ACCENT Database Research Articles

Clinicopathological and Molecular Characteristics of Early-Onset Stage III Colon Adenocarcinoma: An Analysis of the ACCENT Database.

Colon cancer (CC) incidence in young adults (age 20-49 years), termed early-onset CC (EO-CC), is increasing. Individual patient data on 35 713 subjects with stage III colon cancer from 25 randomized studies in the Adjuvant Colon Cancer ENdpoint database were pooled. The distributions of demographics, clinicopathological features, biomarker status, and outcome data were summarized by age group. Overall survival, disease-free survival, time to recurrence, and survival after recurrence were assessed by Kaplan-Meier curves and Cox models stratified by treatment arms within studies, adjusting for sex, race, body mass index, performance status, disease stage, grade, risk group, number of lymph nodes examined, disease sidedness, and molecular markers. All statistical tests were 2-sided. Using a 5% difference between age groups as the clinically meaningful cutoff, patients with stage III EO-CC had similar sex, race, performance status, risk group, tumor sidedness, and T stage compared with patients with late-onset CC (age 50 years and older). EO-CC patients were less likely to be overweight (30.2% vs 36.2%) and more commonly had 12 or more lymph nodes resected (69.5% vs 58.7%). EO-CC tumors were more frequently mismatch repair deficient (16.4% vs 11.5%) and less likely to have BRAFV600E (5.6% vs 14.0%), suggesting a higher rate of Lynch syndrome in EO-CC. Patients with EO-CC had statistically significantly better overall survival (hazard ratio [HR] = 0.81, 95% confidence interval [CI] = 0.74 to 0.89; P < .001), disease-free survival (HR = 0.91, 95% CI = 0.84 to 0.98; P = .01), and survival after recurrence (HR = 0.88, 95% CI = 0.80 to 0.97; P = .008) in the analysis without molecular markers; however, age at onset of CC lost its prognostic value when outcome was adjusted for molecular markers. Tumor biology was found to be a more important prognostic factor than age of onset among stage III colon cancer patients in the Adjuvant Colon Cancer ENdpoint database.

Benefit of Oxaliplatin in Stage III Colon Cancer According to IDEA Risk Groups: Findings from the ACCENT Database of 4934 Patients

BackgroundThe International Duration Evaluation of Adjuvant Chemotherapy (IDEA) pooled analysis compared 3 to 6 months of adjuvant chemotherapy for stage III colon cancer. Patients were classified into low risk and high risk, suggesting low-risk patients may be offered only 3 months of treatment. In this study, we aimed to assess the benefit of oxaliplatin in the adjuvant setting per IDEA risk groups, using data from 3 large adjuvant phase III studies, namely Multicenter International Study of Oxaliplatin/Fluorouracil/ Leucovorin in the Adjuvant Treatment of Colon Cancer (MOSAIC), C-07, and XELOXA. MethodsUsing the MOSAIC, C-07, and XELOXA previously published studies, we identified 2810 low-risk and 2124 high-risk patients with stage III colon cancer. We used Cox regression model to evaluate the magnitude of survival differences between IDEA risk groups, according to oxaliplatin use. Based on design similarity and equivalent follow-up data, MOSAIC and C-07 were pooled, whereas XELOXA was analyzed separately. Subgroup analyses were also performed for T4 and/or N2 patients. ResultsIndividuals with IDEA low and high risk derived overall survival benefit from the addition of oxaliplatin to adjuvant chemotherapy, with adjusted hazard ratios of 0.79 (0.66-0.95) and 0.84 (0.71-0.99), respectively. Among individuals with IDEA high risk, those with T4 disease did not gain overall survival benefit from addition of oxaliplatin with hazard ratio of 0.95 (0.71-1.27). Similar results were demonstrated using data from the XELOXA study. ConclusionIDEA risk classification per se does not predict benefit from addition of oxaliplatin to adjuvant chemotherapy in stage III colon cancer. T4 disease may predict lack of benefit from oxaliplatin addition.

Microsatellite Instability in Patients With Stage III Colon Cancer Receiving Fluoropyrimidine With or Without Oxaliplatin: An ACCENT Pooled Analysis of 12 Adjuvant Trials.

