Why This Study Matters
Colorectal cancer is the third most common cancer and the third leading cause of cancer death worldwide, and rectal cancer accounts for roughly 40% of colorectal malignancies. The standard preoperative approach for locally advanced rectal cancer (LARC) — long-course chemoradiotherapy or short-course radiotherapy followed by total mesorectal excision (TME) — has a persistent completion problem: fewer than half of eligible patients go on to finish the adjuvant chemotherapy originally planned after surgery. That gap has driven interest in front-loading systemic chemotherapy before surgery as part of total neoadjuvant therapy (TNT), with the goal of improving treatment completion, reducing distant metastases, and potentially improving survival.
The STELLAR trial (NCT02533271) was designed to test whether a short-course radiotherapy-based TNT regimen (SCRT-TNT) could match or exceed the outcomes of standard long-course chemoradiotherapy (CRT) in this population. This update reports 5-year outcomes at a median follow-up of 68.7 months.
Study Design
STELLAR is a multicenter, randomized, open-label, phase III trial that assigned patients with distal or middle-third LARC to either SCRT-based TNT or standard long-course CRT. The trial's originally registered primary outcome was 3-year disease-free survival; this article reports an updated 5-year analysis. In the experimental arm, patients received short-course radiotherapy (5 Gy × 5), followed by four cycles of neoadjuvant capecitabine plus oxaliplatin, then TME, then at least two cycles of postoperative adjuvant chemotherapy. In the standard arm, patients received long-course chemoradiotherapy (2 Gy × 25) with concurrent capecitabine, then TME, then at least six cycles of postoperative adjuvant capecitabine. A total of 591 patients were enrolled.
Patient Population
Enrolled patients had biopsy-proven rectal adenocarcinoma classified as locally advanced (AJCC T3, T4, or node-positive), staged by pelvic MRI, with a tumor located within 10 cm of the anal verge and ECOG performance status of 0 or 1. This update focuses specifically on patients with distal or middle-third tumors, per the abstract of the 5-year analysis.
Primary Endpoint Results
The primary endpoint picture is a study in contrasts: SCRT-TNT produced a statistically significant overall survival advantage while missing significance on disease-free survival, the trial's original endpoint framework. That distinction is worth holding onto rather than treating the update as uniformly positive across every outcome measure.
Subgroup Analyses
The abstract reports two prespecified subgroup analyses with exact statistics:
| Subgroup | Outcome | Hazard Ratio (95% CI) | Interpretation |
|---|---|---|---|
| High-risk patients (ESMO criteria) | Overall survival | 0.663 (0.469-0.937) | Improved with SCRT-TNT |
| High-risk patients (ESMO criteria) | Disease-free survival | 0.765 (0.568-1.032) | Nonsignificant trend toward improvement |
| Patients with distant metastasis or locoregional recurrence | Postrecurrence progression-free survival | 0.691 (0.497-0.961) | Improved with SCRT-TNT |
| Patients with distant metastasis or locoregional recurrence | Postrecurrence survival | 0.698 (0.490-0.994) | Improved with SCRT-TNT |
Safety Profile
The available abstract for this 5-year update does not report adverse event or toxicity rates by treatment arm. Acute toxicity and surgical complications were collected as secondary outcomes in the original trial design, but arm-level figures from this updated analysis were not available in the sources consulted for this article. Quality of life and anorectal function outcomes were reported as comparable between arms in outside press coverage of the trial, though specific figures were not given.
These results suggest that SCRT-based TNT provides a durable survival advantage and is a viable alternative to CRT, especially in patients with high-risk disease.
— Study authors, PubMed abstract (PMID 42507974)
Interpretation and Broader Context
These 5-year results add mature follow-up to a trial that has already begun influencing discussion of TNT sequencing for locally advanced rectal cancer. The clearest signal is in high-risk patients by ESMO criteria, where both the overall survival benefit and a directional disease-free survival trend favored SCRT-TNT. Among patients who went on to develop distant metastasis or locoregional recurrence, prior treatment with SCRT-TNT was also linked to better postrecurrence progression-free survival (HR 0.691) and postrecurrence survival (HR 0.698).
Independent press coverage characterized the survival difference as roughly an 8.4% absolute survival advantage for the short-course approach, consistent with the 78.1% vs 69.7% figures in the abstract, and reported comparable quality-of-life and anorectal function outcomes between arms. That coverage indicated investigators are exploring whether adding immunotherapy to the SCRT-TNT backbone could further improve outcomes, and are working to better define which patients benefit most. Because full trial-report methodology and complete safety data were not available in a public full-text version at the time of this article, readers seeking treatment-planning detail — arm-level toxicity, exact analyzed sample sizes, statistical methods for the subgroup analyses — should consult the full published article in the Journal of Clinical Oncology once available.
At a median follow-up of 68.7 months, the STELLAR trial's short-course radiotherapy-based total neoadjuvant therapy regimen produced a statistically significant 5-year overall survival advantage over standard long-course chemoradiotherapy (78.1% vs 69.7%, HR 0.739) in locally advanced rectal cancer, though disease-free survival was not significantly different between arms (62.0% vs 58.7%). The benefit was most pronounced in high-risk patients by ESMO criteria. Safety data from this update were not available in the source abstract, and full trial-report detail should be reviewed once the complete article is published.