International Watch and Wait Database (IWWD)

Background

International Watch and Wait Database (IWWD). Prospective registry, N=880, rectal cancer with clinical complete response (cCR) after preoperative (chemo)radiotherapy managed non-operatively (watch-and-wait); 47 institutions, 15 countries. Largest prospective W&W evidence base.

Interventions and follow up

Treatment: Non-operative watch-and-wait after cCR to neoadjuvant (chemo)radiotherapy
Primary endpoint: Local regrowth; distant metastases, organ preservation, OS
mFollow up: Median 3.3 yr

Results

2-yr local regrowth: 25.2%
Salvage surgery (among regrowths): 88% salvageable with radical surgery
R0 resection of regrowths: 95%
5-yr OS: 84.9%
3-yr disease-specific survival: 86.9%

Adverse events

Organ preservation: ~75% at 2 yr
Salvage outcomes: R0 resection 95% among regrowths requiring surgery
Distant disease: No significant difference between salvaged regrowth vs no-regrowth cases

Conclusions

In rectal cancer with cCR after preoperative CRT, watch-and-wait achieves organ preservation in ~75% at 2 yr and 5-yr OS ~85%. Local regrowth (25.2%, most within 2 yr) is salvageable with radical surgery in 88%. Safe, effective organ-preserving strategy in carefully selected cCR patients.

Key Limitations

Observational registry, no surgical comparator arm; cCR definition and surveillance protocols varied across centers; selection bias; relatively short median follow-up for a curative-intent setting.

Clinical Context

Foundational prospective evidence for organ preservation in rectal cancer; supports W&W as an option for cCR after total neoadjuvant therapy with close structured surveillance, consistent with ASCO/ESMO endorsement of nonoperative management in selected patients.

References