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Currently, the use of assisted reproductive technology (ART) is increasing. Because of the poor prognosis of retinopathy of prematurity (ROP), the association between ART and the ROP has been explored in several studies, but the result was still inconclusive. Conducting a meta-analysis, we evaluated the risk of ROP in relation to the ART. Subgroup analysis as well as groups with different embryo numbers and different ROP stages was further analyzed. The PubMed, Embase, and Cochrane Library databases were searched for studies recording data about both the use of ART and ROP occurrence simultaneously. Odds ratios (ORs) and 95% confidence interval (95%CI) were calculated to analyze the association by using random- or fixed-effect models based on heterogeneity test. In total 15 observational studies containing 10392 ART cases and 39474 spontaneous conception cases were included. Results showed that there was a significant association between the use of ART and ROP occurrence in the offspring (OR = 1.34, 95% CI: 1.05 to 1.73, P = 0.02). With subgroup analysis, we found that the influence actually came from a subgroup of ART, the in vitro fertilization (IVF). Moreover, there was a significant association between ART and ROP in singletons. Though insignificant, the ORs were larger than 1 in the analysis between ART and stage 1 and 2 ROP. But ART showed significant association with stage 3 ROP. Our study preliminarily indicated that the use of IVF was associated with higher risk of ROP occurrence. And ART is more likely to result in severe ROP and ROP in singletons. Further specific, high-quality studies with large sample size are still needed to draw more precise conclusion. [ABSTRACT FROM AUTHOR]

Background. Preclinical and epidemiological data suggest that metformin might have antineoplastic properties against colon cancer (CC). However, the effect of metformin use on patient survival in stage III CC after curative resection is unknown. The survival outcomes were comparable regardless of the duration of metformin use. Patients and Methods. Before randomization to FOLFOX (folinic acid, 5-fluorouracil, oxaliplatin) with or without cetuximab, 1,958 patients with stage III CC enrolled in the N0147 study completed a questionnaire with information on diabetes mellitus (DM) and metformin use. Cox models were used to assess the association between metformin use and disease-free survival (DFS), overall survival (OS), and the time to recurrence (TTR), adjusting for clinical and/or pathological factors. Results. Of the 1,958 patients, 1,691 (86%) reported no history of DM, 115 reported DM with metformin use (6%), and 152 reported DM without metformin use (8%). The adjuvant treatment arms were pooled, because metformin use showed homogeneous effects on outcomes across the two arms. Among the patients with DM (n = 267), DFS (adjusted hazard ratio [aHR], 0.90; 95% confidence interval [CI], 0.59-1.35; p = .60), OS (aHR, 0.99; 95% CI, 0.65-1.49; p = .95), and TTR (aHR, 0.87; 95% CI, 0.56-1.35; p = .53) were not different for the metformin users compared with the nonusers after adjusting for tumor and patient factors. The survival outcomes were comparable regardless of the duration of metformin use (>1,1-5,6-10, ≥11 years) before randomization (ptrend = .64 for DFS, ptrend = .84 for OS, and ptrend = .87 for TTR). No interaction effects were observed between metformin use and KRAS, BRAF mutation status, tumor site,T/N stage, gender, or age. Conclusions. Patients with stage III CC undergoing adjuvant chemotherapy who used metformin before the diagnosis of CC experienced DFS, OS, and TTR similar to those for non-DM patients and DM patients without metformin use. [ABSTRACT FROM AUTHOR]

