Anal cancer is a cancer (malignant tumor) which arises from the anus, the distal opening of the gastrointestinal tract. It is a distinct entity from the more common colorectal cancer.
Anal cancer is typically an anal squamous cell carcinoma that arises near the squamocolumnar junction, often linked to human papillomavirus (HPV) infection. It may be keratinizing (basaloid) or non-keratinizing (cloacogenic). Other types of anal cancer are adenocarcinoma, lymphoma, sarcoma or melanoma. From data collected 2004-2010, the relative five year survival rate in the United States is 65.5%, though individual rates may vary depending upon the stage of cancer at diagnosis and the response to treatment.
Signs and Symptoms
Symptoms of anal cancer can include pain or pressure in the anus or rectum, a change in bowel habits, a lump near the anus, rectal bleeding, itching or discharge. Bleeding may be severe.
- Human papillomavirus: Examination of squamous cell carcinoma tumor tissues from patients in Denmark and Sweden showed a high proportion of anal cancers to be positive for the types of HPV that are also associated with high risk of cervical cancer. In another study done, high-risk types of HPV, notably HPV-16, were detected in 84 percent of anal cancer specimens examined. Based on the study in Denmark and Sweden, Parkin estimated that 90% of anal cancers are attributable to HPV.
- Sexual activity: Having multiple sex partners due to the increased risk of exposure to HPV. Receptive anal intercourse, whether male or female, increases the chances of anal cancer sevenfold due to HPV. Those who engage in anal intercourse with multiple partners are 17 times more likely to develop anal cancer than those who do not.
- Smoking: Current smokers are several times more likely to develop anal cancer compared with nonsmokers. Epidemiologist Janet Daling, Ph.D., a member of Fred Hutchinson’s Public Health Sciences Division, and her team found that smoking appears to play a significant role in anal-cancer development that is independent of other behavioral risk factors, such as sexual activity. More than half of the anal-cancer patients studied were current smokers at the time of diagnosis, as compared to a smoking rate of about 23 percent among the controls. “Current smoking is a very important promoter of the disease,” said Daling. “There’s a fourfold increase in risk if you’re a current smoker, regardless of whether you’re male or female.” They explained that the mechanism behind smoking and anal-cancer development is unknown, but researchers speculate that smoking interferes with a process called apoptosis, or programmed cell death, which helps rid the body of abnormal cells that could turn cancerous. Another possibility is that smoking suppresses the immune system, which can decrease the body’s ability to clear persistent infection or abnormal cells.
- Immunosuppression, which is often associated with HIV infection.
- Benign anal lesions.
- A history of cervical, vaginal or vulval cancers.
- Cloacogenic. Cloacogenic carcinoma is a rare tumor of the anorectal region originating from a persistent remnant of the cloacal membrane of the embryo. The tumor accounts for 2-3% of anorectal carcinomas and occurs more than twice as often in women.
Anal Cancer Treatment
Localised disease (carcinoma-in-situ) and the precursor condition, anal intraepithelial neoplasia (anal dysplasia or AIN) can be ablated with minimally invasive methods such as Infrared Photocoagulation.
Previously, anal cancer was treated with surgery, and in early stage disease (i.e., localised cancer of the anus without metastasis to the inguinal lymph nodes), surgery is often curative. The difficulty with surgery has been the necessity of removing the internal and external anal sphincter, with concomitant fecal incontinence. For this reason, many patients with anal cancer have required permanent colostomies.
Current gold-standard therapy is chemotherapy and radiation treatment to reduce the necessity of debilitating surgery. This “combined modality” approach has led to the increased preservation of an intact anal sphincter, and therefore improved quality of life after definitive treatment. Survival and cure rates are excellent, and many patients are left with a functional sphincter. Some patients have fecal incontinence after combined chemotherapy and radiation. Biopsies to document disease regression after chemotherapy and radiation were commonly advised, but are not as frequent any longer. Current chemotherapy consists of continuous infusion 5-FU over four days with bolus mitomycin given concurrently with radiation. 5-FU and cisplatin are recommended for metastatic anal cancer.
