Anal cancer

What is anal cancer?

Anal cancer is a disorder in which the tissues of the anus develop malignant (cancer) cells. The anus is the end of the large intestine, below the rectum, from which the body leaves stool (solid waste). The anus is formed partly from the body’s outer skin layers and partly from the gut. Two ring-like muscles open and close the anal opening, called sphincter muscles, and let the stool migrate out of the body. Approximately 1-11⁄2 inches long is the anal canal, the part of the anus between the rectum and the anal opening.

The skin is called the perianal area around the outside of the anus. Perianal skin tumors that do not affect the anal sphincter are typically treated in the same manner as anal cancers, although some can undergo local therapy (treatment directed at a small area of the skin).

Most anal cancers are related to human papillomavirus (HPV) infection.

Risk factors for anal cancer

Risk factors for anal cancer include the following:

• Being infected with human papillomavirus (HPV).
• Having a condition or disease that causes a weakened immune system, such as human immunodeficiency virus (HIV) or an organ transplant.
• Having a personal history of vulvar, vaginal, or cervical cancers.
• Having many sexual partners.
• Having receptive anal intercourse (anal sex).
• Smoking cigarettes.

Signs of anal cancer include bleeding from the anus or rectum or a lump near the anus.

Anal cancer or other disorders may be responsible for these and other signs and symptoms. If you have any of the following things, consult with your doctor:

• Bleeding from the anus or rectum.
• A lump near the anus.
• Pain or pressure in the area around the anus.
• Itching or discharge from the anus.
• A change in bowel habits.

Tests that examine the rectum and anus are used to diagnose anal cancer.

The following tests and procedures may be used:

• Physical exam and health history: A body inspection to check general health symptoms, including looking for signs of sickness, such as lumps or something else that appears odd. There will also be a summary of the patient’s personal patterns and previous conditions and treatments.
• Digital rectal examination (DRE): Analysis of the rectum and anus. A lubricated, gloved finger is inserted into the lower portion of the rectum by the doctor or nurse to feel for lumps or something else that appears odd.

• Anoscopy: An examination of the anus and lower rectum using an anoscope called a small, illuminated tube.
• Proctoscopy: A test with a proctoscope to look into the rectum and anus to search for suspicious areas. For viewing the inside of the rectum and anus, a proctoscope is a small, tube-like device with a light and a lens. It may also include a tool for the removal of tissue samples that are examined for cancer signs under a microscope.
• Endo-anal or endorectal ultrasound: A technique in which an ultrasound transducer (sample) is inserted into the anus or rectum and used to bounce and make echoes of high-energy sound waves (ultrasound) off internal tissues or organs. The echoes form an image called a sonogram of body tissues.
• Biopsy: The removal of cells or tissues so that a pathologist can examine them under a microscope to search for signs of cancer. A biopsy can be performed at that time if a suspicious area is seen during the anoscopy.

Certain factors affect the prognosis (chance of recovery) and treatment options.

The prognosis depends on the following:

• The size of the tumor.
• Whether the cancer has spread to the lymph nodes.

The treatment options depend on the following:

• The stage of the cancer.
• Where the tumor is in the anus.
• Whether the patient has human immunodeficiency virus (HIV).
• Whether cancer remains after initial treatment or has recurred.

Stages of Anal Cancer

KEY POINTS

• After anal cancer has been diagnosed, tests are done to find out if cancer cells have spread within the anus or to other parts of the body.
• There are three ways that cancer spreads in the body.
• Cancer may spread from where it began to other parts of the body.
• The following stages are used for anal cancer:
  • Stage 0
  • Stage I
  • Stage II
  • Stage III
  • Stage IV
• Anal cancer can recur (come back) after it has been treated.