Background: Recently, pretreatment monocyte counts and the lymphocyte/monocyte ratio (LMR) have been proven to be significantly associated with the clinical outcomes of several types of cancer. In this study, we analyzed the prognostic significance of the LMR in stage Ib1-IIa cervical cancer patients who underwent a radical operation. Methods: A total of 485 patients with stage Ib1-IIa cervical cancer were included in this retrospective study. We evaluated the prognostic values of the absolute lymphocyte count, absolute monocyte count, and LMR by applying receiver operating characteristic curves. Kaplan-Meier curves and multivariate Cox proportional analyses were used to determine the recurrence-free survival (RFS) and overall survival (OS). Results: The area under the curve was 0.640 for the RFS and 0.647 for the OS using the LMR. In the univariate analysis, an elevated preoperative LMR was significantly associated with an increased RFS (hazard ratio [HR], 0.373; 95% confidence interval [CI]: 0.247-0.563; P<0.001), and this result remained significant in the multivariate analysis (HR, 0.439; 95% CI: 0.279-0.693; P<0.001). In the univariate analysis, an elevated LMR was also significantly associated with an increased OS (HR, 0.381; 95% CI: 0.233-0.622; P<0.001), and the significance persisted in the multivariate analysis (HR, 0.417; 95% CI: 0.244-0.714; P=0.001). Conclusion: A decreased pretreatment LMR is associated with a poor prognosis in stage Ib1-IIa cervical cancer patients who undergo a radical operation. A prospective study is warranted for further validation of our findings. [ABSTRACT FROM AUTHOR]

A well-designed pilot study can advance science by providing essential preliminary data to support or motivate further research, refine study logistics, and demonstrate proof of concept. Often, the outcomes of such studies can be quantified by a success/failure dichotomy. For example, a novel compound may show activation of a neural pathway, or it may not. When an intervention's efficacy is quantified using a dichotomous outcome, probability mass functions can be enumerated to determine the probability that the observed result from a pilot study supports further evaluation of the intervention since there is only a finite, and often small, number of sample configurations possible. The purpose of this research was to determine the probability of an 'efficacy signal' for pilot studies using one- and two-sample pilot study designs. Efficacy signal was defined as the probability of observing a more favorable response proportion relative to a historical control (one-sample setting) or to a concurrent control (two-sample setting). An enumeration study (exact simulation) was conducted to calculate the efficacy signal probability. One-sample study designs yielded higher probability of determining an efficacy signal than the two-sample setting; however, sampling variation must be accounted for. A 68% score confidence interval is recommended for this purpose. [ABSTRACT FROM AUTHOR]

Survival of patients with stage III colon cancer varies widely according to T-N sub-stages. Estimating the benefit of each therapeutic option in each T-N subgroup may provide more accurate information helping doctors and patients in the complex shared decision-making process surrounding adjuvant therapy. The outcomes data of 12,834 patients with stage III colon cancer enrolled in the IDEA trial served as our database. Patients were categorised in 16 sub-stages, based on T-N categories. We created a meta-regression model to predict the expected 5-year DFS within each T-N sub-stage. We then evaluated the efficacy of each therapeutic option in every sub-stage, working backward by subtraction, using an average of the HRs reported in pertinent trial publications as a conversion factor. Large differences in 5-year DFS rate were observed among the subgroups, ranging from 89% (T1N1a) to 31% (T4N2b) in the overall population. The contribution to the outcome of each therapeutic option in this setting varied widely across sub-stages. According to our model, patients with T1N1a cancers have a projected 5-year DFS of 79.6% with surgery alone. Adjuvant fluoropyrimidine alone results in 5.6% absolute DFS gain; an additional 2.3% and 0.8% gain is seen with oxaliplatin for 3 and 6 months, respectively. Patients with T4N2b cancers show a 13.9% 5-year DFS with surgery alone, and an 11.2%, 6.4%, 2.5% increase with the