Metastatic or recurrent disease
10 to 20% of patients treated for anal cancer will develop distant metastatic disease following treatment. Metastatic or recurrent anal cancer is difficult to treat, and usually requires chemotherapy. Radiation is also employed to palliate specific locations of disease that may be causing symptoms. Chemotherapy commonly used is similar to othersquamous cell epithelial neoplasms, such as platinum analogues, anthracyclines such as doxorubicin, and antimetabolites such as 5-FU and capecitabine. J.D. Hainsworth developed a protocol that includes Taxol and Carboplatinum along with 5-FU. Median survival rates for patients with distant metastases ranges from 8 to 34 months.
What Is Anal Cancer?
Anal cancer occurs in the anus, the end of the gastrointestinal tract. Anal cancer is very different from colorectal cancer, which is much more common. Anal cancer’s causes, risk factors, clinical progression, staging and treatment are all very different from colorectal cancer. Anal cancer is a lump which is created by the abnormal and uncontrolled growth of cells in the anus.
Anal cancer is very rare. According to the American Cancer Society, there were an estimated 7,270 new cases of anal cancer in the USA in 2014 (a rise from 5,070 in 2008). Of these, 4,630 were women and 2,640 were men. Approximately 1,010 people died from anal cancer in the USA in 2014.
Reports suggest that the incidence of this type of cancer is rising. The number of anal cancer cases is increasing in both sexes, particularly among American men, and changing trends in sexual behavior – combined with current tobacco use and infection by a specific strain of the human papillomavirus – may help explain the increase, as this article explains.
Most anal cancer patients are diagnosed in their early 60s. Anal cancer is more common among women, men who receive anal intercourse, and people with weakened immune systems. Experts say that anal cancer is closely associated with some HPV (human papilloma virus) strains.
The anus, the anal canal and squamous cell carcinomas
The anal canal is lined with squamous cells – flat cells that look like fish scales under the microscope. The majority of anal cancers develop from these squamous cells. Such cancers are known as squamous cell carcinomas.
The point at which the anal canal meets the rectum is called the transitional zone. The transitional zone has squamous cells and glandular cells – these produce mucus which helps the stool (feces) pass through the anus smoothly. Adenocarcinoma (type of cancer) of the anus can develop from these glandular cells. However, squamous cell carcinomas make up the vast majority of anal cancers.
Symptoms of anal cancer
Common symptoms of anal cancer may include:
- Rectal bleeding – the patient may notice blood on feces or toilet paper.
- Pain in the anal area.
- Lumps around the anus. These are frequently mistaken for piles (hemorrhoids).
- Mucus discharge from the anus.
- Jelly-like discharge from the anus.
- Anal itching.
- Change in bowel movements. This may include diarrhea, constipation, or thinning of stools.
- Fecal incontinence (problems controlling bowel movements).
- Women may experience lower back pain as the tumor exerts pressure on the vagina.
- Women may experience vaginal dryness.
Causes of anal cancer
Experts cannot comprehensively say what causes anal cancer. However, the following are considered as possible risk factors:
- HPV (human papilloma virus) – some types of HPV are closely linked to anal cancer. Approximately 80% of patients with anal cancer are infected in the anal area with a HPV.
- Sexual partner numbers – this is also linked to HPV. The more sexual partners somebody has (or has had) the higher are the chances of being infected with HPV, which is closely linked to anal cancer risk.
- Receptive anal intercourse – both men and women who receive anal intercourse have a higher risk of developing anal cancer. HIV-positive men who have sex with men are up to 90 times more likely than the general population to develop anal cancer, this study revealed.
- Other cancers – women who have had vaginal or cervical cancer, and men who have had penile cancer are at higher risk of developing anal cancer. This is also linked to HPV infection.
- Age – the older somebody is the higher is his/her risk of developing anal cancer. In fact, this is the case with most cancers.
