Sorafenib for Advanced and Refractory Desmoid Tumors.

BACKGROUND: Desmoid tumors (also referred to as aggressive fibromatosis) are connective tissue neoplasms that can arise in any anatomical location and infiltrate the mesentery, neurovascular structures, and visceral organs. There is no standard of care. METHODS: In this double-blind, phase 3 trial, we randomly assigned 87 patients with progressive, symptomatic, or recurrent desmoid tumors to receive either sorafenib (400-mg tablet once daily) or matching placebo. Crossover to the sorafenib group was permitted for patients in the placebo group who had disease progression. The primary end point was investigator-assessed progression-free survival; rates of objective response and adverse events were also evaluated. RESULTS: With a median follow-up of 27.2 months, the 2-year progression-free survival rate was 81% (95% confidence interval [CI], 69 to 96) in the sorafenib group and 36% (95% CI, 22 to 57) in the placebo group (hazard ratio for progression or death, 0.13; 95% CI, 0.05 to 0.31; P<0.001). Before crossover, the objective response rate was 33% (95% CI, 20 to 48) in the sorafenib group and 20% (95% CI, 8 to 38) in the placebo group. The median time to an objective response among patients who had a response was 9.6 months (interquartile range, 6.6 to 16.7) in the sorafenib group and 13.3 months (interquartile range, 11.2 to 31.1) in the placebo group. The objective responses are ongoing. Among patients who received sorafenib, the most frequently reported adverse events were grade 1 or 2 events of rash (73%), fatigue (67%), hypertension (55%), and diarrhea (51%). CONCLUSIONS: Among patients with progressive, refractory, or symptomatic desmoid tumors, sorafenib significantly prolonged progression-free survival and induced durable responses. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT02066181 .).

Phase I/II Randomized Trial of Sorafenib and Bevacizumab as First-Line Therapy in Patients with Locally Advanced or Metastatic Hepatocellular Carcinoma: North Central Cancer Treatment Group Trial N0745 (Alliance).

BACKGROUND: Angiogenesis has been a major target of novel drug development in hepatocellular carcinoma (HCC). It is hypothesized that the combination of two antiangiogenic agents, sorafenib and bevacizumab, will provide greater blockade of angiogenesis. OBJECTIVE: To determine the optimal dose, safety, and effectiveness of dual anti-angiogenic therapy with sorafenib and bevacizumab in patients with advanced HCC. PATIENTS AND METHODS: Patients with locally advanced or metastatic HCC not amenable for surgery or liver transplant were eligible. The phase I starting dose level was bevacizumab 1.25 mg/kg day 1 and 15 plus sorafenib 400 mg twice daily (BID) days 1-28. In the phase II portion, patients were randomized to receive bevacizumab and sorafenib at the maximum tolerated dose (MTD) or sorafenib 400 mg BID. RESULTS: Seventen patients were enrolled in the phase I component. Dose-limiting toxicities included grade 3 hand/foot skin reaction, fatigue, hypertension, alanine/aspartate aminotransferase increase, dehydration, hypophosphatemia, creatinine increase, hypoglycemia, nausea/vomiting, and grade 4 hyponatremia. Seven patients were enrolled in the phase II component at the MTD: sorafenib 200 mg BID days 1-28 and bevacizumab 2.5 mg/kg every other week; 57% (4/7) had grade 3 AEs at least possibly related to treatment. No responses were observed in the phase II portion. Estimated median time to progression and survival were 8.6 months (95% CI: 0.4-16.3) and 13.3 months (95% CI 4.4 - not estimable), respectively. CONCLUSIONS: The MTD of the combination is sorafenib 200 mg twice daily on days 1-28 plus bevacizumab 2.5 mg/kg on days 1 and 15 of a 28-day cycle. In the phase II portion of the trial, concerns regarding excessive toxicity, low efficacy, and slow enrollment led to discontinuation of the trial. (Clinical Trials ID: NCT00867321.).

Patient and tumor characteristics and BRAF and KRAS mutations in colon cancer, NCCTG/Alliance N0147.