In patients with stage III colon cancer (CC) whose tumors demonstrate microsatellite instability (MSI), the efficacy of adjuvant fluoropyrimidine (FP) with or without oxaliplatin has not been clearly demonstrated and the prognostic value of MSI remains uncertain. Individual patient data from the ACCENT database were used to evaluate the effect of FP with or without oxaliplatin on disease-free survival (DFS) and overall survival (OS) among patients with MSI stage III CC and the prognostic value of MSI in patients treated with FP plus oxaliplatin, by stratified Cox models adjusted for demographic and clinicopathological factors. MSI status was available for 5,457 patients (609 MSI, 11.2%; 4848 microsatellite stable [MSS], 88.8%) from 12 randomized clinical trials (RCTs). Oxaliplatin significantly improved OS of MSI patients from the two RCTs testing FP with or without oxaliplatin (n = 185; adjusted hazard ratio [aHR] = 0.52, 95% CI, 0.28 to 0.93). Among the 4,250 patients treated with FP plus oxaliplatin (461 MSI and 3789 MSS), MSI was associated with better OS in the N1 group compared with MSS (aHR = 0.66; 95% CI, 0.46 to 0.95) but similar survival in the N2 population (aHR = 1.13; 95% CI, 0.86 to 1.48; P interaction = .029). The main independent prognosticators of MSI patients treated with FP plus oxaliplatin were T stage (aHR = 2.09; 95% CI, 1.29 to 3.38) and N stage (aHR = 3.57; 95% CI, 2.32 to 5.48). Similar results were observed for DFS in all analyses. Adding oxaliplatin to FP improves OS and DFS in patients with MSI stage III CC. Compared with MSS, MSI patients experienced better outcomes in the N1 group but similar survival in the N2 group.

Evaluation of the change of outcomes over a 10-year period in patients with stage III colon cancer: pooled analysis of 6501 patients treated with fluorouracil, leucovorin, and oxaliplatin in the ACCENT database

Since 2004, adjuvant 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX or FLOX) have been the standard of care for patients with resected colon cancer. Herein we examine the change of outcomes over a 10-year period in patients with stage III colon cancer who received this regimen. Individual patient data from the ACCENT database was used to compare the outcomes in older (1998-2003) and newer (2004-2009) treatment eras for patients with stage III colon cancer who received adjuvant FOLFOX or FLOX. The outcomes were compared between the two groups by the multivariate Cox proportional-hazards model adjusting for age, sex, performance score, T stage, N stage, tumor sidedness, and histological grade. A total of 6501 patients with stage III colon cancer who received adjuvant FOLFOX or FLOX in six randomized trials were included in the analysis. Patients enrolled in the new era group experienced statistically significant improvement in time to recurrence [3-year rate, 76.1% versus 73.0%; adjusted hazard ratio (HRadj)= 0.83 (95% CI, 0.74-0.92), P= 0.0008], disease-free survival (DFS) [3-year rate, 74.7% versus 72.3%; HRadj= 0.88 (0.79-0.98), P= 0.024], survival after recurrence (SAR) [median time, 27.0 versus 17.7 months; HRadj= 0.65 (0.57-0.74), P<0.0001], and overall survival (OS) [5-year rate, 80.9% versus 75.7%; HRadj= 0.78 (0.69-0.88), P < 0.0001]. The improved outcomes remained in patients diagnosed at 45 years of age or older, low-risk patients (T1-3 and N1), left colon, mismatch repair proficient (pMMR), BRAF, and KRAS wild-type tumors. Improved outcomes were observed in patients with stage III colon cancer enrolled in clinical trials who received adjuvant FOLFOX/FLOX therapy in 2004 or later compared with patients in the older era. Prolonged SAR calls for revalidation of 3-year DFS as the surrogate endpoint of OS in adjuvant clinical trials and reevaluation of optimal follow-up of OS to confirm the trial findings based on the DFS endpoints. NCT00079274; NCT00096278; NCT00004931; NCT00275210; NCT00265811; NCT00112918.

Re-evaluating disease-free survival (DFS) as an endpoint versus overall survival (OS) in adjuvant colon cancer (CC) trials with chemotherapy +/- biologics: An updated surrogacy analysis based on 18,886 patients (pts) from the Accent database.