aforementioned adjuvant options, respectively. The resulting overlay bar graph gives patients and doctors the projected relative benefit of each treatment option and may substantially help the shared decision-making process, although caution must be exercised in using this model due to the significant variance of the estimates. • Survival of patients with stage III colon cancer varies according to T-N sub-stages. • Average risk and benefit of adjuvant therapy is not applicable to individual patients • We showed that T1N1a has 89% 5-year DFS and that T4N2b has 31% 5-year DFS. • The contribution of each therapeutic option varied widely across sub-stages. • The resulting overlay bar graph shows the absolute benefit of each treatment option. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Objectives: To determine the prevalence of self-reported 1-year injury history and examine its association with preparticipation evaluation components aimed at predicting future injury risk (PPE-IP) among preprofessional ballet and contemporary dancers. Design: Cross-sectional study. Setting: Preprofessional ballet school, university contemporary dance program. Participants: Full-time preprofessional ballet and contemporary dancers. Assessment of Risk Factors: Preparticipation evaluation consisted of the Athletic Coping Skills Inventory-28, body mass index, total bone mineral density, ankle range of motion, active standing turnout, lumbopelvic control, unipedal dynamic balance, and Y-Balance test. Main Outcome Measure: Self-reported 1-year history of dance-related medical attention and/or time-loss injury. Results: A total of 155 ballet [n = 90, 80 females, median age 15 years (range 11-19)] and contemporary [n = 65, 63 females, median age 20 years (range 17-30)] dancers participated. Forty-six percent (95% confidence interval (CI), 38.4-54.6) reported a 1-year injury history. Self-reported injury history was not associated with any PPE-IP, however, an influence of age and psychological coping skills on the relationship between 1-year injury history and PPE-IP was identified. Multivariable analyses revealed that prevalence of 1-year injury history did not differ by age [referent group <15 years; 15-18 years: odds ratio (OR) 0.80 (95% CI, 0.35-1.79); >18 years: OR 0.69 (95% CI, 0.30-1.56)], or level of psychological coping skills [OR 1.35 (95% CI, 0.61-2.94)]. Conclusions: The prevalence of self-reported 1-year injury history among preprofessional ballet and contemporary dancers is high. Although measures of PPE-IP did not differ based on injury history, it is important that age and psychological coping skills are considered in future dance injury prevention and prediction research. Level of Evidence: Level 3 evidence. [ABSTRACT FROM AUTHOR]

Previous studies suggest a possible sex-specific response to bevacizumab in metastatic colorectal carcinoma (mCRC), showing a benefit in males, while the effect in females is less significant. Data from 3369 patients with mCRC enrolled on four first-line randomised trials testing chemotherapy with or without bevacizumab (2000–2007) were pooled. Association between sex and progression-free survival and overall survival (OS) was evaluated by stratified Cox regression model, adjusted for potential confounders. Predictive value was evaluated by interaction effect between sex and treatment. In a pre-planned secondary analysis, analyses were stratified using an age cut point of 60 years to evaluate the possible role of menopausal-related effects. Bevacizumab was associated with an improved median OS in males and females, with a 2.3- and 0.6-months benefit, respectively. Stratified by age, bevacizumab resulted in improved OS in males at both age categories. In females at or above the age of 60 (n = 731), bevacizumab resulted in improved OS. However, in females below the age of 60 (n = 634), OS benefit did not reach statistical significance (adjusted hazard ratio = 0.94, 95% confidence interval 0.74–1.20). Our results confirmed the OS benefit from the addition of bevacizumab to first-line chemotherapy in mCRC in both sexes. Among females, the benefit was less than 1 month. For females under the age of 60, there was no survival benefit. These findings could be used to relieve financial toxicity or be redistributed within healthcare systems for other health-related purposes. • Bevacizumab was associated with an improved median overall survival (OS) of 1.8 months. • For females, median OS benefit from bevacizumab was <1 month. • For females under the age of 60, there was no OS benefit. • Sex- and age-specific reporting is essential in future trials testing bevacizumab. [ABSTRACT FROM AUTHOR]