BACKGROUND: KRAS and BRAF (V600E) mutations are important predictive and prognostic markers, respectively, in colon cancer, but little is known about patient and clinical factors associated with them. METHODS: Two thousand three hundred twenty-six of 3397 patients in the N0147 phase III adjuvant trial for stage III colon cancer completed a patient questionnaire. Primary tumors were assessed for KRAS and BRAF (V600E) mutations and defective mismatch repair (dMMR) status. Logistic regression models and categorical data analysis were used to identify associations of patient and tumor characteristics with mutation status. All statistical tests were two-sided. RESULTS: KRAS (35%) and BRAF (V600E) (14%) mutations were nearly mutually exclusive. KRAS mutations were more likely to be present in patients without a family history of colon cancer and never smokers. Tumors with KRAS mutations were less likely to have dMMR (odds ratio [OR] = 0.21; 95% confidence interval [CI] = 0.15 to 0.31; P < .001) and high-grade histology (OR = 0.73; 95% CI = 0.59 to 0.92; P < .001) but were more often right-sided. Among KRAS-mutated tumors, those with a Gly13Asp mutation tended to have dMMR and high-grade histology. Tumors with BRAF (V600E) mutations were more likely to be seen in patients who were aged 70 years or older (OR = 3.33; 95% CI = 2.50 to 4.42; P < .001) and current or former smokers (OR = 1.64; 95% CI = 1.26 to 2.14; P < .001) but less likely in non-whites and men. Tumors with BRAF (V600E) mutations were more likely to be right-sided and to have four or more positive lymph nodes, high-grade histology, and dMMR. CONCLUSIONS: Specific patient and tumor characteristics are associated with KRAS and BRAF (V600E) mutations.

KRAS codon 12 and 13 mutations in relation to disease-free survival in BRAF-wild-type stage III colon cancers from an adjuvant chemotherapy trial (N0147 alliance).

PURPOSE: We examined the prognostic impact of specific KRAS mutations in patients with stage III colon adenocarcinoma receiving adjuvant FOLFOX alone or combined with cetuximab in a phase III trial (N0147). Analysis was restricted to BRAF-wild-type tumors, because BRAF mutation was associated with poor prognosis, and BRAF and KRAS mutations are mutually exclusive. EXPERIMENTAL DESIGN: The seven most common KRAS mutations in codon 12 and codon 13 were examined in 2,478 BRAF-wild-type tumors. Because KRAS mutations in codon 12 (n = 779) or 13 (n = 220) were not predictive of adjuvant cetuximab benefit, study arms were pooled for analysis. Disease-free survival (DFS) was evaluated by HRs using Cox models. RESULTS: KRAS mutations in codon 12 (multivariate HR, 1.52; 95% confidence interval, CI, 1.28-1.80; P < 0.0001) or codon 13 (multivariate HR, 1.36; 95% CI, 1.04-1.77; P = 0.0248) were significantly associated with shorter DFS compared with patients with wild-type KRAS/BRAF tumors, independent of covariates. KRAS codon 12 mutations were independently associated with proficient mismatch repair (P < 0.0001), proximal tumor site (P < 0.0001), low grade, age, and sex, whereas codon 13 mutations were associated with proximal site (P < 0.0001). CONCLUSION: KRAS mutations in either codon 12 or 13 are associated with inferior survival in patients with resected stage III colon cancer. These data highlight the importance of accurate molecular characterization and the significant role of KRAS mutations in both codons in the progression of this malignancy in the adjuvant setting. Clin Cancer Res; 20(11); 3033-43. ©2014 AACR.

Comparison of FOLFIRI with or without cetuximab in patients with resected stage III colon cancer; NCCTG (Alliance) intergroup trial N0147.

BACKGROUND: Two arms with FOLFIRI, with or without cetuximab, were initially included in the randomized phase III intergroup clinical trial NCCTG (North Central Cancer Treatment Group) N0147. When other contemporary trials demonstrated no benefit to using irinotecan as adjuvant therapy, the FOLFIRI-containing arms were discontinued. We report the clinical outcomes for patients randomized to FOLFIRI with or without cetuximab. PATIENTS AND METHODS: After resection, patients were randomized to 12 biweekly cycles of FOLFIRI, with or without cetuximab. KRAS (Kirsten rat sarcoma viral oncogene homolog) mutation status was retrospectively determined in a central lab. The primary end point was disease-free survival (DFS). Secondary end points included overall survival (OS) and toxicity. RESULTS: One hundred and six patients received FOLFIRI and 40 received FOLFIRI plus cetuximab. Median follow-up was 5.95 years (range, 0.1-7.0 years). The addition of cetuximab showed a trend toward improved DFS (hazard ratio [HR], 0.53; 95% CI, 0.26-1.1; P = .09) and OS (HR, 0.45; 95% CI, 0.17-1.16; P = .10) in the overall group, regardless of KRAS status, and in patients with wild type KRAS. Grade ≥ 3 nonhematologic adverse effects were significantly increased in the cetuximab versus FOLFIRI-alone arm (68% vs. 46%; P = .02). Adjuvant FOLFIRI resulted in a 3-year DFS less than that expected for FOLFOX. CONCLUSION: In this small randomized subset of patients with resected stage III colon cancer, the addition of cetuximab to FOLFIRI was associated with a nonsignificant trend toward improved DFS and OS. Nevertheless, considering the limitations of this analysis, FOLFOX without the addition of a biologic agent remains the standard of care for adjuvant therapy in resected stage III colon cancer.