3502 Background: DFS with 3 years median follow-up (3yDFS) was validated as a surrogate for OS with 5 years median follow-up (5yOS) in adjuvant chemotherapy CC trials prior. Recent data showed improved survival after recurrence and OS, over time, in pts who received adjuvant FOLFOX. Hence, re-evaluation of the association between DFS and OS, as well as the optimal follow-up of OS to aid its utility in future adjuvant trials is needed. Methods: Individual patient data from 8 randomized adjuvant studies conducted from 1998-2009 were included; 3 trials tested anti-VEGF or anti-EGFR agents. Trial-level surrogacy examining the correlation of treatment effect estimates (i.e. hazard ratios) of 3yDFS and 5y to 8yOS was evaluated using both linear regression (R2WLS) and Copula bivariate (R2Copula) models. For the R2, a value closer to 1 indicates a stronger correlation. Prespecified criteria for surrogacy required either R2WLS or R2Copula ≥ 0.80 and neither &lt; 0.7, with lower-bound 95% Confidence Interval (CI) &gt; 0.60. The rank correlation coefficient (ρ) quantified the individual-level surrogacy. Results: Total of 18,886 pts were analyzed, with median age 60, 54% male, 83% stage III, 59% &gt; 12 nodes examined. Median follow-up for survival ranged from 5 to 10 years across trials. Trial level correlation between 3yDFS and OS remained strong (R2WLS ≥0.74; R2Copula ≥ 0.89) and increased as the median follow-up of OS extended longer (see table). Analyses limited to stage III pts and/or trials tested biologics showed consistent results. Conclusions: 3yDFS remains a validated surrogate endpoint for 5yOS in adjuvant trials in CC pts per prespecified criteria. The correlation was strengthened with more than 6 years of follow-up for OS. [Table: see text]

Association of adverse events (AEs) with outcomes in early stage colon cancer (CC): An analysis of 10,695 CC patients from the ACCENT database.

3601Background: Initial dosing of adjuvant chemotherapy (ACT) is largely based on body surface area, but studies show that drug metabolism can vary significantly across patients. ACT-related toxici...

Association of sex and adverse events (AEs) of adjuvant chemotherapy (ACT) in early stage colon cancer (CC): A pooled analysis of 28,636 patients (pts) in the ACCENT database.

3603Background: Sex is one of several factors known to affect drug efficacy and toxicity. Preliminary data in different types of cancers suggest a higher toxicity of chemotherapy in women. Aim of t...

Outcomes over time (1998-2009) of stage II colon cancer patients (pts) receiving adjuvant FOLFOX: Pooled analysis of 1,122 pts in the ACCENT database.

728 Background: Adjuvant FOLFOX therapy for stage II patients remains controversial, and selection criteria are imprecise. We examined the trend of disease-free survival (DFS: time to recurrence or death, whichever occurs first); time to recurrence (TTR: time to recurrence, censored at death without recurrence); survival after recurrence (SAR); and overall survival (OS) of pts treated with FOLFOX over a ten-year period. Methods: Outcomes of pts with stage II colon cancer enrolled in 6 adjuvant trials receiving FOLFOX alone were analyzed. Pt enrollment period was dichotomized as old (1998 – 2003) vs. new era (2004 – 2009) based on the FDA approval date of bevacizumab. 3/5yr event-free rates were estimated using adjusted Kaplan-Meier methods. Outcomes were compared between the two eras by multivariate Cox model. To control for potential confounding effects, all analyses were adjusted for age, gender, performance score, T stage, number of lymph nodes (LNs) examined, tumor side, and histologic grade. Results: In total, 1,122 pts with stage II were identified; 71% and 29% were treated in the old and new era, respectively. Pts enrolled in the new era were significantly younger and more likely to have higher tumor-grade and right-sided tumors compared to old era. More pts in the new era (71%) had ≥12 LNs examined compared to the old era (53%). After adjusting for potential confounding effects, no difference in DFS, TTR, SAR or OS between old and new eras was found (Table). Although median SAR increased from 13.6 to 26 months over time, this was not statistically significant, likely due to lack of power. An increased TTR over time (HRadj. 0.41, padj.= 0.002) was observed in pts with ≥12 LNs examined (3-yr TTR: 92% in old era vs. 96% in new era), but not pts with &lt;12 LNs examined (pinteraction = 0.04). Conclusions: In stage II colon cancer pts who received adjuvant FOLFOX, no significant increase of DFS or OS was observed over time. However TTR was longer only in pts with ≥12 LNs examined. [Table: see text]

Evaluation of outcomes over time (1998-2009) of patients (pts) with stage III colon cancer receiving adjuvant FOLFOX: Analysis of 7,230 patients from MOSAIC, C07, C08, N0147, AVANT, and PETACC8 trials in the ACCENT Database.