Diabetes mellitus (DM) has been associated with increased colorectal cancer (CRC) risk and worse prognosis in metastatic CRC patients. In this large, pooled analysis of non-metastatic colon cancer (CC) patients, we investigated the impact of DM and metformin treatment on recurrence and survival. A patient-level pooled analysis from three randomised adjuvant trials was performed. All patients had resection with curative intent of stage II or III CC and were treated with standard adjuvant fluoropyrimidine and oxaliplatin (±cetuximab). We investigated the impact of DM and metformin treatment on time to recurrence (TTR) and overall survival (OS). Of 5922 CC patients who had a median follow-up of 6.8 years, 621 patients (10.5%) had DM at CC diagnosis. Of those with DM, 327 patients (52.7%) were defined as metformin users and 294 patients (47.3%) as non-metformin users. CC patients with DM had a significantly shorter TTR (adjHR: 1.21; 95% CI, 1.03–1.42; p = 0.017) and OS (adjHR: 1.29; 95% CI, 1.09–1.52; p = 0.003) compared to non-diabetic CC patients. Diabetic CC patients not receiving metformin had a significantly worse TTR (adjHR: 1.28; 95% CI, 1.02–1.60; p = 0.032) and OS (adjHR: 1.41; 95% CI, 1.13–1.77; p = 0.003) as compared to non-diabetic patients. These worse outcomes were not significant in metformin users (TTR: adjHR: 1.16; 95% CI, 0.94–1.43; p = 0.168; OS: adjHR: 1.19; 95% CI, 0.95–1.48, p = 0.127). CC patients with DM had not only a significantly worse survival but also TTR. Furthermore, our data suggest that metformin may attenuate the detrimental effect of DM on CC patient outcomes. • DM was associated with impaired survival and time -to -recurrence in early CC patients. • Both outcomes were the shortest in diabetic patients without metformin treatment. • These findings seemed especially relevant in patients with KRAS and BRAF-wt tumours. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) affects many older adults. We investigated the efficacy and safety of adding anti-epidermal growth factor receptor (EGFR) agents to doublet chemotherapy (DC) in older patients. Patients with RAS wild-type (WT) metastatic CRC (mCRC) receiving first-line DC + anti-EGFR (n = 1191) or DC alone (n = 729) from seven trials in the Aide de Recherche en Cancerologie Digestive database were included. The prognostic and predictive effects of age were investigated. Progression-free and overall survival (OS) were evaluated between age groups (≥70 vs <70) for DC + anti-EGFR. In addition, outcomes were compared between DC+/-anti-EGFR within age groups in three trials with a DC alone arm. Subsequently, the same analysis was conducted for left-sided tumours. Adverse events grade ≥3 (G3+) were compared between age groups. Older (vs younger) patients receiving DC + anti-EGFR had similar progression-free survival (PFS) (8.7 vs 10.3 months; hazard ratio (HR) = 1.20 [0.96–1.49];p = 0.107) but inferior OS (21.3 vs 26.3; HR = 1.36 [1.08–1.72];p = 0.011). DC + anti-EGFR (vs DC alone) improved OS (23.9 vs 20.3; HR = 0.82 [0.70–0.95];p = 0.008) and PFS (11.2 vs 8.9; HR = 0.70 [0.60–0.82];p < 0.001) in younger but not older patients: OS (24.7 vs 17.6; HR [95% confidence interval {CI}] = 0.77 [0.58–1.04];p = 0.092) and PFS (9.1 vs 8.7; HR [95% CI] = 0.85[0.63–1.15];p = 0.287). In left-sided 'only' tumours, the following outcomes for older (vs younger) patients were observed. For DC + anti-EGFR, PFS 9 versus 11.2 months; HR1.10 (95% CI 0.83–1.46); p = 0.52, OS 25.6 vs 30.3 HR 1.32 (95% CI 0.97–1.79), p = 0.086. For DC + anti-EGFR (vs DC alone), PFS and OS for younger patients were 11.9 vs 9.2 months HR 0.60 (95% CI 0.47–0.78) p < 0.001 and 24.1 versus 23.3 months HR 0.84 (95% CI 0.67–1.04), respectively. For older patients, PFS and OS were 13.1 versus 8.5 months, HR 0.51 (95% CI, 0.28–0.93), P = 0.027 and 26.3 versus 16.5 months HR 0.49 (95% CI, 0.28–0.85), respectively. There was no significant difference in toxicity among different age groups. Older (vs younger) patients with mCRC RAS WT patients had comparable toxicity and efficacy with the addition of anti-EGFR agents to chemotherapy. • Older patients with colorectal cancer are under-represented in clinical trials. • Investigated effect of age in patients treated with chemotherapy and anti-EGFR agents. • No significant difference in the risk for G3+ toxicity between over and under 70s. • Comparable efficacy outcomes for younger and older patients receiving anti-EGFR agents. [ABSTRACT FROM AUTHOR]

While genome-wide association studies (GWAS) have identified germline variants influencing the risk of developing colorectal cancer (CRC), there has been limited examination of the possible role of inherited variation as a determinant of patient outcome. We performed a GWAS for overall survival (OS) in 1926 patients with advanced CRC from the COIN and COIN-B clinical trials. For single nucleotide polymorphisms (SNPs) showing an association with OS (P < 1.0 × 10−5), we conducted sensitivity analyses based on the time from diagnosis to death and sought independent replications in 5675 patients from the Study of Colorectal Cancer in Scotland (SOCCS) and 16,964 patients from the International Survival Analysis in Colorectal cancer Consortium (ISACC). We analysed the Human Protein Atlas to determine if ERBB4 expression was associated with survival in 438 patients with colon adenocarcinomas. The most significant SNP associated with OS was rs79612564 in ERBB4 (hazard ratio [HR] = 1.24, 95% confidence interval [CI] = 1.16–1.32, P = 1.9 × 10−7). SNPs at 17 loci had suggestive associations for OS and all had similar effects on the time from diagnosis to death. No lead SNPs were independently replicated in the meta-analysis of all patients from SOCCS and ISACC. However, rs79612564 was significant in stage-IV patients from SOCCS (P = 2.1 × 10−2) but not ISACC (P = 0.89) and SOCCS combined with COIN and COIN-B attained genome-wide significance (P = 1.7 × 10−8). Patients with high ERBB4 expression in their colon adenocarcinomas had worse survival (HR = 1.50, 95% CI = 1.1–1.9, P = 4.6 × 10−2). Genetic and expression data support a potential role for rs79612564 in the receptor tyrosine kinase ERBB4 as a predictive biomarker of survival. • A genome-wide search for biomarkers of survival in 1926 patients with advanced CRC. • Seventeen potential prognostic variants with replication of rs79612564 in ERBB4. • A median decrease in life expectancy of ∼40 days per allele carried. • Patients with high ERBB4 expression in colon tumours had worse survival. • Potential use for rs79612564 and/or ERBB4 as a prognostic biomarker. [ABSTRACT FROM AUTHOR]

Immune checkpoint inhibitors (ICIs) appeared active in single-arm trials for patients with chemoresistant metastatic colorectal cancer (mCRC) harboring microsatellite instability (MSI). Given the paucity of randomised controlled trials (RCTs) in this setting, we evaluated the effect size of ICIs using intra-patients comparison and ARCAD database as historical controls. Individual-patient data from NIPICOL and CheckMate 142 phase II trials that evaluated a combination of ICIs for MSI mCRC patients (N = 176) and from five non-ICI mCRC historical RCTs in second-line or latter (N = 4026) were analyzed. Firstly, promising of ICIs was identified using intra-patient comparison based on growth modulation index (GMI) defined the ratio of progression-free survivals (PFS) on ICIs and previous line of therapy. Survival outcomes of ICIs-treated patients were then compared with those matched non-ICIs treated from ARCAD database historical RCTs. Among ICIs-treated patients, median PFS on ICIs was 32.66 (range 0.10–74.25) versus 