The procedure used to find out whether cancer has spread inside the anus or to other body parts is called staging. The stage of the illness is determined by the data obtained from this staging process. In order to schedule treatment, it is necessary to know the point. In the staging process, the following tests can be used:

• CT scan (CAT scan): A technique that takes a series of detailed photographs, taken from various angles, of areas within the body, such as the abdomen, pelvis, or chest. A computer connected to an x-ray machine generates the images. To make the organs or tissues show up more clearly, a dye can be injected into a vein or swallowed. Computed tomography, computerized tomography, or computerized axial tomography are also called this technique.
• Chest x-ray: An x-ray of the bones and organs inside the chest. An x-ray is a type of energy beam that can go through and onto film through the body, creating an image of areas within the body.
• MRI (magnetic resonance imaging): A technique for making a series of informative pictures of areas within the body using a magnet, radio waves, and a monitor. Often known as nuclear magnetic resonance imaging, this approach is (NMRI).
• PET scan (positron emission tomography scan): A technique for identifying the body’s malignant tumor cells. A small amount is pumped into a vein with radioactive glucose (sugar). The PET scanner rotates around the body and creates an image of where the body uses glucose. In the picture, malignant tumor cells appear brighter as they are more active and take up more glucose than normal cells do.
• Pelvic exam: Vagina, cervix, uterus, fallopian tubes, ovaries, and rectum tests. A speculum is inserted into the vagina and the vagina and cervix are checked at by the doctor or nurse for signs of illness. A cervix pap examination is normally performed. In order to feel the scale, shape, and location of the uterus and ovaries, the doctor or nurse often inserts one or two lubricated, gloved fingers of one hand into the vagina and positions the other hand over the lower abdomen. A lubricated, gloved finger is often inserted into the rectum by the doctor or nurse to feel for lumps or irregular regions.

What are the treatment options in anal cancer ?

Three types of standard treatment are used:

Anal cancer Surgery

• Local resection: A surgical technique in which, along with some of the healthy tissue surrounding it the tumor is cut from the anus. If the cancer is small and has not propagated, local resection may be used. This procedure can save the muscles of the sphincter so that bowel movements can still be controlled by the patient. With local resection, tumors that develop in the lower part of the anus may also be removed.
• Abdominoperineal resection: A surgical procedure that removes the anus, rectum, and part of the sigmoid colon through an incision created in the abdomen. In order to collect body waste in a disposable bag outside the body, the doctor sews the end of the intestine to an opening called a stoma made on the surface of the abdomen. A colostomy is called this. During this procedure, lymph nodes that contain cancer can also be removed. This technique is only used for cancer that persists or comes back after radiation therapy and chemotherapy treatment.

Surgery for Anal Cancer

Surgery isn’t the first procedure used for anal cancer in most cases. The method of procedure depends on the type and location of the tumor for patients who do need surgery.

Local resection

Local resection is a procedure in which only the tumor is removed, plus a thin margin (edge) of normal tissue around the tumor. If the tumor is small and has not spread to surrounding tissues or lymph nodes, it is most commonly used to treat cancers of the anal margin.

Local resection most frequently saves the muscles of the sphincter that prevent the stool from falling out until they relax after a bowel movement. This helps a person after the surgery to naturally move their bowels.

Abdominoperineal resection

A big procedure is an abdominoperineal (or APR) resection. In the abdomen (belly), the surgeon makes one incision (cut) and another around the anus to extract the anus and the rectum. Any of the surrounding groin lymph nodes can also be cut out by the surgeon, but this (called a dissection of the lymph node) can also be done later.

The anus (and the anal sphincter) are gone, so it is important to make a new opening for the stool to leave the body. The end of the colon is connected to a tiny hole (called a stoma) created in the abdomen to do this. Over the opening, a bag to collect stool adheres to the body. A colostomy is called this.

APR was a common treatment for anal cancer in the past, but physicians have found that by using radiation therapy and chemotherapy now it can almost always be prevented. APR is used today only if other therapies do not work or if the cancer returns after treatment.

Possible risks and side effects of surgery

Potential side effects of surgery, including the nature of the surgery and the health of the person before surgery, depend on many factors. After the procedure, most people may feel at least some discomfort, but it can typically be managed with medication. Other issues may include anesthesia reactions, damage to nearby organs, swelling, leg blood clots, and infection.

