Negative association between basal oxytocin and oxytocin changes after repetitive transcranial magnetic stimulation in patients with treatment-resistant depression.

Repetitive transcranial magnetic stimulation (rTMS) is a neuromodulator effective for treating depressive symptoms in patients with treatment-resistant depression (TRD). One of the multiple mechanisms for its antidepressant effects proposed is related to the hypothalamus. Oxytocin is a neuropeptide synthesized in the hypothalamus that affects human behavior and psychology, including social and affiliative behaviors, stress regulation, and fear and emotion processing. There have been no reports on the relationship between rTMS and oxytocin for the treatment of TRD. Therefore, we aimed to investigate changes in salivary oxytocin concentrations in patients with TRD before and after 6 weeks of rTMS treatment. A total of 28 patients with TRD who received rTMS at Saga University Hospital between August 2013 and August 2020 were included. Although rTMS treatment significantly improved 24-item Hamilton Depression Rating Scale scores, rTMS treatment did not change mean salivary oxytocin after 6 weeks of treatment in patients with TRD. Multiple regression analysis revealed that the change in salivary oxytocin levels after rTMS treatment was negatively associated with basal oxytocin levels before rTMS treatment, suggesting that rTMS treatment tends to decrease oxytocin levels in patients with depression with high basal oxytocin levels while increasing them in those with low basal levels. These findings suggest that rTMS treatment improved depressive symptoms through mechanisms other than the modulatory effect on oxytocin levels in patients with TRD, while there is room for further studies to confirm these findings using a larger patient sample size and/or a sham rTMS procedure.

Causes of death in patients operated for colorectal cancer.

BACKGROUND: Colorectal cancer remains the third leading cause of cancer-related mortality in the United States. This study evaluates the causes of death in patients operated on for colorectal cancer and their determinants. METHODS: An Instructional Review Board-approved database containing patients who underwent surgical resection for colorectal cancer from 2004 to 2018 (last followed up in December 2020) in a tertiary care institution. Data on the underlying cause of death was extracted from the Registry of Vital Records and Statistics in Massachusetts. RESULTS: A total of 576 deaths were recorded in the database, of which 290 (50.35%) patients died of colorectal cancer. Deaths from colorectal cancer gradually decreased over time, whereas deaths from other cancers increased, and deaths from cardiovascular diseases remained stable. Patients who died from colorectal cancer were younger, died earlier in the disease course, had fewer comorbidities, higher rates of stage IV disease, rectal cancer, neoadjuvant therapy, extramural vascular invasion, perineural invasion, R0 resection, and preserved mismatch repair protein status. On multivariate analysis, age (adjusted odds ratio for 10-year increase = 0.79, 95% confidence interval 0.65-0.95), American Society of Anesthesiologists score (adjusted odds ratio = 0.64, confidence interval 0.42-0.98), stage IV disease (adjusted odds ratio = 3.02, confidence interval 1.59-5.9), neoadjuvant therapy (adjusted odds ratio = 7.91, confidence interval 2.64-28.13), extramural vascular invasion (adjusted odds ratio = 2.3, confidence interval 1.36-3.91) & time from diagnosis to death (adjusted odds ratio = 0.76, confidence interval 0.68-0.83) predicted death due to colorectal cancer versus other causes, whereas tumor location, perineural invasion, R0 resection, and mismatch repair protein status did not. CONCLUSION: There is a declining trend of deaths from colorectal cancer, presumably reflecting advances in colorectal cancer management strategies and better screening over time. However, younger patients disproportionately contribute to death due to colorectal cancer and need aggressive screening and management strategies.

Development and multicentre validation of the FLEX score: personalised preoperative surgical risk prediction using attention-based ICD-10 and Current Procedural Terminology set embeddings.