4.07 months (range 0.7–49.87) on prior therapy, resulting on median GMI of 4.97 (range 0.07–59.51; hazard-ratio (HR)= 0.16 (95 %CI=0.11–0.22, P < 0.001)). Compared to matched non-ICI patients, in third-line, median overall survival (OS) was not reached with ICIs versus 3.52 months with placebo (HR=0.20, 95 %CI=0.10–0.41, P < 0.001), and 6.51 months with active drugs (HR=0.30, 95 %CI=0.15–0.60, P = 0.001). In second-line, median OS was not reached with ICIs versus 11.7 months with chemotherapy+placebo (HR=0.12, 95 %CI=0.07–0.22, P < 0.001), and 16.3 months with chemotherapy+targeted therapy (HR=0.10, 95 %CI=0.05–0.19, P < 0.001). ICIs demonstrates high effect size for MSI mCRC patients in second-line and later. This work might be useful as an example of methodology to avoid RCTs when benefit from experimental therapy is likely to be high. • Immune checkpoint inhibitors (ICIs) are highly promising for MSI mCRC patients. • Reimbursement of promising drugs might be hampered in case of non-randomised trials. • IPD-based meta-analysis can be used to build synthetic control arms (SACs). • High effect size of ICIs was found using both patients as their own control and non-randomised trials based on SACs. [ABSTRACT FROM AUTHOR]

Stratification of patients with stage III colon cancer into low (T 1-3 N 1) and high (T 4 and/or N 2) risk groups is used to guide the duration of adjuvant chemotherapy. We determined the relative contribution of clinical and molecular features to survival by risk group. Stage III colon cancer (N = 5337) patients from two adjuvant trials of FOLFOX ± cetuximab [N0147 (Alliance), PETACC-8] were risk grouped, then subgrouped by clinical features and molecular variables [ KRAS and BRAF/ mismatch repair (MMR) combined variable]. Distributions of disease-free survival (DFS), overall survival (OS), and survival after recurrence (SAR) were estimated. In multivariable Cox models, backward elimination was performed for analysis of candidate predictors of outcomes. Relative contributions of model-selected variables to outcomes by risk group were calculated using χ2. Among low risk tumours, mutant KRAS and male gender were significantly associated with poorer OS multivariately. In high risk tumours, significantly poorer OS was observed for right sidedness and for mutant KRAS and BRAF V600E /pMMR, subgroups. Specifically, BRAF V600E /pMMR (OS: HR = 1.75; 95% CI: 1.36–2.24; P adj <.0001) and right- versus left-sidedness were associated with significantly poorer DFS, OS (HR = 1.56; 95% CI: 1.31–1.83; P adj <.0001), and SAR (HR = 1.64; 95% CI: 1.37–1.95; P adj <.0001). Poor prognosis of mutant KRAS for DFS and OS was similar among risk groups. BRAF /MMR and sidedness were associated with poorer SAR in both low and high risk tumours. Age, gender, and KRAS were the top three relative contributors to DFS and OS among low risk tumours; sidedness ranked first for DFS and OS, and second to BRAF /MMR for SAR among high risk tumours. Sidedness and BRAF/ MMR contributed the most to survival outcomes among high risk tumours and should be interpreted in the context of risk group. • Sidedness, KRAS, and BRAFV600E are related with poorer survival in high and low risk tumours. • Sidedness and BRAF /MMR contributed the most to survival among high risk tumours. • Age, gender, and KRAS were the top relative contributors to survival in low risk tumours. [ABSTRACT FROM AUTHOR]

Only one-half of deficient mismatch repair (d-MMR) metastatic colorectal cancers (mCRC) demonstrate durable responses to immune checkpoint inhibitors (ICIs). Given preclinical data indicating that liver metastases sequester activated CD8+ T cells from systemic circulation, we examined clinical outcome by metastatic site. In a retrospective cohort of patients with d-MMR mCRCs treated at multiple centers in France (n = 66), we sought to validate data from a U.S. cohort, and performed pooled analysis (n = 104). All patients received first-line ICI monotherapy. Metastatic site was analyzed in relationship to tumor response (RECIST version 1.1), and with progression-free survival (PFS) by