The significance of tumour deposits in rectal cancer after neoadjuvant therapy: a systematic review and meta-analysis.

BACKGROUND

Tumour deposits (TDs) are a poor prognostic marker in colorectal cancer, but their significance after neoadjuvant chemoradiotherapy is less certain because this group of patients is excluded in most studies. Post-treatment TD might even be a sign of tumour response. No previous reviews have assessed outcomes in this group.

MATERIALS AND METHODS

A systematic review and meta-analysis was undertaken according to Preferred Reporting for Systematic Reviews and Meta-Analyses guidelines to determine the relevance of post-treatment TD. Inclusion criteria were studies assessing TD in patients who had undergone pre-operative treatment with radiotherapy and/or chemotherapy and reporting prevalence and survival outcomes. Studies that did not include histological review of cases were excluded.

RESULTS

Eight studies and 1283 patients were included in the review. Prevalence of TDs varied from 11.8% to 44.2% (mean 23.7%), similar to untreated patients. The presence of TDs after chemoradiotherapy was associated with invasion depth, lymph node involvement, perineural invasion and synchronous metastases. The pooled hazard ratio for 5-year adverse disease-free survival was 2.3 (95% confidence interval [CI]: 1.8-2.9), and that for overall survival was 2.5 (95% CI: 1.9-3.3). One study showed a survival benefit with adjuvant therapy in the TD-positive group.

CONCLUSIONS

In analogy with untreated patients, the presence of TDs in patients with rectal cancer after neoadjuvant treatment is associated with advanced disease and a poor outcome.