BACKGROUND: Preoperative knowledge of surgical risks can improve perioperative care and patient outcomes. However, assessments requiring clinician examination of patients or manual chart review can be too burdensome for routine use. METHODS: We conducted a multicentre retrospective study of 243 479 adult noncardiac surgical patients at four hospitals within the Mass General Brigham (MGB) system in the USA. We developed a machine learning method using routinely collected coding and patient characteristics data from the electronic health record which predicts 30-day mortality, 30-day readmission, discharge to long-term care, and hospital length of stay. RESULTS: Our method, the Flexible Surgical Set Embedding (FLEX) score, achieved state-of-the-art performance to identify comorbidities that significantly contribute to the risk of each adverse outcome. The contributions of comorbidities are weighted based on patient-specific context, yielding personalised risk predictions. Understanding the significant drivers of risk of adverse outcomes for each patient can inform clinicians of potential targets for intervention. CONCLUSIONS: FLEX utilises information from a wider range of medical diagnostic and procedural codes than previously possible and can adapt to different coding practices to accurately predict adverse postoperative outcomes.

Trends and Determinants of Location of Death Due to Colorectal Cancer in the United States : A Nationwide Study.

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer-related mortality in the United States (US); however, there are limited data on location of death in patients who die from CRC. We examined the trends in location of death and determinants in patients dying from CRC in the US. METHODS: We utilized the Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database to extract nationwide data on underlying cause of death as CRC. A multinomial logistic regression was performed to assess associations between clinico-sociodemographic characteristics and location of death. RESULTS: There were 850,750 deaths due to CRC from 2003 to 2019. There was a gradual decrease in deaths in hospital, nursing home, or outpatient facility/emergency department over time and an increase in deaths at home and in hospice. Relative to White decedents, Black, Asian, and American Indian/Alaska Native decedents were less likely to die at home and in hospice compared with hospitals. Individuals with lower educational status also had a lower risk of dying at home or in hospice compared with in hospitals. CONCLUSIONS: The gradual shift in location of death of patients who die of CRC from institutionalized settings to home and hospice is a promising trend and reflects the prioritization of patient goals for end-of-life care by healthcare providers. However, there are existing sociodemographic disparities in access to deaths at home and in hospice, which emphasizes the need for policy interventions to reduce health inequity in end-of-life care for CRC.

Incidence of Secondary Cancers After Neoadjuvant Therapy for Locally Advanced Rectal Cancer.

INTRODUCTION: Whether neoadjuvant chemoradiation for locally advanced rectal cancer (LARC) induces secondary cancers is controversial. This retrospective cohort study describes the incidence of secondary cancers in LARC patients. METHODS: We compared 364 LARC patients who received conventional (50.4 Gy) or short course neoadjuvant radiation (25 Gy x 5 fractions) followed by resection to 142 patients with surgically resected rectal cancer who did not receive radiation at a single institution from 2004 to 2018. Secondary cancer was defined as any nonmetastatic noncolorectal malignancy diagnosed via biopsy or definitive imaging criteria at least 6 mo after completion of neoadjuvant therapy or after resection in the comparison group. RESULTS: Among the neoadjuvant radiation group (364 patients, 40% female, age 61 ± 13 y), 32 patients developed 34 (9.3%) secondary cancers. Three cases involved a pelvic organ. Among the comparison group (142 patients, 39% female, age 64 ± 15 y), 15 patients (10.6%) developed a secondary cancer. Five cases involved pelvic organs. Secondary cancer incidence did not differ between groups. Latency period to secondary cancer diagnosis was 6.7 ± 4.3 y. Patients who received radiation underwent longer median follow-up (6.8 versus 4.5 y, P < 0.01) and were significantly less likely to develop a pelvic organ cancer (odds ratio 0.18; 95% confidence interval, 0.04-0.83; P = 0.02). No genetic mutations or cancer syndromes were identified among patients with secondary cancers. CONCLUSIONS: Neoadjuvant chemoradiation is not associated with increased secondary cancer risk in LARC patients and may have a local protective effect on pelvic organs, especially prostate. Ongoing follow-up is critical to continue risk assessment.

