Frequently Asked Questions

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Which treatment will I get?

You and your doctor will decide together which treatment to use based on

  • Size of HSIL
  • Location of HSIL
  • Your preferences or ability to tolerate the treatment

What are the treatments for HSIL?

Treatment of HSIL usually requires more than one visit.  HSIL often comes back in the same or new location. If one approach to treatment is not working, another treatment may be tried.

There are three approaches to treatment in the ANCHOR study.


Using an anoscope and a camera to see inside the anal canal, vinegar is swabbed on the skin to make the HSIL show up as white.  The area to be treated is numbed with a numbing jelly followed by an injection of lidocaine. Heat is applied to the HSIL for a split second to the lesion using either
  • a machine called an "infra-red coagulator" (IRC) which uses a quartz wand to apply heat to the lesion or
  • "Electrocautery" which uses a thin loop of wire as an electric scalpel to burn off the lesion


You will apply Imiquimod or 5-fluorouracil cream to your anus at bedtime every night for several weeks using your gloved finger.


Surgery is rarely used except in cases where the HSIL is spread over a large area or will not respond to the other treatments.

What are the side effects of treatment?

Pain at site of biopsy and heat treatment. Bleeding may last up to a week but is a normal part of the healing process. Pain may be worst when going to bathroom. Drinking lots of water, stool softeners, sitz baths and tylenol can all help with pain when going to the bathroom. When using the Imiquimod and 5-FU creams, you will get a rash as these creams act like a chemical peel of the anal skin. You may need to take a day off work. Surgery may require several days off work as you recover from the effects of the anesthesia and the surgery. You will need to take a few weeks off from anal sex.

Why compare treatment to monitoring?

We don't know if treating HSIL actually prevents anal cancer. The ANCHOR study is designed to answer this question by comparing treatment of HSIL against active monitoring of HSIL with no treatment. Unlike many trials that compare the effectiveness of two or more treatments, the ANCHOR Study is simply comparing treatment vs. no treatment. This means that if you are randomized to the treatment arm, you may get one or a combination of treatments for HSIL, similar to what you would receive outside the study.

What are the advantages of being in the Active Monitoring Arm?

Treating anal HSIL may not be better than active monitoring to reduce the risk of anal cancer. If so, you would have avoided uncomfortable treatments that provide little benefit to you.

What are the disadvantages of being in the Active Monitoring Arm?

You may be anxious knowing that you have anal HSIL that is being closely monitored but not being treated. The study may show that the risk of progressing to cancer is higher if you are being watched instead of being treated.

What are the advantages of being in the Treatment Arm?

The study may show that the risk of progressing to cancer is lower if you are being treated instead of being watched.

What are the disadvantages of being in the Treatment Arm?

Each of the treatments has discomfort and side effects associated with them. You may need more than one kind of treatment over the course of the study, and even then it is possible that the doctors may not be able to remove all of the HSIL. If the study shows that those treatments were not helpful in reducing the risk of progressing to cancer, you may have had discomfort and side effects due to treatment that did not help you.

What are the advantages of being in either arm of the study?

If you do develop cancer during the study, there is a chance that the cancer may be caught earlier than if you were not in the study and not being followed at all. Cancers caught earlier tend to respond better to treatment, and may possibly be treated with a simple local removal in the operating room instead of chemotherapy and radiation therapy.