What happened, in summary

A woman in her 40s had lived with mainly colonic Crohn disease since her late teens. Her history included anal narrowing, perianal abscesses, and a previous rectovaginal fistula. After 2 months of fatigue, abdominal pain, poor appetite, and mucus in the stool, colonoscopy found an ulcerated lesion in a deformed anal canal. Biopsies showed rectal adenocarcinoma.

She received neoadjuvant chemoradiotherapy. At 7 weeks, examination and imaging suggested a near-complete response, but chronic inflammation from Crohn disease made it difficult to be certain that no tumor remained. Further assessments at 12 and 24 weeks continued to show tumor regression.

Because reliable surveillance was challenging, major rectal surgery was recommended. She declined surgery and chose a carefully informed watch-and-wait strategy to avoid a permanent ostomy and the risks of operating in an inflamed pelvis.

For the first 2 years, follow-up included digital examination, proctoscopy, and diffusion-weighted MRI every 3 months. Surveillance then continued every 6 months through year 5, together with CEA testing, CT scans, and annual colonoscopy.

No local regrowth or distant disease was found during surveillance. At the latest follow-up, she had remained disease-free for 9 years after chemoradiotherapy without rectal surgery. Her outcome depended on very close, long-term monitoring and her willingness to return promptly for repeated examinations.

Crohn-related scarring made examinations harder to interpret throughout follow-up. Avoiding surgery required accepting frequent procedures and the possibility of immediate surgery if regrowth appeared. No local or distant recurrence appeared over 9 years.