Citations

108 Background: Primary tumor sidedness has emerged as a prognostic and predictive biomarker for patients (pts) with metastatic colorectal cancer (mCRC). Tumor bulk has also been postulated to predict response to anti-EGFR therapy. We sought to evaluate the role of tumor bulk as a predictive biomarker to anti-EGFR therapy in pts with left- (LS) and right-sided (RS) mCRC. Methods: Data from 476 pts with mCRC enrolled across 2 first-line trials of anti-EGFR plus chemotherapy versus chemotherapy were pooled. Pts were included if there was available information on tumor sidedness and tumor bulk. All were KRAS wild-type and BRAF wild-type or unknown BRAF status. The right colon was defined as the cecum through the transverse colon, and the left colon as the splenic flexure through the rectum. Tumor bulk was the mean tumor size of target lesions at baseline, bulky defined as > 3.5 cm. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier and Cox models adjusting for performance status (PS), platelet count, primary tumor (PT) resection, number of metastatic sites, and stratified by study. Results: Pts with bulky tumors (211, 44%) had higher PS, white blood cell and platelet counts, higher CEA, fewer sites of metastatic disease, more liver than lung metastases, and fewer had PT resection. OS and PFS medians in months (mos) are presented in the table with 95% confidence intervals (95%CIs). Bulky tumors had inferior median OS compared with non-bulky (mOS, 17.9 vs. 21.3 mos, HRadj 1.33, 95% CI 1.05-1.69, P = 0.016) although median PFS was similar (mPFS, 8.6 vs. 8.7 mos, HRadj 1.15, 95% CI 0.92-1.42, P = 0.21). Conclusions: Tumor bulk is an independent prognostic factor for OS in KRAS wild-type and BRAF wild-type or unknown BRAF status pts. Pts with non-bulky RS tumors have survival outcomes similar to pts with bulky LS tumors. Although the mPFS for pts with RS tumors treated with anti-EGFR therapy was the lowest across subgroups, this finding was not statistically significant. Further research is warranted into whether pts with bulky RS tumors benefit from anti-EGFR therapy. Clinical trial information: NCT00182715, NCT00640081. [Table: see text]

PURPOSE: As oxaliplatin results in cumulative neurotoxicity, reducing treatment duration without loss of efficacy would benefit patients and healthcare providers. PATIENTS AND METHODS: Four of the six studies in the International Duration Evaluation of Adjuvant Chemotherapy (IDEA) collaboration included patients with high-risk stage II colon and rectal cancers. Patients were treated (clinician and/or patient choice) with either fluorouracil, leucovorin, and oxaliplatin (FOLFOX) or capecitabine and oxaliplatin (CAPOX) and randomly assigned to receive 3- or 6-month treatment. The primary end point is disease-free survival (DFS), and noninferiority of 3-month treatment was defined as a hazard ratio (HR) of < 1.2- v 6-month arm. To detect this with 80% power at a one-sided type one error rate of 0.10, a total of 542 DFS events were required. RESULTS: 3,273 eligible patients were randomly assigned to either 3- or 6-month treatment with 62% receiving CAPOX and 38% FOLFOX. There were 553 DFS events. Five-year DFS was 80.7% and 83.9% for 3-month and 6-month treatment, respectively (HR, 1.17; 80% CI, 1.05 to 1.31; P [for noninferiority] .39). This crossed the noninferiority limit of 1.2. As in the IDEA stage III analysis, the duration effect appeared dependent on the chemotherapy regimen although a test of interaction was negative. HR for CAPOX was 1.02 (80% CI, 0.88 to 1.17), and HR for FOLFOX was 1.41 (80% CI, 1.18 to 1.68). CONCLUSION: Although noninferiority has not been demonstrated in the overall population, the convenience, reduced toxicity, and cost of 3-month adjuvant CAPOX suggest it as a potential option for high-risk stage II colon cancer if oxaliplatin-based chemotherapy is suitable. The relative contribution of the factors used to define high-risk stage II disease needs better understanding.

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

9599 Background: We have previously identified overall a single-item measure for baseline quality of life (QOL) as a strong prognostic factor for survival (Tan, ASCO 2008), and that fatigue was an important component of patient QOL (Sloan, 2007). To explore whether patient-reported fatigue was supplemental or redundant to the prognostic information of overall QOL, we performed a patient-level pooled analysis of 43 NCCTG and MCCC oncology clinical trials of the effect of baseline fatigue on OS. Methods: 3,915 patients participating in 43 trials provided data at baseline for fatigue on a single-item 0–100 point scale. OS was tested for association with clinically deficient fatigue (CDF, score 0–50, n=1,497) vs not clinically deficient fatigue (nCDF, score 51–100, n=2,418). Cox proportional hazards models adjusted for the effects of overall QOL, performance score, race, disease site, age and gender. Results: Baseline fatigue was a strong predictor of OS for the entire patient cohort (CDF vs. nCDF: 31.5 mos vs >83.9 mos, p<0.0001). The effect sizes were consistent across different disease sites (GI, esophageal, head and neck, prostate, lung, breast and others). After controlling for covariates, including performance status and overall QOL, baseline fatigue remained a strong prognostic factor in multivariate models (CDF vs. nCDF: HR=1.23, p=0.02). Conclusions: Fatigue is a strong prognostic factor for OS independent of overall QOL and PS in a wide variety of oncology patient populations. Single-item measures of overall QOL and fatigue can help to identify vulnerable subpopulations among cancer patients. No significant financial relationships to disclose.