- A weak immune system – people with a weakened immune system have a higher risk of developing anal cancer. This may include people with HIV/AIDS, patients who have had transplants and are taking immunosuppressant medications.
- Smoking – smokers are significantly more likely to develop anal cancer compared to non-smokers. In fact, smoking raises the risk of developing several cancers.
- Benign anal lesions – IBD (irritable bowel disease), hemorrhoids, fistulae or cicatrices. Inflammation resulting from benign anal lesions may increase a person’s risk of developing anal cancer.
Diagnosis of anal cancer
The first person to see will probably be a GP (general practitioner, primary care physician). The GP will ask the patient about his/her symptoms and carry out an examination. The doctor will also need to know about the patient’s medical history. Then the patient will be referred to a colorectal surgeon – this is a doctor who specializes in bowel conditions. Colorectal surgeons are sometimes called proctologists. The specialist may carry out the following tests:
A rectal examination
This may be a bit uncomfortable, but is not painful. A proctoscope or sigmoidoscope may be used – an instrument that allows the doctor to examine the area in more detail. In some countries this device is called an anoscope, and the procedure ‘anoscopy’. The examination will determine whether the patient needs a biopsy.
A small sample of tissue is taken from the anal area and sent to the lab for testing. Tissue will be examined under a microscope.
If cancerous tissue is detected after the biopsy the patient will need further tests to find out how advanced (big) the cancer is and whether or not it has spread. The following tests may be done:
- CT (computerized tomography) scan – X-rays are used to create a 3-dimensional picture of the target area.
- MRI (magnetic resonance imaging) scan – magnets and radio waves produce 2-dimensional and 3-dimensional pictures of the target area.
- Ultrasound scan – sound waves are used to create an image of the target area. This could be done internally with a rectalultrasound – the instrument is inserted into the anus before the scanning begins.
Treatments for anal cancer
Treatment for anal cancer will depend on various factors, including how big the tumor is, whether or not it has spread, where it is, and the general health of the patient. If the tumor is small it can be removed surgically, and that’s it.
The type of surgery a patient will require depends on the size and position of the tumor.
This removes a small tumor and some surrounding tissue. This type of surgery can only be carried out if the anal sphincter is not sacrificed. Patients who undergo a resection do not have their ability to pass a bowel movement affected.
The anus, rectum and a section of the bowel are surgically removed. The patient will need a colostomy – the end of the bowel is brought out onto the skin on the surface of the abdomen. A bag is placed over the stoma – the opening of the bowel – and collects the stools (feces) outside the patient’s body. Although this sounds shocking, people with colostomies can lead normal lives, play sports and have active sex lives.
Chemotherapy and radiotherapy
In most cases, the patient will probably have to undergo chemotherapy and/or radiotherapy.
Radiotherapy combined with chemotherapy treatments (chemoradiation) are commonly used to destroy the anal cancer cells. Treatments are either given simultaneously or consecutively. This combined therapy approach has led to a much higher percentage of patients with an intact anal sphincter – survival and cure rates are good.
Chemotherapy uses cytotoxic drugs (antineoplastics) – cytotoxic drugs prevent the cancer cells from dividing. They are administered either by injection or orally.
Radiotherapy uses high-energy rays that destroy the cancer cells. This can be given by an external beam or internally (brachytherapy).
Radiotherapy has side effects, as does chemotherapy. When the treatment is combined the side effects may be more acute. Side effects may include:
- Soreness and blistering around the target area (anus)
- A higher susceptibility to infections during treatment
- Low white blood cell count (which raises infection risk)
- Loss of appetite
- Nausea or vomiting
- Mouth ulcers
- Sore mouth
- Loss of hair
- Narrowing and dryness of the vagina
- Anemia (low red blood cell count)
- Low platelet count which raises risk of bruising or bleeding
- Dry skin
- Muscle and nerve problems
- Excessive coughing, sometimes breathing difficulties
- Fertility problems.
Prevention of anal cancer
Although anal cancer is already very rare, there are some recommendations that can help reduce your risk further. These include:
- Reduce your chances of being infected with HPV
- Use condoms when having sex
- Limit the numbers of sexual partners
- Abstain from anal intercourse
- Quit smoking.