APR appears to have more side effects, many of which are improvements that are long-lasting. You could grow scar tissue (called adhesions) in your abdomen after an APR, for example, which may cause organs or tissues to bind together. This might cause food passing through the intestines to have discomfort or complications, which can lead to digestive problems.

After an APR, people still require a permanent colostomy. This will take some time to get used to some lifestyle changes and might mean them.

An APR may cause erection problems for males, trouble getting an orgasm, or the orgasm satisfaction can become less intense. An APR may also damage the nerves that regulate ejaculation, resulting in “dry” orgasms (orgasms without semen).

Typically, APR does not cause women to lose sexual function, but abdominal (scar tissue) adhesions can often cause pain during intercourse.

Anal cancer radiation therapy

Radiation therapy is a cancer treatment that destroys cancer cells or prevents them from developing using high-energy x-rays or other forms of radiation. Two kinds of radiation therapy are available:

• To deliver radiation to the region of the body with cancer, external radiation therapy uses a machine outside the body.
• A radioactive material sealed in needles, seeds, cables, or catheters which are inserted directly into or near the cancer is used in internal radiation therapy.

The way the radiation therapy is given depends on the type and stage of the cancer being treated. External and internal radiation therapy are used to treat anal cancer.

The most common way for anal cancer to be treated with radiation is by using a focused beam of radiation that comes from a machine outside the body. This is known as external-beam radiation therapy.

Radiation can harm nearby healthy tissues along with the cancer cells. This causes side effects. To reduce the risk of side effects, doctors carefully figure out the exact dose you need and aim the beams as accurately as they can. Before treatment starts, the radiation team will get PET/CT or MRI scans of the area to be treated to help figure this out. Radiation therapy is much like getting an x-ray, but the radiation is stronger. The procedure itself doesn’t hurt. Each treatment lasts only a few minutes, but the setup time – getting you into place for treatment – usually takes longer. For a span of 5 weeks or so, treatments are typically offered 5 days a week.

New techniques allow physicians to provide cancer with higher doses of radiation while reducing radiation to healthy tissues nearby:

3D-CRT (three-dimensional conformal radiation therapy) uses special computers to reliably chart the cancer site. Radiation beams are then formed from many directions and directed at the tumor. This makes them less likely to have normal tissues affected. In order to hold you in the very same place each time, you will most likely be fitted with a plastic mold like a body cast so that the radiation can be directed more precisely.

An advanced form of 3-D therapy and the recommended method of EBRT for anal cancer is intensity modulated radiation therapy (IMRT). It uses a computer-driven system that as it delivers radiation, actually travels around you. The intensity (strength) of the beams can be changed along with forming the beams and aiming them from several angles. It helps to limit the dose that enters normal tissues. IMRT helps doctors to administer an even higher cancer dose.

Side effects of external radiation therapy

The side effects differ depending on the part of the body treated and the radiation dose given. Some common side effects of short-term use include:

• Diarrhea
• Skin changes (like a sunburn) in areas being treated
• Short-term anal irritation and pain (called radiation proctitis)
• Discomfort during bowel movements
• Tiredness
• Nausea
• Low blood cell counts

Radiation might irritate the vagina in women. This can contribute to discomfort and release.

After radiation ceases, most of these side effects get stronger over time.

Also, long-term side effects can occur:

• Radiation damage to the anal tissue can cause scar tissue to form. This can also prevent the muscle of the anal sphincter from acting as it should, which may contribute to bowel movement issues.
• Pelvic radiation can damage bones, raising the risk of pelvic or hip fractures.
• Radiation can damage the blood vessels that nourish the rectum lining and cause chronic radiation proctitis (inflammation of the lining of the rectum). Rectal bleeding and discomfort may be caused by this.
• Radiation can affect fertility (the ability to have children) in both women and men. (For more on this, see Fertility and Men With Cancer and Fertility and Women With Cancer.)
• Radiation may lead to dryness of the vagina and even vaginal narrowing or shortening (called vaginal stenosis), which can make sex painful. By stretching the walls of her vagina many times a week a woman can help avoid this problem. It is possible to do this using a vaginal dilator (a plastic or rubber tube used to stretch out the vagina).
• It can lead to swelling problems in the genitals and legs, called lymphedema, if radiation is provided to lymph nodes in the groin.