9563 Background: Fatigue is a prevalent and debilitating symptom reported by cancer patients (pts) which compromises a pt's quality of life (QOL). This study examined the relationship between PR fatigue and QOL as well as cancer-related symptoms (CRS) in 43 North Central Cancer Treatment Group and Mayo Clinic Cancer Center clinical trials. Methods: 3,915 pts from 43 oncology clinical trials provided baseline fatigue data on a single-item 0–100 point scale. Pts' QOL assessment included a single-item overall QOL and associated QOL domains measured by numerical analogues, the Profile of Mood States (POMS), and PR symptom assessment measures. Associations between fatigue and QOL domains were assessed by Spearman correlation coefficients. Wilcoxon rank sum test compared QOL scores between pts with clinically deficient fatigue(CDF, score ≤50) vs. no clinically deficient fatigue (nCDF, score>50). Changes from baseline in fatigue and QOL were compared by Wilcoxon rank sum test with a 20-point change defined as clinically meaningful. Results: 38% of pts reported CDF at baseline and 45% of pts reported CDF at last assessment. Fatigue was only moderately correlated at best with overall QOL, pain, POMS, social and physical function (Spearman rho's of .27,.40, .56, .38 and .38 respectively). Pts with CDF averaged over 10 points lower overall QOL, pain, POMS, social, and physical function (see table below, all p<.0001) as well as worsening CRS including sleepiness, nausea, headache, abnormal sweating, trouble sleeping, dry mouth, and sexual dysfunction (all p<.001). Pts with 20+ points worsening in fatigue declined in overall QOL, physical function, pain and POMS (all p<.0001). Conclusions: Patients with CDF suffer greater deficits in QOL and CRS. Patients report fatigue as distinctly different from overall QOL, pain, physical, social, mood status and CRS. Fatigue appears with a broad spectrum of CRS clusters. Routine measurement and management of fatigue could impact QOL and treatment-related symptoms. [Table: see text] No significant financial relationships to disclose.

6512 Background: The use of randomized phase II designs with an experimental arm and a standard-treatment control arm (R2PII) instead of a conventional single-arm design is clearly increasing in oncology. In practice, sample size, related cost issues, the belief that historical controls are adequate, and the use of a standard-treatment control arm in a phase II setting are frequently raised objections to R2PII trials. As the expense and complexity of definitive phase III trials increase, the ability of phase II trials to provide reliable and accurate results is critical. Methods: We investigated the ability of single arm vs R2PII trials to provide accurate conclusions by modeling variability in historical controls, patient outcome drifts independent of the tested therapy, and patient selection effects. Simulations compared R2PII and single-arm designs with binary endpoints under realistic parameters (e.g. alpha = beta = 0.10, historical control success rate = 20%, target success rate = 40%). Results: In the absence of variability in historical controls, estimated false positive and negative rates in both designs mirror the designated specifications. However, even in the presence of a modest drift effect in the population (mean 5% absolute shift in true control success rate), the false positive rate in single-arm designs is inflated two to three fold (to 20%-30%), while the R2PII retains the desired error rates. Greater confidence in historical controls in the single-arm design corrects only a small portion of the deviations. Increasing the sample size in each trial inflates the false positive error rate further to as much as 50%. Varying several sets of parameters gave similar results. Conclusions: In the presence of variability in historical controls, patient drift and/or selection effects, the false positive error rate of a single arm design is unacceptably high. In contrast, the R2PII design is reliable and robust despite the complexities in patient outcome drift and selection effects, and variability in historical control success rates. Given the rapid improvements in outcomes of many tumor types, the R2PII design should be the preferred method to evaluate novel agents in oncology in spite of the associated costs and the use of a reference control arm. No significant financial relationships to disclose.