Metformin Does not Affect Outcomes in Patients With Locally Advanced Rectal Cancer Treated With Neoadjuvant Therapy and Resection.

INTRODUCTION: There is emerging evidence that metformin may have a protective effect in patients with cancer. However, its current evidence in locally advanced rectal cancer (LARC) is inconclusive. We aim to assess the effect of metformin on long-term outcomes in patients with LARC who received neoadjuvant therapy and surgical resection. METHODS: A retrospective review of 324 patients with nonmetastatic LARC who received neoadjuvant therapy and major surgical resection from 2004 to 2018. There were 27 patients who received metformin before surgery and 297 patients who did not receive metformin. RESULTS: Metformin users were associated with a significantly higher age, BMI, ASA score, and 30-day readmissions (P < .05). There was no difference in overall survival (OS, P = .18) or disease-free survival (DFS, P = .33) between the two groups. On Cox regression, metformin intake did not predict OS (HR 0.85, 95% CI 0.4-1.77) when controlled for age (HR 1.04, 1.02-1.06), sex (HR 1.13, 0.69-1.85), BMI (HR 0.97, 0.92-1.02), ASA score (HR: 1.7, 1.06-2.73), TNT (HR 0.31, 0.1-0.92), pathological Stage III disease (HR 2.55, 1.51-4.32), extramural vascular invasion (EMVI) (HR 3.06, 1.7-5.5), and adjuvant therapy (HR 0.1, 0.04-0.27 for <25 months OS and HR 0.3, 0.15-0.59 for ≥25 months). Disease-free survival showed a similar trend with no significant effect of metformin (HR 0.77, 0.39-1.52) when controlled for age, sex, BMI, ASA, TNT, Stage III disease, EMVI, and adjuvant therapy. CONCLUSION: Metformin does not affect long-term survival in LARC treated with neoadjuvant therapy followed by surgical resection. Studies with larger sample sizes are needed to validate the findings further.

Stratification of Stage II Colon Cancer Using Recurrence Prediction Value: A Multi-institutional International Retrospective Study.

OBJECTIVE: To create a recurrence prediction value (RPV) of high-risk factor and identify the patients with high risk of cancer recurrence. SUMMARY BACKGROUND DATA: There are several high-risk factors known to lead to poor outcomes. Weighting each high-risk factor based on their association with increased risk of cancer recurrence can provide a more precise understanding of risk of recurrence. METHODS: We performed a multi-institutional international retrospective analysis of patients with Stage II colon cancer patients who underwent surgery from 2010 to 2020. Patient data from a multi-institutional database were used as the Training data, and data from a completely separate international database from two countries were used as the Validation data. The primary endpoint was recurrence-free survival (RFS). RESULTS: A total of 739 patients were included from Training data. To validate the feasibility of RPV, 467 patients were included from Validation data. Training data patients were divided into RPV low (n = 564) and RPV high (n = 175). Multivariate analysis revealed that risk of recurrence was significantly higher in the RPV high than the RPV low (Hazard ratio (HR) 2.628; 95% confidence interval (CI) 1.887-3.660; P < 0.001). Validation data patients were divided into two groups (RPV low, n = 420) and RPV high (n = 47). Multivariate analysis revealed that risk of recurrence was significantly higher in the RPV high than the RPV low (HR 3.053; 95% CI 1.962-4.750; P < 0.001). CONCLUSIONS: RPV can identify Stage II colon cancer patients with high risk of cancer recurrence world-wide.

Colitis-Associated Colorectal Cancer Survival is Comparable to Sporadic Cases after Surgery: a Matched-Pair Analysis.

