Citations

4044 Background: To aid in decisions regarding adjuvant therapy (AT) for resected high-risk CC, two prog models are in common use: the Mayo Clinic NUM calculator developed from a pooled data analysis of 7 randomized 5FU-based AT trials, and ADJ! developed using SEER data. This study examines the accuracy of NUM and ADJ! utilizing a cohort of patients (pts) referred to the BC Cancer Agency (BCCA). Methods: Demographic, disease and treatment data for pts with stage II/III CC referred to the BCCA from 1995–1996 + 1999–2003 were collected. Observed (obs) 5-year relapse free survival (RFS) and overall survival (OS) were compared to predicted estimates (pred) using NUM and ADJ!, both overall and for all prog subgroups with ≥ 10pts, as stratified by T stage, N stage, tumor grade and age. Data are presented in a descriptive manner and using confidence intervals. Results: Median follow-up was 5.6 yrs for 2,033 pts - 53% male, median age 68y, 40% N0. The mean percentages of 5 year pred outcomes for each of the two models and the actual Kaplan Meier mean survivals are presented in the table . The percentage correct predictions of 5 y status is also presented, with correctness deemed accurate if the pt was alive and predicted to be alive by ≥ 50% as determined by each model or dead while the respective tool predicted < 50% possibility of being alive. For surgery alone pts, ADJ!pred were more often closer to what was observed, as compared to NUMpred, in the prog subgroups (for RFS 56%, OS 88%). For surgery + 5-FU pts, within these subgroups, NUMpred were more often closer to what was observed, as compared to ADJ!pred, for RFS (62%) and for OS (55%). Conclusions: In this independent population-based validation, NUM and ADJ! have acceptable and similar reliability with modest over-estimations of 5y RFS and OS. Both models thus appear to be useful adjuvant decision-aids. [Table: see text] No significant financial relationships to disclose.

4013 Background: Intensive postoperative surveillance is associated with improved survival and recommended for patients with late stage (stage IIB & III) colon cancer. We hypothesized that stage I & IIA colon cancer patients would experience similar benefits. Methods: Secondary analysis of data from the Clinical Outcomes of Surgical Therapy trial was performed by analyzing results according to TNM stage; early (stage I & IIA; 537 patients) and late (stage IIB & III; 254 patients) stage disease. Five-year recurrence rates were higher in patients with late (35.7%) versus early stage disease (9.5%). Early and late stage salvage rates, recurrence patterns and methods of first detection were compared by χ2 test. Results: Salvage rates for early and late stage disease patients with recurrence were the same (35.9% versus 37%, p=0.9 respectively). Median survival following second surgery after recurrence was 35.8 months late stage and 51.2 months for early stage patients respectively. Sites of first recurrence did not significantly differ between late and early stage disease: liver (37.4% vs. 27.2%); lung (29.7% vs.23.6%); intraabdominal (24.2% vs.10.9%); and locoregional (12.1% vs.10.9%). Methods of first detection of recurrence were also not significantly different: CEA (37.4% vs. 29.1%); CT scan (26.4% vs. 23.6%); chest X-ray (12.1% vs. 7.3%); and colonoscopy (8.8% vs. 12.7%), for late versus early stage disease, respectively. Conclusions: Patients with early stage colon cancer have similar sites of recurrence, and receive similar benefit from post-recurrence therapy as later stage patients; implementation of existing surveillance guidelines for early stage patients is appropriate. No significant financial relationships to disclose.

