Watch-and-Wait Success in High-Risk Rectal Cancer: ESMO GI 2026 Findings

Long-term data presented at the ESMO GI 2026 Congress provide new reassurance for the use of a “watch-and-wait” (W&W) strategy in patients with rectal cancer who achieve a clinical complete response (cCR) following chemoradiotherapy (CRT).

The real-world study, which followed patients for a median of 8.0 years, demonstrated that while local regrowth is common, it remains highly salvageable through surgery, and overall rectal cancer-specific survival remains high.

The study, led by researchers at The Royal Marsden NHS Foundation Trust, focused on 165 patients with localized rectal adenocarcinoma treated between 2005 and 2020. All participants had achieved a cCR —defined by MRI tumor regression grades (mrTRG) 1 or 2 — and subsequently moved into a W&W surveillance program rather than undergoing immediate radical surgery.

Understanding the "safety net" of salvage surgery

For oncology nurses and clinicians, the primary concern with organ-preservation strategies is the risk of local regrowth and whether such occurrences can be managed curatively. This study found that 43.6% of the cohort developed local regrowth during the follow-up period. The timing of these regrowths was concentrated in the early years of surveillance; 94.4% of regrowths occurred within the first 2 years after completing CRT, and 97.2% occurred within 3 years.

Despite the relatively high regrowth rate, the "safety net" of surgical salvage proved robust. Investigators reported that 94.4% of local regrowths were surgically salvageable. Among those who underwent salvage surgery (Total Mesorectal Excision or TME), an R0 resection rate of 89.8% was achieved, indicating no cancer cells were left at the resection margins. Furthermore, 18.3% of patients undergoing salvage surgery were still able to receive sphincter-preserving procedures, avoiding a permanent stoma.

The predictive power of MRI biomarkers

A critical component of the research involved comparing outcomes based on the quality of the initial response to CRT, as measured by MRI. Patients were categorized into two groups: Best mrTRG1 (representing no or minimal fibrosis) and Persistent mrTRG2 (representing dense fibrosis).

The results highlighted a significant disparity in long-term outcomes between these groups. The 5-year rate was 64.1% for those with mrTRG1 compared to 44.0% for those with persistent mrTRG2.

Rectal cancer-specific survival

The 5-year survival rate was 98.8% for mrTRG1 patients, whereas it was 82.6% for the mrTRG2 group.

By the 8-year mark, the rectal cancer-specific survival for the persistent mrTRG2 group dropped further to 63.3%, while the mrTRG1 group remained high at 94.2%. This suggests that patients with a persistent mrTRG2 response require particularly vigilant monitoring and perhaps a lower threshold for surgical intervention.

Overcoming adverse baseline features

One of the most striking aspects of this study was the high-risk nature of the patient population. At baseline, 73.9% of patients had T3/T4 disease, 64.2% were node-positive, and 71.5% had a threatened circumferential resection margin (CRM). Additionally, over half (52.4%) exhibited extramural vascular invasion (EMVI).

The fact that favorable long-term oncological outcomes were achieved in such a high-risk group suggests that a W&W approach is not only for "low-risk" patients but can be successfully applied to more advanced cases, provided they achieve a deep clinical response to initial therapy.

Clinical implications for oncology nursing

The role of the oncology nurse is pivotal in the successful execution of a W&W program. These findings underscore the importance of intensive surveillance during the first 24 to 36 months, as this is when nearly all regrowths occur. Nurses play a key role in educating patients about the necessity of frequent follow-up appointments and imaging to ensure that any regrowth is caught while it is still surgically salvageable.

Furthermore, the data regarding distant metastasis provide a sobering reminder of the systemic risks. The study found that the incidence of distant metastases was significantly higher in patients who experienced local regrowth compared to those who did not (34.7% vs 4.3%; p<0.001). The most common sites for these metastases were the lungs (42.5%) and liver (35.0%). This highlights the need for comprehensive systemic monitoring alongside local rectal surveillance.

In conclusion, while a persistent mrTRG2 response is associated with inferior survival and a higher risk of regrowth, the overall W&W strategy remains a highly effective option for rectal cancer patients, offering a significant chance of organ preservation without compromising long-term curative potential.

Reference

Katifi HN, Brown G, Shur J, et al. Long-term oncological outcomes of a watch-and-wait approach following chemoradiotherapy in rectal cancer: A real-world series. Poster presented at: ESMO Gastrointestinal Cancers Congress 2026; June 2026; Munich, Germany. Poster 310P.