Internal radiation (brachytherapy)

In order to treat anal cancer, internal radiation is not widely used. When used, when a tumor does not respond to normal chemoradiation, it is normally provided as a radiation boost along with external radiation (chemo plus external radiation).

Internal radiation requires the placing in or near the tumor of small sources of radioactive materials. It can also be called intracavitary radiation, interstitial radiation, or brachytherapy. It is used to concentrate on the radiation in the cancer region.

The side effects that are possible are a lot like those seen from external radiation.

Intensity-Modulated Anal Cancer Radiation Therapy

The most common form of radiation for anal cancer is intensity-modulated radiation therapy (IMRT). It is a form of radiation from the outside-beam. IMRT uses a technologically sophisticated computer software such that the radiation beams can be correctly molded to the dimensions of the region of treatment by your care team.

Expert radiation oncologists and medical physicists will gather accurate information about the treatment area before treatment starts. You’ll have:

• a CT scan to map the tumor in 3-D
• PET, CT, and MRI scans to identify the outline of the tumor

This knowledge is used by your care team along with advanced treatment-planning tools. We can measure the correct number of radiation beams and the exact angle of those beams with this application. Before the radiation treatment, you can also undergo chemotherapy to weaken the cancer cells. This causes the radiation to be more effective.

This method helps us to provide the tumor with more specific doses of radiation while preserving the healthy tissue in the vicinity.

Proton therapy for anal cancer

A type of radiation that uses charged particles called protons is proton therapy. X-rays are used by standard radiation. The risk of damage to healthy tissue may be reduced by proton therapy because proton beams do not reach past the tumor. It also helps us to provide higher radiation doses, maximizing the risk of tumor destruction.

A relatively recent approach is to use proton therapy to treat anal cancer. Its advantages are still being investigated by physicians. For the treatment of head and neck cancer and childhood cancers, proton therapy is most widely used.

Anal cancer chemotherapy

Chemotherapy is a type of treatment for cancer that uses medicines to stop cancer cell development, either by destroying the cells or by preventing the cells from dividing. The medications enter the bloodstream if chemotherapy is taken by mouth or inserted into a vein or muscle and may reach cancer cells in the body (systemic chemotherapy).

Two or more medications are used at the same time in most situations, since one drug may maximize the influence of the other.

5-fluorouracil (5-FU) and mitomycin are the predominant combination of drugs used to treat anal cancer.
The 5-FU and cisplatin combination is also used, especially in people who are unable to get mitomycin or who have advanced anal cancer.

In these therapies, 5-FU is a substance that is applied 24 hours a day to the vein for 4 or 5 days. It’s put in a small pump that you can carry with you back home. On some other days in the treatment period, the other medications are administered more rapidly. And for at least 5 weeks, radiation is delivered 5 days a week.

Side effects of chemo

Chemo drugs attack rapidly dividing cells, which is why they act against cancer cells. But other cells in the body also divide rapidly, such as those in the bone marrow (where new blood cells are produced), the lining of the mouth and intestines, and the hair follicles. Chemo, too, is also likely to affect these cells, which can lead to side effects. Side effects depend on the amount of medications used the quantity taken and the period of treatment. Short-term side effects that are normal can include:

• Nausea and vomiting
• Loss of appetite
• Hair loss
• Diarrhea
• Mouth sores

Patients may have low blood cell counts because chemo can destroy the blood-producing cells of the bone marrow. This will lead to:

• An increased chance of infection (due to a shortage of white blood cells)
• Bleeding or bruising after minor cuts or injuries (due to a shortage of blood platelets)
• Fatigue or shortness of breath (due to low red blood cell counts).

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• September 2nd, 2020