4011 Background: The ACCENT group previously validated DFS with 3 years (yr) median follow-up (f-up) based on 20,898 pts from trials testing 5-FU based regimens (rx) (3yr DFS) as an endpoint to predict overall survival with 5 yr median f-up (5yr OS) (Sargent, JCO 2005). ACCENT further proposed (1) 2yr DFS predicts 5yr OS, (2) a stronger relationship between DFS and OS in stage III pts (Sargent JCO 2007) and (3) 6 or 7 yrs are necessary to demonstrate DFS and OS association in future trials due to extended survival following recurrence (de Gramont ASCO 2008). The relationship between endpoints in more recent trials with oral fluoropyrimidines, oxaliplatin, and irinotecan is unknown. Methods: Concordance between 2 and 3yr DFS, and 5 and 6yr OS was examined in 6 randomized phase III trials from 1997–2002. Individual data for 12,676 pts was analyzed; 2 trials tested oxaliplatin, 2 irinotecan, and 2 oral rx vs 5-FU/LV control. Association between DFS and OS hazard ratios (HRs) via weighted least squares (WLS), and concordance between predicted and actual within-trial HRs, were calculated overall and for stage III pts. Results: Overall association between 3 yr DFS and 5 yr OS HRs was reduced compared to the prior ACCENT analysis (Table). In stage III pts, the association between DFS and OS HRs remained strong. Observed 5 and 6yr OS HRs were predicted accurately by 2yr DFS overall and in stage III pts (within 95% prediction limits in all trials). In all pts, DFS HRs were more highly associated with 6 vs 5yr OS HRs. Conclusions: In recent trials in stage III pts, DFS HRs based on 2yr median f-up are highly predictive of 5 and 6yr OS HRs. In all pts the association between DFS and OS HRs is stronger for 6yr OS, but 7yr follow-up may be required. These data support 3yr DFS as a primary endpoint for modern stage III trials, and indicate that 2yr DFS would also be an appropriate primary endpoint. [Table: see text] [Table: see text]

e15031 Background: Two web based prognostic calculators, Adjuvant! and Numeracy (JCO 22:1797–1806, 2004) are widely used to provide individual patient outcome predictions to aid decisions regarding adjuvant therapy for colon cancer. The comparability of these tools has not been studied yet. The aim of this project was to assess whether the Numeracy and Adjuvant! Colon cancer prognostic tools produced similar results for patients with resected stage II and III colon cancer based on a set of hypothetical patients. Methods: All possible hypothetical scenarios were formulated for the Numeracy calculator based on all potential combinations of age, lymph nodes status, tumor stage, and grade of tumor. These were applied to three post- surgical therapy choices: observation, 5-FU (5-fluorouracil), or FOLFOX (5-FU, leucovorin and oxaliplatin). Predictions for these hypothetical scenarios (N= 192 for males and 192 for females) were also entered into the Adjuvant! Program. Predicted relapse free survival (RFS) and overall survival (OS) were obtained using both calculators. Wilcoxon signed rank tests were used to compare the numerical predictions between the calculators for each outcome. Results: In the majority of the 384 hypothetical patient scenarios, predictions for RFS and OS from Adjuvant! were statistically significantly higher than from Numeracy (p value < 0.05), except for age≥70 for FOLFOX, and the number of positive nodes of 0 and 1–4 using FOLFOX, among males. The net estimate of benefit for RFS and OS for 5-FU over surgery, obtained from Adjuvant! and Numeracy, were similar (for both males and females), but the benefit in RFS and OS for FOLFOX over 5-FU obtained from Adjuvant! was significantly lower than the estimate obtained from Numeracy (p value < 0.05). Conclusions: Based on a hypothetical set of patients with resected stage II and III colon cancer, the estimated benefit in RFS and OS of FOLFOX over 5-FU based chemotherapy is lower in Adjuvant! than in the Numeracy tool (but benefit for 5-FU over surgery alone is similar). Further studies are needed to clarify the discrepancy and to assess which of these tools most accurately reflects actual patient outcome. No significant financial relationships to disclose.