Prognostic impact of deficient DNA mismatch repair in patients with stage III colon cancer from a randomized trial of FOLFOX-based adjuvant chemotherapy.

PURPOSE: The association of deficient DNA mismatch repair (dMMR) with prognosis in patients with colon cancer treated with adjuvant fluorouracil, leucovorin, and oxaliplatin (FOLFOX) chemotherapy remains unknown. PATIENTS AND METHODS: Resected, stage III colon carcinomas from patients (N = 2,686) randomly assigned to FOLFOX ± cetuximab (North Central Cancer Treatment Group N0147 trial) were analyzed for mismatch repair (MMR) protein expression and mutations in BRAF(V600E) (exon 15) and KRAS (codons 12 and 13). Association of biomarkers with disease-free survival (DFS) was determined using Cox models. A validation cohort (Cancer and Leukemia Group B 88903 trial) was used. RESULTS: dMMR was detected in 314 (12%) of 2,580 tumors, of which 49.3% and 10.6% had BRAF(V600E) or KRAS mutations, respectively. MMR status was not prognostic overall (adjusted hazard ratio [HR], 0.82; 95% CI, 0.64 to 1.07; P = .14), yet significant interactions were found between MMR and primary tumor site (P(interaction) = .009) and lymph node category (N1 v N2; P(interaction) = .014). Favorable DFS was observed for dMMR versus proficient MMR proximal tumors (HR, 0.71; 95% CI, 0.53 to 0.94; P = .018) but not dMMR distal tumors (HR, 1.71; 95% CI, 0.99 to 2.95; P = .056), adjusting for mutations and covariates. Any survival benefit of dMMR was lost in N2 tumors. Mutations in BRAF(V600E) (HR, 1.37; 95% CI, 1.08 to 1.70; P = .009) or KRAS (HR, 1.44; 95% CI, 1.21 to 1.70; P < .001) were independently associated with worse DFS. The observed MMR by tumor site interaction was validated in an independent cohort of stage III colon cancers (P(interaction) = .037). CONCLUSION: The prognostic impact of MMR depended on tumor site, and this interaction was validated in an independent cohort. Among dMMR cancers, proximal tumors had favorable outcome, whereas distal or N2 tumors had poor outcome. BRAF or KRAS mutations were independently associated with adverse outcome.

Effect of oxaliplatin, fluorouracil, and leucovorin with or without cetuximab on survival among patients with resected stage III colon cancer: a randomized trial.

CONTEXT: Leucovorin, fluorouracil, and oxaliplatin (FOLFOX) is the standard adjuvant therapy for resected stage III colon cancer. Adding cetuximab to FOLFOX benefits patients with metastatic wild-type KRAS but not mutated KRAS colon cancer. OBJECTIVE: To assess the potential benefit of cetuximab added to the modified sixth version of the FOLFOX regimen (mFOLFOX6) in patients with resected stage III wild-type KRAS colon cancer. DESIGN, SETTING, AND PARTICIPANTS: A randomized trial of 2686 patients aged 18 years or older at multiple institutions across North America enrolled following resection and informed consent between February 10, 2004, and November 25, 2009. The primary randomized comparison was 12 biweekly cycles of mFOLFOX6 with and without cetuximab. KRAS mutation status was centrally determined. The trial was halted after a planned interim analysis of 48% of predicted events (246/515) occurring in 1863 (of 2070 planned) patients with tumors having wild-type KRAS. A total of 717 patients with mutated KRAS and 106 with indeterminate KRAS were accrued. The 2070 patients with wild-type KRAS provided 90% power to detect a hazard ratio (HR) of 1.33 (2-sided α = .05), with planned interim efficacy analyses after 25%, 50%, and 75% of expected relapses. MAIN OUTCOME MEASURES: Disease-free survival in patients with wild-type KRAS mutations. Secondary end points included overall survival and toxicity. RESULTS: Median (range) follow-up was 28 (0-68) months. The trial demonstrated no benefit when adding cetuximab. Three-year disease-free survival for mFOLFOX6 alone was 74.6% vs 71.5% with the addition of cetuximab (HR, 1.21; 95% CI, 0.98-1.49; P = .08) in patients with wild-type KRAS, and 67.1% vs 65.0% (HR, 1.12; 95% CI, 0.86-1.46; P = .38) in patients with mutated KRAS, with no significant benefit in any subgroups assessed. Among all patients, grade 3 or higher adverse events (72.5% vs 52.3%; odds ratio [OR], 2.4; 95% CI, 2.1-2.8; P < .001) and failure to complete 12 cycles (33% vs 23%; OR, 1.6; 95% CI, 1.4-1.9; P < .001) were significantly higher with cetuximab. Increased toxicity and greater detrimental differences in all outcomes were observed in patients aged 70 years or older. CONCLUSION: Among patients with stage III resected colon cancer, the use of cetuximab with adjuvant mFOLFOX6 compared with mFOLFOX6 alone did not result in improved disease-free survival. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00079274.