4054 Background: In treatment trials of patients with metastatic colorectal cancer (mCRC), KRAS mutation status of tumor samples has been retrospectively demonstrated to be predictive of treatment benefit. Historically, clinical trials have not required tissue samples to be tested for KRAS mutation status as a condition of enrollment. Therefore, KRAS analyses have been based on available tissue samples representing only a portion of patients retrospectively analyzed for KRAS status and correlated with treatment end- points. Methods: A weighted analysis of pooled data was performed using six recently presented or published clinical trials of targeted therapy in mCRC which tested for the association of KRAS status with Progression Free Survival (PFS). The goal of the analysis was to determine whether there is a significant difference in PFS between the intention to treat (ITT) population and KRAS population in both the treatment and control arms. Results: The total ITT population of the pooled studies is 3864, and for the total KRAS population, 2295; a 59.4% retrieval rate (range 28–92%) for tissue samples available for KRAS analysis. The weighted Δ PFS across all arms between the ITT population and the KRAS population was 0.2 months with a range of 0–0.7 months. Of the 12 subgroups (6 control and 6 treatment arms), five had no difference in PFS between ITT and KRAS evaluable populations at all, and two additional subgroups demonstrated a difference PFS of only 0.1 months. The two studies with the lowest tissue retrieval rates (28% and 45%) had the largest Δ PFS. Conclusions: There is no meaningful difference in the PFS between the ITT and KRAS populations based on our analysis of pooled data. The difference in PFS was greatest in the two studies with the lowest rate of retrieval of tissue samples for KRAS testing. As such, subgroup analysis is better able to estimate and reflect the ITT population if a higher percentage of samples is able to be obtained. Further, our results suggest that there is not an inherent systemic bias influencing any potentially observed differences in PFS. Tissue samples should be required for all patients entering a clinical trial to avoid this issue and to make retrospective analysis more valid. [Table: see text]

4045 Background: Our group previously reported on patient (Pt) recollections of adjuvant therapy (AT) for colon cancer and their grading of medical oncologists (MO) regarding various aspects of care. Overall, MO were highly rated, but grades for presenting information were lower, and patient expectations about side effects often did not match experiences. To further examine the Pt experience with AT, a prospective study was launched in Feb 2008. Methods: Pts with Stage II/III colon cancer about to begin or within 4 months of starting AT were recruited for a 4-part survey regarding sources and quality of treatment information and their experiences with AT. The survey also asked Pts to provide a grade (A-F) for their MO in 8 areas. Results: 85 Pts (71% female, 79% Stage III, median age 52 years) completed Part 1 of the survey. 93% stated that their MO explained the risks and benefits of AT. Of those, 92% stated they understood this information completely or almost completely (3 or 4 on a 0–4 scale) and 79% received numerical estimates of recurrence risk with and without treatment. When questioned about the potential absolute benefit of AT, 26% of Pts who received numerical estimates “had no idea” and other answers ranged from 3% to 100% for recurrence risk. Pt grade point averages for their MO ranged from 3.0 to 3.6 ( Table 1 ). As in the prior survey, expectations about side effects frequently did not accurately reflect experiences. For example, 54% of Pts expected alopecia but only 5% experienced it to a significant degree. 84% of Pts also sought information from websites, and 87% rated this as helpful and valuable (3 or 4 on a 0–4 scale). Conclusions: Pts are generally satisfied with their MO but less so with the presentation of treatment-related information and thus frequently consult additional resources, such as cancer information websites. This suggests an opportunity for improved information delivery within oncology offices and via the Internet. [Table: see text] [Table: see text]

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.

4025 Background: Cumulative sNT is the dose-limiting toxicity of oxaliplatin which commonly leads to early discontinuation of oxaliplatin-based therapy in the palliative and adjuvant setting. We recently demonstrated the protective effect of CaMg against oxaliplatin-induced sNT as assessed by NCI-CTC (Nikcevich ASCO 2008). It is unclear, though, if CaMg reduced acute and/or chronic, cumulative sNT. Methods: 104 pts with colon cancer undergoing adjuvant therapy with FOLFOX were randomized to IV CaMg (1g calcium gluconate plus 1g magnesium sulfate pre- and post-oxaliplatin) or placebo (PL) in a double-blinded manner. NCI-CTC, an oxaliplatin-specific sNT scale and patient-reported outcome (PRO) questionnaires were used to differentially assess the effect of CaMg on acute (effect on sNT on days 1–4 after oxaliplatin) and chronic sNT (area between curves over whole course of therapy). Results: A total of 102 pts (50 CaMg, 52 PL; 96 mFOLFOX6, 6 FOLFOX4) were available for analysis. Apart from a strong reduction in muscle cramps with CaMg (p=0.002), no difference was found between CaMg and PL in PRO with regard to items reflecting acute sNT (e.g. sensitivity to cold, swallowing of cold liquids, throat discomfort) on days 1–4 after oxaliplatin of any treatment cycle. In contrast, CaMg was able to significantly reduce cumulative sNT in form of numbness in fingers (p=0.02), impaired ability to button shirts (p=0.05), tingling in fingers (p=0.06), and muscle cramps over the course of therapy (p=0.01). Conclusions: In our phase III, placebo-controlled trial, CaMg was able to significantly reduce chronic, cumulative sNT related to oxaliplatin as evaluated by specific PRO questionnaires. No effect was noted on phenomena associated with acute sNT. CaMg can be recommended as neuroprotectant against oxaliplatin-related chronic sNT, oxaliplatin's dose-limiting toxicity. [Table: see text]