The Initial Results for a Phase 3 Study of Short-Term Versus Long-Term Chemoradiation Therapy in Locally Advanced Rectal Cancer (STELLAR Trial)

Total Neoadjuvant Therapy (TNT) versus Standard Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Total neoadjuvant therapy (TNT) is a novel approach for locally advanced rectal cancer (LARC), which attempts to deliver both systemic chemotherapy and neoadjuvant chemoradiotherapy prior to surgery. However, its efficacy and safety remain controversial in randomized controlled trials (RCTs). We conducted this meta-analysis to assess such concerns.

MATERIALS AND METHODS

Head-to-head phase II/III RCTs were searched in Embase, PubMed, Web of Science, and the Cochrane Library, as well as other sources. The primary endpoint was pathologic complete response (pCR). Secondary endpoints were disease-free survival (DFS), overall survival (OS), local recurrence-free survival, distant metastasis-free survival, and the R0 resection rate.

RESULTS

Eight phase II/III RCTs involving 2,196 patients with LARC were assessed. The primary analysis demonstrated a statistically significant improvement in the pCR rate for TNT treatment (odds ratio, 1.77; 95% confidence interval [CI], 1.28-2.45; p = .0005). TNT treatment also showed improvements in DFS and OS outcomes compared with standard chemoradiotherapy (hazard ratio [HR], 0.83; 95% CI, 0.72-0.96; p = .03 and HR, 0.88; 95% CI, 0.74-1.05; p = .15). In addition, TNT treatment showed significant efficacy in reducing the risk of distant metastasis (HR, 0.81; 95% CI, 0.68-0.95; p = .012).

CONCLUSION

The overall pCR rate may be improved with TNT compared with standard treatment. The TNT strategy may also improve DFS and OS and reduce the risk of distant metastasis.

IMPLICATIONS FOR PRACTICE

Locally advanced rectal cancer (LARC) is a relatively common disease, with a poor prognosis because of its high metastatic potential. The role of total neoadjuvant therapy (TNT) has always been controversial. This meta-analysis found that TNT in LARC is associated with a significant improvement in overall pathologic complete response rate, disease-free survival, overall survival, and distant metastasis-free survival compared with standard treatment. TNT is a promising strategy for LARC, especially for patients who have little desire for surgery.

New standard in locally advanced rectal cancer

In the following review we intend to ascertain the optimal neoadjuvant therapy in patients with locally advanced rectal cancer. In 2004, a study revealed that chemoradiotherapy (CRT) resulted in better local control when performed preoperatively rather than postoperatively, thus neoadjuvant treatment was established as a standard treatment. Subsequently, the Polish study and the Trans-Tasman Radiation Oncology Group showed no statistically significant difference between concomitant CRT over 5 wk vs short-course radiotherapy (RT). Therefore, both were established as standard neoadjuvant treatments. Later, the Stockholm III study demonstrated that short-course RT had a higher complete pathological response than long-course RT. It also showed that a delay between RT and surgery presented fewer complications. This opened a window of time to provide an early and effective systemic treatment to prevent distant metastases. Studies show that short-course RT plus oxaliplatin-based chemotherapy could achieve this. When comparing this total neoadjuvant treatment (TNT) vs concomitant CRT, the former showed greater complete pathological response and lower acute toxicity. Studies presented during 2020 have also shown the benefits of TNT in terms of complete pathological response, as well as disease and metastasis-free survival. Our review suggests that probably TNT should be the new standard treatment for these patients. However, we will have to wait for the full text publications of these studies to confirm this statement.