BACKGROUND: Inflammatory bowel disease (IBD) confers an increased lifetime risk of colorectal cancer (CRC). The pathogenesis of colitis-associated CRC is considered distinct from sporadic CRC, but existing is mixed on long-term oncologic outcomes. This study aims to compare clinicopathological characteristics and survival between colitis-associated and sporadic CRC. METHODS: Data was retrospectively extracted and analyzed from a single institutional database of patients with surgically resected CRC between 2004 and 2015. Patients with IBD were identified as having colitis-associated CRC. The remainder were classified as sporadic CRC. Propensity score matching was performed. Univariate and survival analyses were carried out to estimate the differences between the two groups. RESULTS: Of 2275 patients included in this analysis, 65 carried a diagnosis of IBD (2.9%, 33 Crohn's disease, 29 ulcerative colitis, 3 indeterminate colitis). Average age at CRC diagnosis was 62 years for colitis-associated CRC and 65 for sporadic CRC. The final propensity score matched cohort consisted of 65 colitis-associated and 130 sporadic CRC cases. Patients with colitis-associated CRC were more likely to undergo total proctocolectomy (p < 0.01) and had higher incidence of locoregional recurrence (p = 0.026) compared to sporadic CRC patients. There were no significant differences in time to recurrence, tumor grade, extramural vascular invasion, perineural invasion, or rate of R0 resections. Overall survival and disease-free survival did not differ between groups. On multiple Cox regression, IBD diagnosis was not a significant predictor of survival. CONCLUSIONS: Patients with colitis-associated CRC who undergo surgical resection have comparable overall and disease-free survival to patients with sporadic CRC.

Patient Factors Affecting Inpatient Mortality Following Colorectal Cancer Resection.

BACKGROUND: Our objective is to identify factors for inpatient death in patients undergoing resection for colorectal cancer (CRC). STUDY DESIGN: Unmatched 1:3 case-control study of surgically resected CRC at a tertiary care institution between 2004 and 2018. Variables for multivariate analysis were selected using tetrachoric correlation followed by a least absolute shrinkage and selection operator (LASSO) penalized regression model. RESULTS: A total of 140 patients were included (N = 35 patients who died inpatient, N = 105 patients who did not die). Patients who died were older, had higher Charlson Comorbidity Index (CCI), higher rates of preoperative anemia, hypoalbuminemia, emergency surgeries, blood transfusion, postoperative vasopressor requirement, anastomotic leak, and postoperative ICU admission than patients who underwent surgical resection without inpatient mortality. Anemia (aOR = 8.62, 1.44-91.58), emergency admission (aOR = 5.71, 1.46-24.36), and ICU admission (aOR 45.51, 8.31-448.4) significantly predicted inpatient mortality when controlled for CCI and hypoalbuminemia. CONCLUSIONS: Surprisingly, it appears that pre-existing anemia and perioperative factors are more important in predicting inpatient mortality of patients undergoing CRC surgery than baseline comorbidity or nutritional status.

Salivary 3-methoxy-4-hydroxyphenylglycol and MRI-based volume change of the precuneus in community-dwelling elderly people.

BACKGROUND: The noradrenergic systems in the brain maintain cognitive functions including attention/concentration and establishment of long-term memory. In addition, hypofunction of noradrenergic systems is supposed to be involved in the pathophysiology of Alzheimer's disease. In this study, we tried to examine the possible associations of concentrations of basal salivary 3-methoxy-4-hydroxyphenylglycol (sMHPG), a major metabolite of noradrenaline, and brain volume changes during 4 years in elderly people living in a rural community. METHODS: The survey was conducted twice in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged 65 years and older. We collected data from 226 residents. Measurements of sMHPG and brain MRIs were collected at Time 1 (2005-2007). Follow-up brain MRIs were taken at Time 2 (2009-2011). A total of 70 participants (18 men, mean age 71.9 ± 4.8 years; 52 women, mean age 72.0 ± 4.3 years) completed this survey. Concentrations of sMHPG at baseline were divided into two groups using the mean value (12.83 ng/ml). We compared the brain volumes between groups with higher and lower sMHPG concentrations over time using voxel-based morphometry implemented with statistical parametric mapping. RESULTS: In participants with higher sMHPG concentrations at baseline, brain volumes including right precuneus were significantly larger 4 years after baseline than those with lower sMHPG concentrations at baseline. No interaction between sMHPG concentration and MRI acquisition interval was found. CONCLUSION: Our results suggest that higher sMHPG concentrations in elderly people might be associated with maintenance of brain volume, especially in brain regions closely related to cognitive function.

