In patients with chronic CD and a long-standing perianal fistula showing recent rapid growth, is anti-TNF therapy alone or adding local radiation before surgery preferred

What is known

- Long-standing symptomatic fistulizing perianal crohn's can progress beyond inflammation to malignancy; anal SCC is treated with chemoradiation, so pathology must be secured before treatment. ¹ - Anal/perianal cancers complicating long-standing crohn's are managed with combined radiation and chemotherapy first-line, with surgery reserved for persistent or recurrent disease. ^1,2 - In the PISA-II RCT, short-term anti-TNF combined with surgical closure gave higher radiological healing than anti-TNF alone, with fewer re-interventions. ^3,4 - Anti-TNF is the most effective medical therapy for complex perianal fistulas but only a minority achieve durable healing; multidisciplinary combined medical-surgical management is standard. ^5–8

What is unknown / caveats

- No retrieved study evaluates local radiation as an adjunct to anti-TNF for benign crohn's fistula — radiation appears only in an oncologic context - PISA-II required a surgically amenable high fistula with a single internal opening, which may not apply to a rapidly changing tract - The corpus does not support radiation for a benign crohn's fistula, so the direct anti-TNF-alone versus anti-TNF-plus-radiation comparison you pose cannot be answered as framed.

## References

1. Ganapathy A, Navale P, Mutch MG, Kim H, Ballard DH, Deepak P. Long-Standing Symptomatic Fistulizing Perianal Crohn's Disease: Progression Beyond Inflammation. Gastroenterology. 2024;166(1):36-43.e2. PMID: 37709172.

2. Lightner AL, Moncrief SB, Smyrk TC, Pemberton JH, Haddock MG, Larson DW, Dozois EJ, Mathis KL. Long-standing Crohn's disease and its implication on anal squamous cell cancer management. Int J Colorectal Dis. 2017;32(5):661-666. PMID: 28293746.

3. Meima-van Praag EM, Becker MAJ, van Rijn KL, Wasmann KATGM, Stoker J, D'Haens GRAM, Ponsioen CY, Gecse KB, Dijkgraaf MGW, Spinelli A, Danese S, Bemelman WA, Buskens CJ. Short-term anti-TNF therapy with surgical closure versus anti-TNF therapy alone for Crohn's perianal fistulas (PISA-II): long-term outcomes of an international, multicentre patient preference, randomised controlled trial. EClinicalMedicine. 2023;61:102045. PMID: 37457118.

4. Meima-van Praag EM, van Rijn KL, Wasmann KATGM, Snijder HJ, Stoker J, D'Haens GR, Gecse KB, Gerhards MF, Jansen JM, Dijkgraaf MGW, van der Bilt JDW, Mundt MW, Spinelli A, Danese S, Bemelman WA, Buskens CJ. Short-term anti-TNF therapy with surgical closure versus anti-TNF therapy in the treatment of perianal fistulas in Crohn's disease (PISA-II): a patient preference randomised trial. Lancet Gastroenterol Hepatol. 2022;7(7):617-626. PMID: 35427495.

5. Bourikas LA, Koutroubakis IE. Anti-TNF and fistulizing perianal Crohn's disease: use in clinical practice. Curr Drug Targets. 2010;11(2):187-97. PMID: 19916954.

6. Chan M, Fung M, Chin Koon Siw K, Khanna R, de Buck van Overstraeten A, Sabri E, McCurdy JD. Examination Under Anesthesia May Not Be Universally Required Prior to Anti-TNF Therapy in Perianal Crohn's Disease: A Comparative Cohort Study. Inflamm Bowel Dis. 2023;29(5):763-770. PMID: 35815783.

7. Tozer P, Borowski DW, Gupta A, Yassin N, Phillips R, Hart A. Managing perianal Crohn's fistula in the anti-TNFα era. Tech Coloproctol. 2015;19(11):673-8. PMID: 26264168.

8. Vasudevan A, Bruining DH, Loftus EV, Faubion W, Ehman EC, Raffals L. Approach to medical therapy in perianal Crohn's disease. World J Gastroenterol. 2021;27(25):3693-3704. PMID: 34321838.

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_Draft — generated by the IBDology RAG and not yet clinician-reviewed. Answers are grounded in the retrieved literature listed above; a high faithfulness score means the answer matches its sources, not that the sources are correct._