Anal Cancer – Symptoms and Causes
Anal cancer signs and symptoms include:
- Bleeding from the anus or rectum
- Pain in the area of the anus
- A mass or growth in the anal canal
- Anal itching
When to see a doctor
Talk to your doctor about any signs and symptoms that bother you, especially if you have any factors that increase your risk of anal cancer.
Anal cancer forms when a genetic mutation turns normal, healthy cells into abnormal cells. Healthy cells grow and multiply at a set rate, eventually dying at a set time. Abnormal cells grow and multiply out of control, and they don’t die. The accumulating abnormal cells form a mass (tumor). Cancer cells invade nearby tissues and can separate from an initial tumor to spread elsewhere in the body (metastasize).
Anal cancer is closely related to a sexually transmitted infection called human papillomavirus (HPV). Evidence of HPV is detected in the majority of anal cancers. HPV is thought to be the most common cause of anal cancers.
Several factors have been found to increase the risk of anal cancer, including:
- Older age. Most cases of anal cancer occur in people age 50 and older.
- Many sexual partners. People who have many sexual partners over their lifetimes have a greater risk of anal cancer.
- Anal sex. People who engage in anal sex have an increased risk of anal cancer.
- Smoking. Smoking cigarettes may increase your risk of anal cancer.
- History of cancer. Those who have had cervical, vulvar or vaginal cancer have an increased risk of anal cancer.
- Human papillomavirus (HPV). HPV infection increases your risk of several cancers, including anal cancer and cervical cancer. HPV infection is a sexually transmitted infection that can also cause genital warts.
- Drugs or conditions that suppress your immune system. People who take drugs to suppress their immune systems (immunosuppressive drugs), including people who have received organ transplants, may have an increased risk of anal cancer. HIV — the virus that causes AIDS — suppresses the immune system and increases the risk of anal cancer.
Anal cancer rarely spreads (metastasizes) to distant parts of the body. Only a small percentage of tumors are found to have spread, but those that do are especially difficult to treat. Anal cancer that metastasizes most commonly spreads to the liver and the lungs.
Tests and procedures used to diagnose anal cancer include:
- Examining your anal canal and rectum for abnormalities. During a digital rectal exam, your doctor inserts a gloved, lubricated finger into your rectum. He or she feels for anything unusual, such as growths.
- Visually inspecting your anal canal and rectum. Your doctor may use a short, lighted tube (anoscope) to inspect your anal canal and rectum for anything unusual.
- Taking sound wave pictures (ultrasound) of your anal canal. To create a picture of your anal canal, your doctor inserts a probe, similar to a thick thermometer, into your anal canal and rectum. The probe emits high-energy sound waves, called ultrasound waves, which bounce off tissues and organs in your body to create a picture. Your doctor evaluates the picture to look for anything abnormal.
- Removing a sample of tissue for laboratory testing. If your doctor discovers any unusual areas, he or she may take small samples of affected tissue (biopsy) and send the samples to a laboratory for analysis. By looking at the cells under a microscope, doctors can determine whether the cells are cancerous.
Once it’s confirmed that you have anal cancer, your doctor works to determine the size of the cancer and whether it has spread — a process called staging. Determining your cancer’s stage helps your doctor determine the best approach to treating your cancer.
Tests and procedures used in the staging of your cancer may include:
- Computerized tomography (CT) scan
- Magnetic resonance imaging (MRI)
- Positron emission tomography (PET)
Your doctor uses the information from the procedures to assign your cancer a stage. The stages of anal cancer are:
- Stage I. Anal cancer is 2 centimeters (about 3/4 inch) or less — about the size of a peanut or smaller.
- Stage II. Anal cancer is larger than 2 centimeters (about 3/4 inch), but has not spread beyond the anal canal.
- Stage IIIA. Anal cancer is any size and has spread either to lymph nodes near the rectum or to nearby areas, such as the bladder, urethra or vagina.