multivariable stratified Cox regression after adjustment for covariates. Objective responses were achieved in 38/66 (58%) of patients in the validation cohort. Best tumor response included 13 (20%) complete responses (CR), 25 (38%) partial responses (PR), 16 (25%) stable disease, and 11 (17%) progressive disease (PD). One-year and 5-year PFS rates were 73% and 67%, respectively; 18 (27%) patients progressed during immunotherapy. Best tumor response was attenuated in patients with liver metastasis (P = 0.03). Presence of liver metastasis, but not other sites, was associated with significantly poorer PFS after adjustment for covariates (HR adj 2.82; 95%CI, 1.08–7.39; P adj =0.03). In a pooled analysis, liver metastasis remained significantly and independently associated with poorer PFS (HR adj 3.18; 95%CI, 1.52–6.67; P adj =0.002) and with attenuated tumor best response (P = 0.01). Metastasis to the liver, but not other sites, was validated as an independent factor associated with poorer response and survival after ICI treatment in d-MMR mCRCs. These data underscore the need for novel therapeutic strategies in these patients. ● Patients were treated with an immune checkpoint inhibitor as first-line therapy. ● An independent patient cohort and pooled analysis of d-MMR mCRCs was performed. ● Liver metastasis was associated with poorer survival after ICI. ● Other sites of disease spread were not associated with poorer survival after ICI. ● Liver metastasis was validated as associated with shorter survival after ICI. [ABSTRACT FROM AUTHOR]

Abstract Purpose Patients with left-sided colon tumours have better survival and respond differently to biologics compared with patients with right-sided tumours. Left-sided colon tumours and rectal cancers are often grouped together. Herein, we examined the clinicopathological differences and outcomes between left-sided colon and rectal cancers. Patients and methods Data from 2879 metastatic colorectal cancer patients enrolled on six first-line clinical trials during 2004–2010 were pooled. Patients were included if the primary tumour origin was clearly defined. Progression-free survival (PFS) and overall survival (OS) were compared in the two groups after adjusting for patient and tumour characteristics, metastatic sites and the first-line regimen. Results In total, 1374 patients with metastatic left-sided colon cancer and 1505 patients with metastatic rectal cancers were evaluated. Left-sided colon cancer patients were more likely to be female (40.1% versus 32.6%; P < 0.0001) and older (31.0% ≥ 70 years versus 25.8%; P = 0.0033) compared with rectal cancers patients. Patients with left-sided colon cancer had higher rates of liver metastases (80.9% versus 72.3%, P < 0.0001) but lower rates of lung metastases (34.2% versus 53.8%, P < 0.0001). KRAS mutations were slightly less frequent among left-sided tumours (34.8% versus 40.5%; P = 0.0103). Patients with left-sided tumours had approximately similar PFS (median 7.4 versus 6.9 months; hazard ratio [HR] 0.92, 95% confidence interval [CI] 0.87–1.03; P = 0.1998) and OS (median 17.4 versus 16.6 months; HR 0.99, 95% CI 0.91–1.07; P = 0.7597) compared with rectal cancer patients. Conclusion The site of tumour origin within the left side was not prognostic of outcomes. Moreover, neither bevacizumab nor cetuximab impacted, differently, the findings of the comparisons in outcomes between patients with left-sided colon tumours or rectal cancers. Highlights • We analysed data from 2879 patients in the ARCAD database according to their primary tumour location (left colon or rectum). • No outcome differences were observed between patients with left-sided colon and rectal tumours. • Progression-free and overall survival were comparable in all patients regardless of oxaliplatin- or irinotecan-based therapy. • Neither bevacizumab nor cetuximab treatment led to different outcomes in patients with left-sided colon vs. rectal tumours. • Despite clinical and molecular differences, our results suggest left-sided colon and rectal tumours can be treated the same. [ABSTRACT FROM AUTHOR]