Reevaluating Disease-Free Survival as an Endpoint vs Overall Survival in Stage III Adjuvant Colon Cancer Trials

Results from the UNITED study: a multicenter study validating the prognostic effect of the tumor-stroma ratio in colon cancer

BACKGROUND

The TNM (tumor-node-metastasis) Evaluation Committee of Union for International Cancer Control (UICC) and College of American Pathologists (CAP) recommended to prospectively validate the cost-effective and robust tumor-stroma ratio (TSR) as an independent prognostic parameter, since high intratumor stromal percentages have previously predicted poor patient-related outcomes.

PATIENTS AND METHODS

The 'Uniform Noting for International application of Tumor-stroma ratio as Easy Diagnostic tool' (UNITED) study enrolled patients in 27 participating centers in 12 countries worldwide. The TSR, categorized as stroma-high (>50%) or stroma-low (≤50%), was scored through standardized microscopic assessment by certified pathologists, and effect on disease-free survival (DFS) was evaluated with 3-year median follow-up. Secondary endpoints were benefit assessment of adjuvant chemotherapy (ACT) and overall survival (OS).

RESULTS

A total of 1537 patients were included, with 1388 eligible stage II/III patients curatively operated between 2015 and 2021. DFS was significantly shorter in stroma-high (n = 428) than in stroma-low patients (n = 960) (3-year rates 70% versus 83%; P < 0.001). In multivariate analysis, TSR remained an independent prognosticator for DFS (P < 0.001, hazard ratio 1.49, 95% confidence interval 1.17-1.90). As secondary outcome, DFS was also worse in stage II and III stroma-high patients despite adjuvant treatment (3-year rates stage II 73% versus 92% and stage III 66% versus 80%; P = 0.008 and P = 0.011, respectively). In stage II patients not receiving ACT (n = 322), the TSR outperformed the American Society of Clinical Oncology (ASCO) criteria in identifying patients at risk of events (event rate 21% versus 9%), with a higher discriminatory 3-year DFS rate (stroma-high 80% versus ASCO high risk 91%). A trend toward worse 5-year OS in stroma-high was noticeable (74% versus 83% stroma-low; P = 0.102).

CONCLUSION

The multicenter UNITED study unequivocally validates the TSR as an independent prognosticator, confirming worse outcomes in stroma-high patients. The TSR improved current selection criteria for patients at risk of events, and stroma-high patients potentially experienced chemotherapy resistance. TSR implementation in pathology diagnostics and international guidelines is highly recommended as aid in personalized treatment.

Prognostic Implications of Endoscopic Obstruction in Patients with Pathological Stage II Colon Cancers: a Single-Center Retrospective Cohort Study

BACKGROUND

The prognostic effect of endoscopic obstruction (eOB) on the survival of stage II colon cancer patients and the role of eOB in guiding postoperative adjuvant chemotherapy of stage II colon cancer are little known.

METHODS

In this retrospective, single-center cohort study, patients who had undergone curative surgery and preoperative colonoscope for stage II colon carcinoma were included. The eOB was defined as severe luminal colon obstruction that prevented the standard colonoscope from passing beyond the tumor. The association between eOB and stage II colon cancer survival and the predictive role of eOB for adjuvant chemotherapy were evaluated using multivariate Cox regression analysis.

RESULTS

Of 1102 included patients, 616 (55.9%) had eOB and 486 (44.1%) had no eOB. The median follow-up was 49 months (interquartile range, 38-68 months). Kaplan-Meier curves showed that patients with eOB had poor 5-year overall survival (OS; 85.3% vs. 95.3%, p < 0.001) compared to patients without eOB. Five-year disease-free survival (DFS; 78.5% vs. 87.6%, p = 0.004) was also poor in these patients. Multivariate analysis demonstrated eOB was a significant prognostic factor for poor OS (hazard ratio [HR] = 2.531, p < 0.001), but not for DFS (p = 0.081). Even when patients with clinical colonic obstruction were excluded from the population with eOB, the worse OS (HR = 2.262, p = 0.001) was observed. The OS and DFS of eOB patients improved slightly after adjuvant chemotherapy, but there was no statistical significance.

CONCLUSIONS

Stage II colon cancer patients with eOB have a poor prognosis. However, whether eOB can guide adjuvant chemotherapy still needs further study.

End of induction positron emission tomography complete response (PET-CR) as a surrogate for progression-free survival in previously untreated follicular lymphoma

Progression-free survival (PFS) has been the regulatory primary end-point for recent phase III trials in first-line follicular lymphoma (FL), but requires prolonged follow-up. Complete response (CR) at 30 months after initiation of induction treatment was validated as surrogate end-point for PFS. Our objective was to further evaluate surrogacy of CR measured by [¹⁸ F] fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging at the end of induction (EoI). Individual patient data were analysed from 1505 patients from five randomized trials. Trial-level surrogacy examining the association between treatment effects on EoI-PET-CR and PFS was evaluated using linear regression ( R WLS 2 $$ {R}_{\mathrm{WLS}}^2 $$ ) and bivariate Copula ( R Copula 2 $$ {R}_{\mathrm{Copula}}^2 $$ ) models. Although EoI-PET-CR strongly predicted PFS at a prognostic level, the trial-level assessment did not show strong correlation ( R WLS 2 = 0.56 $$ {R}_{\mathrm{WLS}}^2=0.56 $$ , confidence interval [CI]: 0.20-0.88; R Copula 2 = 0.35 $$ {R}_{\mathrm{Copula}}^2=0.35 $$ , CI: 0.0-0.82). The high uncertainty in estimation was possibly due to the small number of trials and the population of patients with available PET data. Maintenance therapy affecting PFS beyond induction treatment, but not EoI-PET-CR end-point, may have distorted the association between treatment effects. However, there will probably be a number of additional trials approaching completion with available PET response data. Refined evaluation of PET-CR based surrogate end-points is still warranted.