4010 Background: Prior studies suggested that older and younger pts with colon cancer receive similar benefit from IV fluoropyrimidine (FU) adjuvant (adj) therapy (rx). Combination and/or oral FU rx are increasingly given as adj rx. We sought to determine the impact of pts age <70 v ≥70 yrs on colon cancer recurrence and mortality from adj rx with these newer options. Methods: We used data from 10,499 pts <70 yrs and 2,170 pts ≥70 yrs in 6 phase III adj rx trials comparing IV FU to combinations with irinotecan, oxaliplatin or oral FU (capecitabine and UFT/LV) in stage II/III colon cancer from the ACCENT database. Endpoints were overall survival (OS; time to death), disease-free survival (DFS; time to recurrence or death), and time to recurrence (TTR; censoring at last follow-up). Cox models were stratified by age and adjusted for gender and stage; interaction testing was used to explore the differential benefit by age. Results: Approximately 75% of pts had stage III disease (74% age<70, 77% age≥70). OS, DFS, and TTR were statistically significantly improved for those in the experimental v control arms among pts <70 but not those >70 ( table ); the interaction between age and rx was statistically significant for all endpoints (p=0.01 for OS, DFS, and TTR). These results were consistent whether experimental rx was oxaliplatin-based, irinotecan-based or oral FU. Deaths in first 6 month of adj rx were not statistically significantly different between experimental and control arm. Conclusions: Our results show conclusively that pts >70 do not receive the same benefit from combination and/or oral FU as those <70. Any benefit, if present, compared to IV FU/LV would not be clinically meaningful. Outcomes of experimental (combination or oral FU) vs control (IV 5-FU) by treatment and age [Table: see text] [Table: see text]

3637 Background: In the CORRECT phase III trial, the multikinase inhibitor REG demonstrated significant improvement in overall survival and progression-free survival vs placebo (P) in patients with mCRC whose disease had progressed on other standard therapies. The most frequent grade 3 AEs were hand–foot skin reaction (HFSR), fatigue, diarrhea, hypertension, and rash. We examined when these AEs first occurred and what impact they had on REG dosing. Methods: Adults with mCRC progressing after all standard therapies were randomized to receive REG 160 mg (n=505) or P (n=255) orally once daily for the first 3 weeks of each 4-week cycle. AEs were managed with dose modifications (reduction and interruption) according to the protocol. Results: The safety population comprised 753 pts (REG n=500, P n=253). The mean ± SD treatment duration was 12.1 ± 9.7 weeks for REG and 7.8 ± 5.2 weeks for P. Treatment-emergent AEs occurred in 99.6% of REG pts and 96.8% of P pts. AEs occurring in ≥10% more REG than P pts were fatigue, HFSR, anorexia, diarrhea, weight loss, voice changes, hypertension, rash/desquamation, oral mucositis, fever, hyperbilirubinemia, and low platelet count. The incidence of grade ≥3 HFSR, fatigue, hypertension, and rash/desquamation typically peaked in cycle 1 and tapered to a relatively stable lower incidence over later cycles, while the incidence of diarrhea remained relatively constant throughout the study; median time to first occurrence and worst grade of these AEs is shown in the table. AEs led to dose modifications in 66.6% of REG pts and 22.5% of P pts. Conclusions: The most common AEs in the REG group typically occurred early during treatment. Close early monitoring of AEs and proper management by dose modification is recommended. Clinical trial information: NCT01103323. [Table: see text]

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 (<18%) were imputed, continuous variables modeled with splines, and clinically relevant pairwise interactions included if p < 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]

3533 Background: PFS has previously been established as a surrogate for OS based on IPD from first-line mCRC trials conducted before 1999. As mCRC treatment (trt) has advanced in the last decade and OS has increased from 1 to 2 years, this surrogacy required re-examination. Methods: IPD from 16,762 pts, median age 62, 62% male, 53% ECOG PS 0 were available from 22 1st line mCRC studies conducted from 1997-2006; 12 tested targeted (anti-angiogenic and/or anti-EGFR) regimens. The relationship between PFS (first event of progression or death) and OS was evaluated at patient-, trt-arm-, and trial-levels using correlation (corr.) coefficients and R2 (closer to 1 the better) from weighted least square (WLS) regression of arm-specific survival rates and trial-specific hazard ratios (HRs), estimated using Cox and Copula bivariate models. The concordance of significance (CoS) of the treatment effects (TEs) on both endpoints was calculated. Results: 44% pts received a targeted regimen. Median PFS was 8 and OS was18 months. The corr. between PFS and OS was modest at all three levels with low CoS in TE comparisons (see Table). Analyses limited to trials testing targeted trts, non-strategy trials, or superiority trials did not improve surrogacy. Conclusions: In modern mCRC trials, where survival post-first progression exceeds time to first progression, PFS TEs do not reliably predict TEs on OS. Nonetheless, until alternative endpoints of clinical benefit can be validated, PFS remains a relevant primary endpoint for 1st line mCRC trials, as our data demonstrate that the ability for any agent to produce an OS benefit from a single line of therapy is challenging. [Table: see text]