Hepatic arterial infusion and systemic chemotherapy after multiple metastasectomy in patients with colorectal carcinoma metastatic to the liver: a North Central Cancer Treatment Group (NCCTG) phase II study, 92-46-52.

BACKGROUND: Patients with multiple liver metastases from colorectal cancer are at high risk of recurrence after resection. Hepatic artery infusion (HAI) alternating with systemic therapy after surgical resection may improve survival after surgery. METHODS: Patients with liver-only metastases from colorectal cancer amenable to resection/cryoablation were eligible. Previous adjuvant chemotherapy for a completely resected primary tumor was allowed. Alternating courses of HAI and systemic therapy included floxuridine (FUDR) by HAI. Systemic chemotherapy consisted of bolus leucovorin (LV) plus 5-fluorouracil (5-FU). RESULTS: Forty-nine patients had complete resection of their liver metastases, with 44% having more than 4 hepatic metastases and 78% having bilobar disease. Thirty-six patients had HAI FUDR alternating with systemic therapy. Patients received a median of 3.5 cycles (range, 1-4) and 3 cycles (range, 0-6) of therapy with HAI FUDR and systemic therapy, respectively. At the time of final analysis the estimated median disease-free survival and hepatic disease-free survival was 1.2 years (95% confidence interval [CI], 0.9-2.1) and 1.8 years (95% CI, 1.8-not available), respectively. Eleven patients (31%) were alive at this writing. All surviving patients had a minimum of 5.5 years of follow-up. CONCLUSION: This trial of adjuvant chemotherapy in patients who underwent complete resection with unfavorable characteristics demonstrates apparent improvement in outcome compared with historical series treated with surgery alone. However the results of this trial and other randomized trials of HAI do not appear to support its use at this time because of the development of more effective systemic options.

Alternating systemic and hepatic artery infusion therapy for resected liver metastases from colorectal cancer: a North Central Cancer Treatment Group (NCCTG)/ National Surgical Adjuvant Breast and Bowel Project (NSABP) phase II intergroup trial, N9945/CI-66.

PURPOSE Prior trials have shown that surgery followed by hepatic artery infusion (HAI) of floxuridine (FUDR) alternating with systemic fluorouracil improves survival rates. Oxaliplatin combined with capecitabine has demonstrated activity in advanced colorectal cancer. Based on this observation a trial was conducted to assess the potential benefit of systemic oxaliplatin and capecitabine alternating with HAI of FUDR. The primary end point was 2-year survival. PATIENTS AND METHODS Patients with liver-only metastases from colorectal cancer amenable to resection or cryoablation were eligible. HAI and systemic therapy was initiated after metastasectomy. Alternating courses of HAI consisted of 0.2 mg/m(2)/d FUDR and dexamethasone, day 1 through 14 weeks 1 and 2. Systemic therapy included oxaliplatin 130 mg/m(2) day 1 with capecitabine at 1,000 mg/m(2) twice daily, days 1 through 14, weeks 4 and 5. Two additional 3-week courses of systemic therapy were given. Capecitabine was reduced to 850 mg/m(2) twice daily after interim review of toxicity. Results Fifty-five of 76 eligible patients were able to initiate protocol-directed therapy and completed median of six cycles (range, one to six). Three postoperative or treatment-related deaths were reported. Overall, 88% of evaluable patients were alive at 2 years. With a median follow-up of 4.8 years, a total of 30 patients have had disease recurrence, 11 involving the liver. Median disease-free survival was 32.7 months. CONCLUSION Alternating HAI of FUDR and systemic capecitabine and oxaliplatin met the prespecified end point of higher than 85% survival at 2 years and was clinically tolerable. However, the merits of this approach need to be established with a phase III trial.

