tests were conducted in the greenhouse on lily cv. Siberia grown in pots. Ten 3-month-old plantlets were inoculated by watering the wounded stem bases and soil surface with 30 ml of zoospore suspensions (10⁵ spores per ml). Five uninoculated plantlets were used as controls. All plantlets were covered with plastic bags and incubated at room temperature (22 to 26°C) for 48 h. Inoculated plants developed initial symptoms of slight chlorosis and wilting of lower leaves. Within a 3-week period, all plants died due to soft rot of stem bases and leaves. The pathogen was reisolated from inoculated plants but not from control plants that were symptomless. P. nicotianae has been reported as the causal agent of Phytophthora blight on lily in Korea, Japan, and Hungary (1,2). To our knowledge, this is the first report of Phytophthora blight of lily in China. References: (1) J. Bakonyi et al. Plant Pathol. 50:795, 2001. (2) H. J. Jee and W. G. Kim. Plant Pathol. J. 14:452, 1998. (3) P. W. Tooley et al. Appl. Environ. Microbiol. 63:1467, 1997. (4) X. B. Zheng. Phytophthora and Its Research Technology. Beijing. China Agriculture Press, Beijing, 1997.

First Report of Southern Blight Caused by Sclerotium rolfsii on Lily in China

Lily (Lilium spp.) is an economically important cut flower cultivated in China. The soilborne fungus, Sclerotium rolfsii, is a major pathogen on many plants. During July 2005, severe basal stem rot and bulb rot symptoms were observed on an oriental lily cultivar (Sorbonne) in some commercial fields in northern Kunming (China). Disease incidence ranged from 20 to 30% across fields. Leaves of infected plants were chlorotic initially. As the disease progressed, stems and bulbs rotted and plants wilted. In the presence of abundant moisture, a white mycelium occurred on infected tissues. White or light-to-dark brown sclerotia (1 to 3 mm in diameter) developed from mycelium. Fungal isolates from infected bulbs grown on potato dextrose agar (PDA) produced white mycelia and 1- to 2-mm diameter dark brown sclerotia. Sclerotia were nearly round with smooth surfaces and distributed over the entire colony. Isolates were identified as S. rolfsii on the basis of mycelial characteristics and color, size, and distribution of sclerotia. Pathogenicity was tested in the greenhouse on oriental lily cv. Sorbonne grown in pots (1 plant per pot, five replicates). Inoculum that consisted of 1 g per pot of wheat kernels infested with mycelium and sclerotia was placed at the base of each inoculated plant. Five noninoculated plants served as controls. The inoculation trial was repeated once. After inoculation, all plants were covered with a polyethylene bag for 72 h and kept at temperatures ranging between 25 and 27°C. Inoculated plants developed symptoms of leaf yellowing within 12 days, soon followed by the appearance of white mycelium and sclerotia, and then eventually wilted. Control plants remained symptomless. S. rolfsii was reisolated from inoculated plants. To our knowledge, this is the first report of southern blight caused by S. rolfsii on lily in China. Infection of lily bulbs by S. rolfsii may cause losses in production fields in China, and the presence of infected bulbs may also interfere with bulb shipment.