Procedure

Chemoradiation

Back to work: 4-8 weeks (acute side effects)
Success rate: 80-90% (local control for anal cancer)
Recurrence: 10-30% (for anal cancer)

What it is

What is Chemoradiation?

Chemoradiation is the concurrent use of chemotherapy and radiation therapy. For anal and rectal cancers, this combination is used to improve the effectiveness of radiation by making cancer cells more susceptible to its effects. This approach can shrink tumors, making them easier to remove surgically, or in some cases, eradicate the tumor entirely, allowing for organ preservation.

For Anal Cancer

For most stages of anal squamous cell carcinoma, definitive chemoradiation is the standard of care, with surgery reserved for salvage. The most common regimen is the Nigro protocol, which combines external beam radiation with 5-fluorouracil (5-FU) and mitomycin C.

For Rectal Cancer

For locally advanced rectal cancer (stage II and III), neoadjuvant chemoradiation is used to downstage the tumor, reduce the risk of local recurrence, and increase the likelihood of sphincter preservation. The standard regimen involves external beam radiation with concurrent 5-FU or capecitabine.

Am I a candidate?

Who are Good Candidates for Chemoradiation?

Anal Cancer: Patients with squamous cell carcinoma of the anal canal of almost any stage are candidates for definitive chemoradiation.
Rectal Cancer: Patients with locally advanced rectal cancer (clinical stage II or III) are candidates for neoadjuvant chemoradiation to improve local control and downstage the tumor prior to surgery. It is also used as a component of total neoadjuvant therapy (TNT).

Patient selection depends on tumor stage, location, overall health, and goals of care.

Recovery

What is the Recovery Like?

Recovery from the acute side effects of chemoradiation typically takes several weeks to months. Skin reactions usually heal within a month of completing treatment. Bowel and bladder function may take longer to return to baseline. Long-term effects can be permanent and may require ongoing management. For rectal cancer patients undergoing surgery after neoadjuvant treatment, there is typically a waiting period of 8-12 weeks to allow for maximal tumor response and for acute radiation side effects to subside.

Risks & considerations

What are the Risks?

Chemoradiation has both acute and long-term risks and side effects. Acute side effects during treatment can include fatigue, nausea, diarrhea, painful skin reactions (radiation dermatitis) in the perineum, and bone marrow suppression. Long-term risks can include chronic diarrhea, fecal incontinence, bladder and sexual dysfunction, pelvic fractures, and an increased risk of secondary malignancies. For rectal cancer patients, neoadjuvant chemoradiation is generally better tolerated and has fewer long-term side effects than when it is given postoperatively.

Sources

Steele SR, Hull TL, Hyman N, Maykel JA, Read TE, Whitlow CB, eds. The ASCRS Textbook of Colon and Rectal Surgery. 4th ed. Springer; 2022.
National Comprehensive Cancer Network. (2020). Anal Carcinoma (Version 2.2020). https://www.nccn.org/professionals/physician_gls/pdf/anal.pdf. Accessed October 15, 2025.
National Comprehensive Cancer Network. (2020). Rectal Cancer (Version 4.2020). https://www.nccn.org/professionals/physician_gls/pdf/rectal.pdf. Accessed October 15, 2025.