Preoperative versus postoperative radiotherapy for rectal cancer in a decision analysis and outcome prediction model

Predictive Significance of Mucinous Histology on Pathologic Complete Response Rate Following Capecitabine-Based Neoadjuvant Chemoradiation in Rectal Cancer: a Comparative Study

INTRODUCTION

Currently, neoadjuvant fluoropyrimidine-based chemoradiation followed by surgery is considered the standard of care for locally advanced rectal cancer. The current study aimed to investigate the predictive significance of mucinous histology on the pathologic complete response rate following neoadjuvant chemoradiation in locally advanced rectal cancer and to propose potential new treatment protocol for this specific histology.

MATERIAL AND METHOD

This retrospective study was conducted on 403 patients with locally advanced (clinically T3-4 and/or N1-2) rectal adenocarcinoma who had been treated at three tertiary academic hospitals between 2010 and 2015. Among those 403 patients, 46 (11%) had mucinous rectal cancer (MRC) and 358 (89%) had non-mucinous rectal cancer (NMRC). All patients underwent neoadjuvant chemoradiation with capecitabine followed by low anterior or abdominoperineal resection.

RESULTS

There were 268 men and 135 women with a median age of 55 years (range, 26-82 years). Patients with MRC were younger (p = 0.002) and presented with a larger tumor size (p < 0.001) and a more advanced tumor stage (p = 0.033) compared to the ones with MNRC. In the univariate analysis, female gender (p = 0.009), distal tumor location (p = 0.035), higher tumor stage (p = 0.049), node positivity (p = 0.001), MRC histology (p = 0.017), and high pretreatment CEA level (p = 0.013) were observed to be predictive of a poor pathologic complete response. However, in the multivariate analysis, tumor stage was the single most predictive factor of response to neoadjuvant chemoradiation.

CONCLUSION

Mucinous adenocarcinoma is a significant predictive factor for poor pathologic complete response to neoadjuvant capecitabine-based chemoradiation in patients with locally advanced rectal cancer. New treatment modality based on biomarkers may be considered in future prospective studies because of MRC poor prognosis. Immunotherapy combined with chemotherapy and/or radiotherapy may be an attractive option because of the tumor microsatellite instability-high status.

Influence of local recurrence on survival in patients with rectal cancer

BACKGROUND

Recent trials on rectal cancer have demonstrated significant improvements in local recurrence without improvements in overall survival. The aim of this paper was to define the influence of local recurrence on survival in a prospective series of patients who underwent R0 or R1 resections for rectal cancer.

METHODS

Patients presenting with rectal cancer from 1996 to 2012 were prospectively audited. The study included patients who underwent an R0 or R1 resection. Local recurrence was defined as cancer regrowth detected in the pelvis regardless of whether or not new metastases were found elsewhere. Kaplan-Meier curves, smoothed hazard functions and Cox models using both time since diagnosis and age as the time scale were used to define the influence of local recurrence on overall survival.

RESULTS

The study involved 483 patients, of mean age 66 years (standard deviation = 13) and a median follow-up of 5.2 years. The results at 5 years were overall survival 71% (95% confidence interval (CI) 66-75), local recurrence 7% (95% CI 5-10) and distant recurrence 18% (95% CI 14-22). Patients diagnosed with local recurrence died faster than patients diagnosed with either distant recurrence or no recurrence, and this was particularly obvious for younger patients (local hazard ratio (HR) 54, 95% CI 12-253 and distant HR19, 95% CI 4-80). Local recurrence that developed early following surgery also had worse survival outcomes.

CONCLUSIONS

Within this cohort of rectal cancer patients, the early development of local recurrence was the single most important indicator of a reduced survival, and carried a worse prognosis than the development of distant metastases alone.