Serum soluble triggering receptor expressed on myeloid cells-2 was not altered by rTMS in patients with treatment-resistant depression.

AIM: Repetitive transcranial magnetic stimulation (rTMS) is one of the most effective and minimally invasive treatments for treatment-resistant depression (TRD). However, the mechanism underlying the therapeutic effects of rTMS in patients with TRD remains unclear. In recent years, the pathogenesis of depression has been closely associated with chronic inflammation and microglia are believed to play an important role in chronic inflammation. Triggering receptor expressed on myeloid cells-2 (TREM2) plays an important role in microglial neuroinflammatory regulation. In this study, we investigated the changes in peripheral soluble TREM2 (sTREM2) before and after rTMS treatment in patients with TRD. METHODS: Twenty-six patients with TRD were enrolled in this frequency (10 Hz) rTMS study. Depressive symptoms, cognitive function, and serum sTREM2 concentrations were measured at baseline and the end of the 6-week rTMS treatment. RESULTS: This study showed that rTMS ameliorated depressive symptoms and partially improved cognitive dysfunction in TRD. However, rTMS treatment did not alter serum sTREM2 levels. CONCLUSIONS: This is the first sTREM2 study in patients with TRD who underwent rTMS treatment. These results suggest that serum sTREM2 may not be relevant for the mechanism underlying the therapeutic effect of rTMS in patients with TRD. Future studies should confirm the present findings using a larger patient sample and a sham rTMS procedure, as well as CSF sTREM2. Furthermore, a longitudinal study should be conducted to clarify the effects of rTMS on sTREM2 levels.

Serum oxytocin correlated with later logical memory in older Japanese women: A 7-year follow-up study.

Objectives: This study aimed to investigate the longitudinal relationship between serum oxytocin and logical memory among older adults in rural Japan and clarify sex differences in this relationship. Measurements: The first survey was conducted from October 2009 to March 2011 (Time 1) and the second from November 2016 to September 2017 (Time 2). The final analysis for Time 1 included 385 participants (median age 75 years, interquartile range [IQR] 70-81 years) and that for Time 2 included 76 participants (median age 80 years, IQR 76-83 years). We assessed cognition, logical memory, and living conditions, and measured serum oxytocin levels. Logical memory was evaluated using the Wechsler Memory Scale-Revised Logical Memory II delayed recall part A (LM II-DR). Serum oxytocin was measured using the enzyme immunoassay method. Results: The median (IQR) oxytocin level among men (n = 20) was 34 (16-78) pg/mL at Time 1 and 53 (28-140) pg/mL at Time 2. The median (IQR) oxytocin level among women (n = 56) was 117 (35-412) pg/mL at Time 1 and 76 (32-145) pg/mL at Time 2. The median oxytocin level among women at Time 2 was significantly lower than that at Time 1 (p = 0.004). The multivariate analysis showed that for women, LM II-DR score at Time 2 was positively associated with oxytocin level at Time 1 (p = 0.042) and negatively associated with age (p = 0.02). Conclusions: Our study suggests that maintaining high oxytocin levels in older women may prevent age-related decline in logical memory.

The time Interval Between the End of Radiotherapy and Surgery Does Not Affect Outcomes in Rectal Cancer.

