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Anal Cancer Treatment

In recent years, there have been improvements in the treatment of anal cancer. Patients with knowledge about recent research on anal cancer can better advocate for themselves and get the best care.

Key Takeaways

  • Radiation: Image-guided radiation therapy with daily cone beam CT is recommended for more precise treatment, reducing toxicity and improving side effects. 
  • Vaginal Dilators: Using dilators during or after radiation may lower the risk of long-term vaginal stenosis.
  • Tumor Size: For tumors under 4 cm, lower chemoradiation doses may be equally effective; ongoing trials are investigating this.
  • Chemotherapy: A single dose of Mitomycin causes less toxicity than two doses. Oral capecitabine is less toxic than infusional 5-FU.
  • Recurrence Risk: Increases with inconsistent treatment (e.g., dose reductions, delays over 42 days), tumors ≥5 cm, or lymph node involvement.
  • Immunotherapy: Ongoing trials show promise, but more research is needed.
  • Screening: The Anchor Study confirms screening and treating precancerous cells reduces anal cancer rates, but limited trained professionals hinder widespread adoption.

See our explanation of the Anchor Study here.

Surveillance after Treatment

  • The surgeon plays a key role in assessing treatment success or disease regression
  • Follow-up is recommended 8-12 weeks after treatment, with biopsies considered for lesions showing growth at 3 months
  • Stable or regressing disease at 3 months doesn’t mean lack of response and should be monitored monthly, with up to 6 months allowed to achieve full clinical response. 
  • Full Explanation of “Anal Cancer: Emerging Standards in a Rare Cancer Disease” → The published article can be found here.

Anal Cancer Treatments: Interviews with Professionals

Cathy Eng, MD, FACP, FASCO 

  • Professor of Medicine in the Division of Hematology and Oncology, Department of Medicine Co-director of GI Oncology
  • Co-leader of the Gastrointestinal Cancer Research Program at Vanderbilt University Medical Center
  • Dr. Eng manages clinical trials for new drugs to treat anal cancer. Dr. Eng has had leadership roles in ASCO, ASCO GI, ECOG, SWOG, and the National Cancer Institute (NCI). She recently published a review of recent trends in anal cancer and its treatment in the Journal of Clinical Oncology here. We wrote a summary of her article here.

Dr. Eng’s takeaways include:

  • Do not interrupt chemoradiation treatment to take a break. Interrupting treatment for over one or two days increases the risk of incomplete response or local recurrence.
  • Gain a second opinion. It is a rare cancer so too frequently anal cancer patients receive inadequate medical care.
  • Oral Chemotherapy (Capacitabene/Xeloda) is equivalent in terms of successful response to treatments (not recommended for patients prone to nausea or motion sickness)
  • Anal cancer is a multi-disciplinary disease treated by a team of oncologists who need to agree on the best treatments.
  • Annual PAP tests with a co-test for HPV are necessary. Women who have had anal cancer are at risk for getting an adjacent HPV-associated cancer. 

Listen to our Interview with Dr Cathy Eng Here

Dr. Paul Romesser: Radiation Oncology Specialist
: Dr. Paul Romesser, a board-certified radiation oncologist at Memorial Sloan Kettering Cancer Center, specializes in advanced cancer treatments like IMRT, VMAT, and stereotactic radiosurgery. Actively involved in anal cancer clinical trials, he serves on NRG Oncology and NCI committees, with research published in top journals like Nature and Cancer.

Radiation for Anal Cancer

The standard for anal cancer treatment is IMRT, which reduces gastrointestinal and urinary side effects compared to older methods like 3D CRT. VMAT, a more advanced version of IMRT, combined with image-guided radiation ensures precise daily targeting, minimizing setup variations. Although proton therapy is heavily marketed, it lacks evidence of clinical benefits for anal cancer.

Advice for Patients

Patients should prioritize IMRT or VMAT with image guidance and ask their doctor about treatment machines, outcomes, side effects, and post-treatment support like pelvic floor therapy and sexual health programs.

Disparities in Side Effects

Side effects vary due to factors like cancer stage, lymph node involvement, and individual sensitivity to radiation. Oncologists monitor patients closely to address any concerns during treatment.

Radiation Oncology Experience

Radiation oncologists design individualized treatment plans for each patient. After a radiation mapping or simulation scan, the oncologist, with a team of medical physicists, optimizes the plan and seeks peer review. Treatment plans vary slightly among oncologists due to acceptable variations, but expertise and board certification ensure high-quality care. Patients should confirm their oncologist is board-certified and experienced in treating their specific cancer type.

Oral vs. Port Chemo

Oral chemotherapy (Capecitabine/Xeloda) is a prodrug of 5-FU, offering an alternative to port-administered 5-FU. Both are considered equally effective but differ in side effects. Oral chemo is preferred for most anal cancer patients unless medical conditions prevent its use. Patients should ask their oncologist why one method is preferred at their treatment center.

Radiation Treatment Duration

Treatment typically lasts 23–30 sessions, depending on the stage. Variations across centers are normal and acceptable.

Full Bladder During Radiation

A full bladder reduces radiation exposure to the small intestine, potentially preventing side effects like bleeding or strictures. Not all patients require this approach. Oncologists tailor the decision based on each patient’s anatomy, and patients should ask if a full bladder is necessary for their treatment.

Vaginal Dilators During Radiation

Vaginal dilators may reduce radiation exposure to sensitive areas of female anatomy, potentially minimizing long-term side effects. While no large studies confirm their benefits, some centers, like Memorial Sloan Kettering, routinely use them. Patients should ask their radiation oncologist if dilators are part of their protocol and why.