724 Background: Adjuvant FOLFOX is the standard of care for pts with stage III colon cancer and a platform to test new agents. Improvements in supportive care and development of newer treatments for metastatic disease impact the overall outcome of pts treated with adjuvant therapy. We examined the trend of disease-free survival (DFS), survival after recurrence (SAR), and overall survival (OS) of pts treated with FOLFOX over a ten-year period. Methods: Outcomes of colon cancer pts enrolled in 6 adjuvant trials receiving FOLFOX alone were analyzed. Pt enrollment period was dichotomized as old (1998 – 2003) vs. new era (2004 – 2009) based on the FDA approval date of bevacizumab. 3/5yr event-free rates were estimated by adjusted Kaplan-Meier methods. Outcomes were compared between the two eras by Cox model. To control for potential confounding effects, all analyses were adjusted for age, gender, performance score, T/N stage, tumor sidedness and histologic grade. Results: In total, 7,230 pts (stage II [n = 1122]; stage III [n = 6,108]) were identified; 32% and 68% were treated in the old and new era, respectively. Stage III pts enrolled in the new era were significantly younger, more likely to have T4/N2 disease, higher tumor grade, and left-sided tumors. After adjusting for pt characteristics, no difference in DFS was seen over time. However prolonged SAR and OS were observed in pts treated in the new era (Table). 5yr OS increased from 76% to 80% over time. Median SAR improved from 14.8 to 26.4 months. Conclusions: Stage III colon cancer pts who received adjuvant FOLFOX experienced significant improvements in SAR and OS—but not DFS—over time. In view of the improvements in OS and nearly doubled SAR, the optimal duration of OS follow-up to evaluate the benefits of adjuvant therapy (currently 5 years) should be reassessed, and ACCENT investigators are planning to conduct these additional analyses using their large pooled-trial database. [Table: see text]

Validity of Adjuvant! Online in older patients with stage III colon cancer based on 2967 patients from the ACCENT database.

Adjuvant! Online is a tool used for clinical decision making in patients with early stage colon cancer. As details of the tool's construction are not published, the ability of Adjuvant! Online to accurately predict outcomes for older patients (age 70+) with node positive colon cancer receiving adjuvant chemotherapy is unclear. Individual data from older patients with stage III colon cancer who enrolled into multiple trials within the ACCENT database were entered into the Adjuvant! Online program to obtain predicted probabilities of 5-year overall survival (OS) and recurrence-free survival (RFS). Median predictions were compared with known rates. As co-morbidities were not known for ACCENT patients, but required for calculator entry, patients were assumed to have either "minor" or "average for age" co-morbidities. 2967 older patients from 10 randomized studies were included. When "minor" co-morbidities were assumed, the median predicted 5-year OS rate of 64% nearly matched the actual rate of 65%; when "average for age" co-morbidities were assumed, the median prediction dropped to 58%, outside the CI for the actual rate. On the other hand, assuming "minor" co-morbidities gave a median 5-year RFS prediction of 62%, outside the 95% CI for the actual rate of 58%, while assuming "average for age" co-morbidities yielded a better median prediction of 57%. Adjuvant! Online is reasonably accurate overall for predicting outcomes in older trial patients with stage III colon cancer, though accuracy may differ between 5-year RFS and 5-year OS predictions when a fixed degree of co-morbidities is assumed.

Validity of Adjuvant! Online in elderly patients with stage III colon cancer based on 2,794 patients from the ACCENT database.

3620Background: Adjuvant! Online is a tool used for clinical decision making in patients (pts) with early stage colon cancer. As the tool’s construction and validation has never been published, it remains whether Adjuvant! Online can accurately predict outcomes for elderly pts (age 70+) with node positive colon cancer who received adjuvant chemotherapy. Methods: Individual data from elderly pts with stage III colon cancer who enrolled into ACCENT trials were entered into the Adjuvant! Online program, and predicted probabilities of 5-year overall survival (OS) and recurrence-free survival (RFS) were obtained. Median predictions were then compared with known rates and their 95% CIs, overall and within pt subgroups. As co-morbidities were not known for ACCENT pts but required for calculator entry, pts were assumed to have either “minor” or “average for age” co-morbidities in two separate analyses. Results: A total of 2,794 elderly pts from 14 randomized studies were included. When “minor” comorbidities were ...

Determinants of early mortality in 37,568 colon cancer patients participating in 25 clinical trials of the ACCENT database.

6580 Background: Clinical trials are the gold standard for evaluating novel therapeutics. Accrual of patients (pts) at substantial risk of significant treatment toxicity or early mortality compromi...