INTRODUCTION: The ideal time interval between the completion of chemoradiotherapy and subsequent surgical resection of advanced stage rectal tumors is highly debated. Our aim is to study the effect of the time interval between the completion of chemoradiotherapy and surgical resection on postoperative and oncologic outcomes in rectal cancer. METHODS: Patients who underwent neoadjuvant chemoradiotherapy for resected locally advanced rectal tumors between 2004 and 2015 were included in this analysis. The time interval was calculated from the date of radiation completion to date of surgery. Patients were split into 2 groups based on the time interval (<8 weeks and >8 weeks). Postoperative outcomes (anastomotic leak, pathologic complete response (pCR), and readmission) and survival were assessed with multivariable logistic regression and Cox regression models while adjusting for relevant confounders. RESULTS: 200 patients (62% male) underwent resection with a median time interval of 8 weeks from completion of radiotherapy. On multivariable logistic regression, there was no significant increase in odds between time interval to surgery and anastomotic leak (aOR = .8 [.27-2.7], P = .8), pCR (aOR = 1.2[.58-2.6] P = .6), or readmission (aOR = 1.02, 95% CI:0.49-2.24, P = .9). Time interval to surgery was not an independent prognostic factor for overall (HR = 1.04 CI = .4-2.65, P = .9) and disease-free survival (HR = 1.2 CI = .5-2.9, P = .6). CONCLUSION: The time interval between neoadjuvant radiotherapy completion and surgical resection does not affect anastomotic leak rate, achievement of pCR, or overall and disease-free survival in patients with rectal cancer. Extended periods of time to surgical resection are relatively safe.

Association of age with outcomes in locally advanced rectal cancer treated with neoadjuvant therapy followed by surgery.

INTRODUCTION: We aimed to assess the association of age with outcomes in patients with Locally Advanced Rectal Cancer (LARC) who received neoadjuvant therapy followed by major surgery. METHODS: Retrospective review of 328 patients with LARC, N = 99 < 70 years (younger) versus N = 229 ≥ 70 years (elderly) from 2004 to 2018. RESULTS: Elderly patients had a higher American Society of Anesthesiologists (ASA) score, Charlson Comorbidity Index (CCI), length of stay and 30-day readmissions (p < 0.05). They also had worse overall survival (OS) & disease-free survival (DFS) (p < 0.001), but similar disease-specific survival (DSS) compared to younger group. Age was not associated with hazard of death (HR 1.01, 0.98-1.03). Rather, CCI (HR 1.29, 1.01-1.5), extramural vascular invasion (HR 4.98, 2.84-8.74), and adjuvant therapy (0.37, 0.21-0.64) were significantly associated with the hazard of death; when controlled for stage, tumor distance from anal verge, and neoadjuvant completion. CONCLUSION: Comorbidities and lower rates of adjuvant therapy, and not chronologic age, are associated with poor OS of elderly patients with LARC treated with neoadjuvant therapy and major surgery.

Molecular Basis of Extramural Vascular Invasion (EMVI) in Colorectal Carcinoma.

BACKGROUND: Extramural vascular invasion (EMVI) is a known poor prognostic factor in colorectal carcinoma; however, its molecular basis has not been defined. This study aimed to assess the expression of molecular markers in EMVI positive colorectal carcinoma to understand their tumor microenvironment. METHODS: Immunohistochemistry was performed on tissue microarrays of surgically resected colorectal cancer specimens for immunological markers, and BRAFV600E mutation (and on the tissue blocks for mismatch repair proteins). Automated quantification was used for CD8, LAG3, FOXP3, PU1, and CD163, and manual quantification was used for PDL1, HLA I markers (beta-2 microglobulin, HC10), and HLA II. The Wilcoxon rank-sum test was used to compare EMVI positive and negative tumors. A logistic regression model was fitted to assess the predictive effect of biomarkers on EMVI. RESULTS: There were 340 EMVI positive and 678 EMVI negative chemo naïve tumors. PDL1 was barely expressed on tumor cells (median 0) in the entire cohort. We found a significantly lower expression of CD8, LAG3, FOXP3, PU1 cells, PDL1 positive macrophages, and beta-2 microglobulin on tumor cells in the EMVI positive subset (p ≤ 0.001). There was no association of BRAFV600E or deficient mismatch repair proteins (dMMR) with EMVI. PU1 (OR 0.8, 0.7-0.9) and low PDL1 (OR 1.6, 1.1-2.3) independently predicted EMVI on multivariate logistic regression among all biomarkers examined. CONCLUSION: There is a generalized blunting of immune response in EMVI positive colorectal carcinoma, which may contribute to a worse prognosis. Tumor-associated macrophages seem to play the most significant role in determining EMVI.