3514 Background: In the CORRECT phase III trial, the multikinase inhibitor regorafenib (REG) demonstrated significant improvement in overall survival (OS) and progression-free survival (PFS) vs placebo (Pla) in patients with metastatic colorectal cancer (mCRC) whose disease had progressed on other standard therapies. An exploratory biomarker subanalysis was conducted to identify protein biomarkers with potential predictive or prognostic value. Methods: Fifteen proteins of interest, many of which are involved in angiogenesis, were quantified by multiplex immunoassay or ELISA in baseline plasma samples collected at study entry from 80% (611/760) of patients. Potential predictive and prognostic effects were evaluated. Results: The biomarker subpopulation was representative of the overall study population in terms of OS and PFS. Using OS as the clinical endpoint, Tie-1 was the only protein whose level demonstrated significant correlation with efficacy (low protein group: REG/Pla, HR 0.87; high protein group, HR 0.56; interaction, p=0.035). Using PFS as the clinical endpoint, von Willebrand factor (VWF) was the only protein whose level demonstrated significant correlation with efficacy (low protein group: REG/Pla, HR 0.39; high protein group, HR 0.60; interaction, p=0.02). Following correction for multiple testing, neither Tie-1 nor VWF data retained statistical significance. Baseline levels of IL-8 and placental growth factor (PlGF) were found to have prognostic value for OS (IL-8: high/low protein levels, HR 3.48, p<0.001; PIGF: HR 1.81, p=0.002). IL-8 was also prognostic for PFS (high/low protein levels: HR 1.63, p<0.001). Conclusions: None of the plasma proteins examined showed significant predictive value for REG efficacy after multiple testing correction. The association between baseline levels of Tie-1/VWF and REG efficacy may be a hypothesis to be tested in further trials. Clinical trial information: NCT01103323.

3617 Background: In metastatic colorectal cancer (CRC), previous studies suggested potential relationships between certain drug metabolizing (DM) genes (DPYD, ERCC2, GSTP1 and TYMS) and QOL prior to receipt of chemotherapy (Sloan, Plenary Session ASCO 2004). The current study is the first to examine relationships between similar DM genes and QOL in stage III CC pts. Methods: 1,583 CC pts on a randomized adjuvant stage III, phase III trial received FOLFOX, FOLFIRI, or either +/- Cetuximab. Genomic DNA and baseline QOL data via linear analogue self assessment (LASA) scales with 4 QOL variables were obtained. 53 DM SNPs were selected for known functional effect within potential regulatory sites. Two-sample t-tests assessed differences in QOL between pts with variants and wild-type status. Differences of at least 10 points on a 0-100 point QOL score were considered clinically significant. Results: 14 relationships between DM genes and QOL were detected at the nominal p < 0.05 level; six of these were related to DPYD, ERCC2, GSTP1 and TYMS. Relationships were also observed at the 0.05 level with polymorphisms of genes DPYS, ERCC1, MGMT, MTHFR, OPRT and UGT1A1 based on unadjusted and adjusted association tests. GSTP1 I105V and OPRT 5’UTR 28 A>G markers differed on fatigue scores (p=0.04, 0.005, respectively). Variants on MTHFR R594Q were associated with higher mental acuity scores (p=0.02). These relationships remained after adjusting for age, gender, race, T stage, PS, disease site, lymph nodes involved, and grade. The robustness of the observed associations varied with the multiple comparison adjustment method. Conclusions: Similar to the earlier study of stage IV CRC, we observed a possible relationship in pts with Stage III CC with regard to DM genes and QOL, although these relationships were more modest than observed in Stage IV pts. These DM genes may be in linkage disequilibrium with other genetic variants that more directly affect behavior and QOL. Further genome wide association studies are needed to clarify these relationships.