Phase III noninferiority trial comparing irinotecan with oxaliplatin, fluorouracil, and leucovorin in patients with advanced colorectal carcinoma previously treated with fluorouracil: N9841.

PURPOSE: The primary goal of this multicenter phase III trial was to determine whether overall survival (OS) of fluorouracil (FU) -refractory patients was noninferior when treated with second-line infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX4; arm B) versus irinotecan (arm A). Cross-over to the other treatment on disease progression was mandated. PATIENTS AND METHODS: Patients who experienced treatment failure with one prior FU-based therapy and had not received prior irinotecan or oxaliplatin, either for metastatic disease or within 6 months of adjuvant FU therapy, were randomly assigned to arm A (irinotecan 350 or 300 mg/m(2) every 3 weeks) or arm B (FOLFOX4). RESULTS: A total of 491 patients were randomly assigned (arm A, n = 245; arm B, n = 246); 288 (59%) had experienced treatment failure with FU for metastatic colorectal cancer. Two hundred twenty-seven patients (46%) received protocol-mandated third-line therapy (arm A, 43%; arm B, 57%). Median survival was 13.8 months (95% CI, 12.2 to 15.0 months) for initial treatment with FOLFOX4 and 14.3 months (95% CI, 12.0 to 15.9 months) for irinotecan (P = .38; hazard ratio = 0.92; 95% CI, 0.8 to 1.1). Response rates (RR; 28% v 15.5%; P = .0009) and time to progression (TTP; 6.2 v 4.4 months; P = .0009) were significantly superior with FOLFOX4. In the nonrandom subset of patients who crossed over, RR and TTP improvements with FOLFOX4 continued into third-line treatment. Irinotecan therapy was associated with more grade 3 nausea, vomiting, diarrhea, and febrile neutropenia; FOLFOX4 was associated with more neutropenia and paresthesias. CONCLUSION: In patients who experienced treatment failure with front-line FU therapy, OS does not significantly differ whether second-line therapy begins with irinotecan or FOLFOX4. FOLFOX4 produces higher RR and longer TTP. Both arms had notable OS in patients who experienced treatment failure with first-line FU therapy.

Pemetrexed and oxaliplatin for metastatic colorectal cancer: results of a phase I Mayo Cancer Center Research Consortium trial, MC0248.

PURPOSE: Pemetrexed, an antifolate involved in purine and pyrimidine formation, is a potential alternative to fluoropyrimidines in the treatment of colorectal cancer. A phase I trial was performed to establish the maximum tolerated dose (MTD) of pemetrexed and oxaliplatin when B(12) and folate supplementation is used. PATIENTS AND METHODS: Patients with metastatic colorectal cancer received folate (> 350 microg) daily and vitamin B(12) (1000 microg) every 9 weeks starting 7 days before chemotherapy. Pemetrexed over 10 minutes and oxaliplatin over 2 hours were given every 3 weeks in escalating dose cohorts. RESULTS: Twenty-two patients were entered on 6 dose levels. The MTD was established at the highest dose level, pemetrexed 900 mg/m(2) and oxaliplatin 130 mg/m(2). Toxicities related to treatment at the MTD included grade 3 neutropenia and thrombocytopenia. For all dose levels combined, grade 3/4 toxicities included hematologic, neurologic, and gastrointestinal. Nine of 21 evaluable patients responded overall (response rate, 43%). The time to tumor progression was 11.9 months. CONCLUSION: The MTD was determined to be pemetrexed 900 mg/m(2) and oxaliplatin 130 mg/m(2) every 21 days when folate and B (12) supplementation are used. Because of the observed tolerability and activity of this regimen, further evaluation is warranted.

Randomized clinical trial of high-dose levamisole combined with 5-fluorouracil and leucovorin as surgical adjuvant therapy for high-risk colon cancer.