Delayed Operative Management in Complicated Acute Appendicitis-Is Avoiding Extended Resection Worth the Wait ? Results from a Global Cohort Study.

BACKGROUND: The optimal management of complicated acute appendicitis remains undefined. According to current guidelines, a trial of non-operative management with delayed appendectomy may be associated with better outcomes for patients, including a reduced rate of extended resection appendectomy. METHODS: We conducted an analysis of the American College of Surgeons National Surgical Quality Improvement program to analyze the outcomes of hemodynamically stable patients presenting with complicated (abscess, perforation, or both) appendicitis submitted to early (less than 24 h) or delayed (24 h or more) operative management. RESULTS: Delayed operative management was associated with a significant reduction of the rate of extended resection appendectomy (RR: 2.15, 95% CI: 1.59 - 2.81, p < 0.001). Delayed operative management was associated with a non-significant trend towards reduced mortality (RR: 2.17; 95% CI: 0.98-2.85, p = 0.05). Delayed operative management was also associated with a significant decrease in total operative time and a significant reduction in the rate of postoperative abscess. There was no association between delayed intervention and medical related morbidity (RR: 1.01; 95% CI 0.91-1.11, p 0.811). However, delayed operative management was associated with a significant increase in total length of stay (coefficient 1.10; 95% CI: 1.02 to 1.18, p < 0.001). CONCLUSION: Delayed operative management may be associated with a reduction in the need of extended resection appendectomy, shorter operative time, and a trend towards reduced mortality. On the other hand, it may also be associated with an increased length of in-hospital stay and short-term morbidity.

Tumour genotypes account for survival differences in right- and left-sided colon cancers.

AIM: We sought to identify genetic differences between right- and left-sided colon cancers and using these differences explain lower survival in right-sided cancers. METHOD: A retrospective review of patients diagnosed with colon cancer was performed using The Cancer Genome Atlas, a cancer genetics registry with patient and tumour data from 20 North American institutions. The primary outcome was 5-year overall survival. Predictors for survival were identified using directed acyclic graphs and Cox proportional hazards models. RESULTS: A total of 206 right- and 214 left-sided colon cancer patients with 84 recorded deaths were identified. The frequency of mutated alleles differed significantly in 12 of 25 genes between right- and left-sided tumours. Right-sided tumours had worse survival with a hazard ratio of 1.71 (95% confidence interval 1.10-2.64, P = 0.017). The total effect of the genetic loci on survival showed five genes had a sizeable effect on survival: DNAH5, MUC16, NEB, SMAD4, and USH2A. Lasso-penalized Cox regression selected 13 variables for the highest-performing model, which included cancer stage, positive resection margin, and mutated alleles at nine genes: MUC16, USH2A, SMAD4, SYNE1, FLG, NEB, TTN, OBSCN, and DNAH5. Post-selection inference demonstrated that mutations in MUC16 (P = 0.01) and DNAH5 (P = 0.02) were particularly predictive of 5-year overall survival. CONCLUSIONS: Our study showed that genetic mutations may explain survival differences between tumour sites. Further studies on larger patient populations may identify other genes, which could form the foundation for more precise prognostication and treatment decisions beyond current rudimentary TNM staging.