Time-dependent patterns of recurrence and death in resected colon cancer (CC): Pooled analysis of 12,223 patients from modern trials in the ACCENT database containing oxaliplatin.

3593 Background: A 2009 analysis of 20,898 CC patients from 18 randomized studies of adjuvant therapy (AT) in the ACCENT database showed that treatment with AT (versus surgery alone) lowers the ris...

Prognostic impact of deficient mismatch repair (dMMR) in 7,803 stage II/III colon cancer (CC) patients (pts): A pooled individual pt data analysis of 17 adjuvant trials in the ACCENT database.

3507 Background: MMR status has been established as an important prognostic factor in CC pts. We determined the association of dMMR status with clinical/pathological features and prognosis using th...

Comparison of Outcomes After Fluorouracil-Based Adjuvant Therapy for Stages II and III Colon Cancer Between 1978 to 1995 and 1996 to 2007: Evidence of Stage Migration From the ACCENT Database

With improved patient care, better diagnosis, and more treatment options after tumor recurrence, outcomes after fluorouracil (FU) -based treatment are expected to have improved over time in early-stage colon cancer. Data from 18,449 patients enrolled onto 21 phase III trials conducted from 1978 to 2002 were evaluated for potential differences in time to recurrence (TTR), time from recurrence to death (TRD), and overall survival (OS) with regard to FU-based adjuvant regimens. Trials were predefined as old versus newer era using initial accrual before or after 1995. Outcomes were compared between patients enrolled onto old- or newer-era trials, stratified by stage. Within the first 3 years, recurrence rates were lower in newer- versus old-era trials for patients with stage II disease, with no differences among those with stage III disease. Both TRD and OS were significantly longer in newer-era trials overall and within each stage. The lymph node (LN) ratio (ie, number of positive nodes divided by total nodes harvested) in those with stage III disease declined over time. TTR improved slightly, with larger number of LNs examined in both stages. Improved TRD in newer trials supports the premise that more aggressive intervention (oxaliplatin- and irinotecan-based chemotherapy and/or surgery for recurrent disease) improves OS for patients previously treated in the adjuvant setting. Lower recurrence rates with identical treatments in those with stage II disease enrolled onto newer-era trials reflect stage migration over time, calling into question historical data related to the benefit of FU-based adjuvant therapy in such patients.

The Predictive and Prognostic Value of Sex in Early-Stage Colon Cancer: A Pooled Analysis of 33,345 Patients from the ACCENT Database

PurposeTo compare long-term outcomes between men and women in a large cohort of clinical trial participants with early-stage colon cancer, specifically by examining whether the prognostic effect of sex varies based on age, stage of disease, and type of adjuvant therapy received. MethodsA pooled analysis of individual patient data from 33,345 patients with colon cancer enrolled in 24 phase III studies of various adjuvant systemic therapies was conducted. Chemotherapy consisted of (1) fluorouracil (5-FU), (2) 5-FU variations, (3) 5-FU plus oxaliplatin, (4) 5-FU plus irinotecan, or (5) oral fluoropyrimidine-based regimens. The primary endpoint was disease-free survival; secondary endpoints included overall survival and time to recurrence. Stratified Cox models were used to assess the effect of sex on outcomes. Multivariate models were used to assess adjusted effects and to explore the interaction among sex and other factors. ResultsA total of 18,244 (55%) men and 15,101 (45%) women were included. In the entire cohort, the median age was 61 years; 91% (24,868) were white; 31% (10,347) and 69% (22,964) had stage I/II and III disease, respectively. Overall, men had inferior prognoses when compared with women for time to recurrence (hazard ratio [HR] 1.05 [95% CI, 1.01-1.09]) and other endpoints after adjusting for age, stage, and treatment. Sex was not a predictive factor of treatment efficacy (P for interaction between sex and treatment when adjusting for age and stage were .40, .67, and .77 for disease-free survival, overall survival, and time to recurrence, respectively). In exploratory analyses, worse outcomes in men were more prominent in the older patients when adjusting for stage and treatment (HR 1.08 in age ≤ 65 years vs. HR 1.18 in age > 65 years; interaction P = .016 for disease-free survival). The stage of disease and type of adjuvant regimen did not modify the prognostic value of sex. ConclusionsSex is a modest independent prognostic marker for patients with early-stage colon cancer, particularly in older patients.

Accent-based nomograms (NGs) to predict time to recurrence (TTR) and overall survival (OS) in stage III colon cancer (CC).