- Stage IIIB. Anal cancer is any size and has spread to nearby areas and lymph nodes, or it has spread to other lymph nodes in the pelvis.
- Stage IV. Anal cancer has spread to parts of the body away from the pelvis.
Treatment for Anal Cancer
What treatment you receive for anal cancer depends on the stage of your cancer, your overall health and your own preferences.
Combined chemotherapy and radiation
Doctors usually treat anal cancer with a combination of chemotherapy and radiation. Combined, these two treatments enhance each other and improve chances for a cure.
- Chemotherapy. Chemotherapy drugs are injected into a vein or taken as pills. The chemicals travel throughout your body, killing rapidly growing cells, such as cancer cells. Unfortunately they also damage healthy cells that grow rapidly, including those in your gastrointestinal tract and in your hair follicles. This causes side effects such as nausea, vomiting and hair loss.
- Radiation therapy. Radiation therapy uses high-powered beams, such as X-rays and protons, to kill cancer cells. During radiation therapy, you’re positioned on a table and a large machine moves around you, directing radiation beams to specific areas of your body to target your cancer.Radiation may damage healthy tissue near where the beams are aimed. Side effects may include skin redness and sores in and around your anus, as well as hardening and shrinking of your anal canal.
You typically undergo radiation therapy for anal cancer for five or six weeks. Chemotherapy is typically administered during the first week and the fifth week. Your doctor tailors your treatment schedule based on characteristics of your cancer and your overall health.
Though combining chemotherapy and radiation increases the effectiveness of the two treatments, it also makes side effects more likely. Discuss with your doctor what side effects to expect.
Doctors typically use different procedures to remove anal cancer based on the stage of the cancer:
- Surgery to remove early-stage anal cancers. Very small anal cancers may be removed through surgery. During this procedure, the surgeon removes the tumor and a small amount of healthy tissue that surrounds it.Because the tumors are small, early-stage cancers can sometimes be removed without damaging the anal sphincter muscles that surround the anal canal. Anal sphincter muscles control bowel movements, so doctors work to keep the muscles intact.Depending on your cancer, your doctor may also recommend chemotherapy and radiation after surgery.
- Surgery for late-stage anal cancers or anal cancers that haven’t responded to other treatments. If your cancer hasn’t responded to chemotherapy and radiation, or if your cancer is advanced, your doctor may recommend a more extensive operation called abdominoperineal resection, which is sometimes referred to as an AP resection. During this procedure the surgeon removes the anal canal, rectum and a portion of the colon. The surgeon then attaches the remaining portion of your colon to an opening (stoma) in your abdomen through which waste will leave your body and collect in a colostomy bag.
Supportive (palliative) care
Palliative care is specialized medical care that focuses on providing relief from pain and other symptoms of a serious illness. Palliative care specialists work with you, your family and your other doctors to provide an extra layer of support that complements your ongoing care. Palliative care can be used while undergoing other aggressive treatments, such as surgery, chemotherapy or radiation therapy.
When palliative care is used along with all of the other appropriate treatments, people with cancer may feel better and live longer.
Palliative care is provided by a team of doctors, nurses and other specially trained professionals. Palliative care teams aim to improve the quality of life for people with cancer and their families. This form of care is offered alongside curative or other treatments you may be receiving.
Alternative medicine treatments can’t cure anal cancer. But some alternative medicine treatments may help you cope with the side effects of cancer treatment. Your doctor can treat many side effects, but sometimes medications aren’t enough. Alternative treatments can complement your doctor’s treatments and may offer additional comfort.
Options for common side effects include:
- Anxiety — massage, meditation, hypnosis, music therapy, exercise or relaxation techniques
- Fatigue — gentle exercise or tai chi
- Nausea — acupuncture, hypnosis or music therapy
- Pain — acupuncture, massage, music therapy or hypnosis
- Sleep problems — yoga or relaxation techniques
While these options are generally safe, talk with your doctor first to be sure that alternative medicine options won’t interfere with your cancer treatment.