BACKGROUND: Levamisole combined with 5-fluorouracil (5-FU) was previously shown to significantly reduce tumor relapses and improve patient survival when given postoperatively in patients with resected stage III colon cancer. Laboratory investigations subsequently documented a direct dose-dependent enhancement of 5-FU cytotoxicity with increasing concentrations of levamisole against human cancer cell lines. A clinical trial was designed to test the value of levamisole given at its maximum tolerated dose in combination with 5-FU-based chemotherapy. PATIENTS AND METHODS: Eight hundred seventy-eight patients who had undergone complete surgical resection of high-risk stage II/III colon cancer were stratified by known prognostic factors and randomized to receive 1 of 2 treatment regimens: standard-dose levamisole combined with 5-FU and leucovorin; or high-dose levamisole combined with the same chemotherapy. Serum neopterin was monitored in a cohort of patients to evaluate immune function. RESULTS: Severe vomiting and neurologic side effects required reduction in the dose of levamisole that could be safely administered on the high-dose levamisole regimen. There were no significant differences in disease-free survival, overall survival, or levels of serum neopterin between the treatment regimens. CONCLUSION: It was not possible to improve the efficacy of surgical adjuvant chemotherapy for patients with high-risk colon cancer by giving levamisole at its maximum tolerated dose in combination with 5-FU and leucovorin. High rates of severe gastrointestinal and neurologic side effects were observed with the high-dose levamisole regimen.

Prognostic value of proliferation, apoptosis, defective DNA mismatch repair, and p53 overexpression in patients with resected Dukes' B2 or C colon cancer: a North Central Cancer Treatment Group Study.

PURPOSE: Molecular studies of colon cancer have provided insights into pathogenesis, yet it is unclear how important these markers are in predicting prognosis. This study investigated the prognostic significance of TUNEL, bcl-2, p53, proliferation marker Ki-67 and DNA mismatch repair (MMR) status in patients with Dukes' stage B2 and C colorectal adenocarcinomas. PATIENTS AND METHODS: Tumor tissue from 366 patients (75% Dukes' C, 25% Dukes' B2) from four randomized North Central Cancer Treatment Group phase III surgical adjuvant trials were used. Eighty-one percent of patients received adjuvant treatment, which was primarily fluorouracil (FU) based (90%). Tumor location was predominantly (87%) the colon. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), Ki-67, p53, bcl-2, and MMR were assayed using immunohistochemistry. Stage, grade, MMR, Ki-67, and previously determined flow cytometry markers (ploidy and S phase) were explored for associations with each other and with overall survival (OS) and disease-free survival (DFS). RESULTS: Univariately, stage B2, low grade, diploid, Ki-67 more than 27%, normal p53, and FU-based adjuvant treatment were significantly associated with improved OS and DFS (P <.05). After adjusting for stage, grade, and ploidy in multivariate analysis, Ki-67 remained significantly related to both OS and DFS (P <.01). Active FU-based adjuvant treatment was significant only for OS in this multivariate model. Neither bcl-2 nor TUNEL were significant. CONCLUSION: This retrospective study indicates that Ki-67 and ploidy may have stronger prognostic impact on OS and DFS than other parameters investigated after adjusting for stage and tumor grade. Prospective studies to elucidate the mechanism and prognostic significance of these findings are necessary.

Investigation of the prognostic and predictive value of thymidylate synthase, p53, and Ki-67 in patients with locally advanced colon cancer.

PURPOSE: To evaluate the value of thymidylate synthase (TS), Ki-67, and p53 as prognostic markers in patients with Dukes' B2 and C colon carcinoma. METHODS: We conducted a retrospective analysis to evaluate the prognostic value of TS, Ki-67, and p53 in 465 patients with Dukes' B2 (220 patients) or Dukes' C (245 patients) colon carcinoma. Patients represent a nonrandom subset obtained from five randomized phase III trials and were treated with either surgery alone (151 patients) or surgery plus fluorouracil-based chemotherapy (314 patients). All three markers were assayed using immunohistochemical techniques. RESULTS: With a minimum follow-up of 5 years, our retrospective analysis failed to demonstrate a consistent and significant association between TS, Ki-67, or p53 and either disease-free survival or overall survival. Exploratory analyses did not reveal a convincing explanation for these results that are in conflict with the published literature. Notable interactions were observed. In particular, high Ki-67 levels were associated with increased (decreased) survival in patients with low (high) TS intensity. Patients whose tumors stained positively for p53 seemed to benefit substantially from the use of adjuvant chemotherapy compared with those who were not treated (P =.05). CONCLUSION: This retrospective investigation failed to demonstrate a significant association between TS, Ki-67, or p53 staining and clinical outcome.