3618 Background: Current prognostic tools and staging systems in CC use relatively few patient (pt) characteristics; including additional covariates may improve prediction. Using the large ACCENT database, we constructed clinically based NGs for OS and TTR in stage III CC that better separate pts into risk groups compared to AJCC v7 staging. Methods: 15,936 stage III pts accrued to phase III clinical trials since 1989 were used to construct Cox models for TTR and OS. Variables included age, sex, race, BMI, performance status, tumor grade, tumor stage, ratio of positive lymph nodes to nodes examined, number/location of primary tumors (any multiple versus single left, right, or transverse), and treatment (5FU variations vs. 5FU with oxaliplatin or irinotecan). Missing data (&lt;18%) were imputed, continuous variables modeled with splines, and clinically relevant pairwise interactions included if p &lt; 0.001. Final models were internally validated via bootstrapping for corrected calibration and C-indices for survival data. NG-defined risk tertiles were compared to AJCC v7 stage III for observed 3-year (yr) TTR and 5-yr OS for a subset of 7400 pts with complete data. Results: All variables were statistically and clinically significant for OS; age and race did not predict TTR. No meaningful interactions existed. NGs for OS and TTR were well calibrated and associated with C-indices of 0.66 and 0.65, respectively, vs. 0.58 and 0.59 for AJCC. NG risk tertiles were better separated than AJCC groups, (3-yr TTR, 5-yr OS below), with fewer mid-risk NG pts. Removing treatment from NGs did not affect performance (C=0.66 for OS and 0.65 for TTR). Conclusions: The proposed ACCENT NGs are internally valid and have the potential to aid prognostication, decision-making, and patient/physician communication in pts with stage III CC. [Table: see text]

Innovative estimation of survival using log-normal survival modelling on ACCENT database

Background:The ACCENT database, with individual patient data for 20 898 patients from 18 colon cancer clinical trials, was used to support Food and Drug Administration (FDA) approval of 3-year disease-free survival as a surrogate for 5-year overall survival. We hypothesised substantive differences in survival estimation with log-normal modelling rather than standard Kaplan–Meier or Cox approaches.Methods:Time to relapse, disease-free survival, and overall survival were estimated using Kaplan–Meier, Cox, and log-normal approaches for male subjects aged 60–65 years, with stage III colon cancer, treated with 5-fluorouracil-based chemotherapy regimens (with 5FU), or with surgery alone (without 5FU).Results:Absolute differences between Cox and log-normal estimates with (without) 5FU varied by end point. The log-normal model had 5.8 (6.3)% higher estimated 3-year time to relapse than the Cox model; 4.8 (5.1)% higher 3-year disease-free survival; and 3.2 (2.2)% higher 5-year overall survival. Model checking indicated greater data support for the log-normal than the Cox model, with Cox and Kaplan–Meier estimates being more similar. All three model types indicate consistent evidence of treatment benefit on both 3-year disease-free survival and 5-year overall survival; patients allocated to 5FU had 5.0–6.7% higher 3-year disease-free survival and 5.3–6.8% higher 5-year overall survival.Conclusion:Substantive absolute differences between estimates of 3-year disease-free survival and 5-year overall survival with log-normal and Cox models were large enough to be clinically relevant, and warrant further consideration.

Comparison of innovative estimation of efficacy to standard using the ACCENT database.

3616 Background: The ACCENT database contains individual patient data from over 32,000 patients enrolled onto 18 international clinical trials. Based on recent breast cancer literature, we hypothes...

Lymph node (LN) ratio (LNR) risk classification (RC) in stage III colon cancer (CC): A pooled analysis of 16,425 patients from the ACCENT database.

3556 Background: The degree of LN involvement is one of the most important prognostic factors in CC. Current staging does not consider the number of total LN examined (TLN) and its predictive ability of nodal associated disease RC. Our aim was to develop a RC model based on LNR with internal and external validation. Methods: Individual patient (pt) data from 18 randomized clinical trials were used. LNR is defined as number of positive LNs divided by number of TLN. The primary endpoint was disease-free survival (DFS). The development dataset consisted of pts receiving 5FU based chemotherapy only. This dataset was randomly split into a training set (6848 pt) and an internal validation set (4952 pt). Pts receiving surgery alone (951 pt) and 5FU plus other agents (oxaliplatin, irinotecan, or oral-based) (3674 pt) comprised two external validation populations. Optimal cutoffs were selected based on Cox model goodness of fit. Validation was based on two key aspects of a predication model - discrimination (c sta...