Stage 3 anal cancer is a diagnosis that means the cancer has not spread to distant parts of the body, but it has either grown into nearby organs like the bladder, vagina, or urethra, or spread to nearby lymph nodes, or both. Understanding this stage can help patients and their families prepare for treatment and know what to expect.
What Does Stage 3 Anal Cancer Mean?
When doctors diagnose stage 3 anal cancer, they are describing a cancer that has grown beyond the original area but has not reached distant organs. Stage 3 is divided into three subcategories, called 3A, 3B, and 3C, each describing different patterns of how the cancer has spread.[1]
In stage 3A, the cancer is no bigger than 5 centimeters and has spread to nearby lymph nodes, which are small bean-shaped structures that help fight infection and filter out harmful substances. These lymph nodes may be in the rectum, pelvis, or groin area. However, the cancer has not spread to other parts of the body.[1]
Stage 3B means the cancer can be any size and has grown into surrounding organs such as the bladder, urethra (the tube through which urine leaves the body), or vagina. In this subcategory, the cancer has not yet spread to nearby lymph nodes or any other parts of the body.[1]
Stage 3C describes two possible situations. In one case, the cancer is larger than 5 centimeters and has spread to nearby lymph nodes but has not grown into surrounding organs. In the other case, the cancer of any size has grown into organs such as the urethra, vagina, or bladder and has also spread to nearby lymph nodes.[1]
Doctors use the TNM staging system to determine these categories. TNM stands for tumor, node, and metastasis. The letter T describes the size of the tumor, N describes whether cancer cells are in nearby lymph nodes, and M describes whether the cancer has spread elsewhere in the body. The number staging system combines these details to give an overall stage.[1]
Understanding Anal Cancer
Anal cancer is a type of cancer that forms in the tissues of the anus, which is the end of the large intestine where solid waste leaves the body. The anus is formed partly from the outer skin layers of the body and partly from the intestine. It is connected to the rectum by the anal canal, which is about 1 to 1.5 inches long. This area is controlled by two ring-like sphincter muscles that contract to hold stool in and relax to allow it to pass out of the body.[5]
Most anal cancers are related to infection with human papillomavirus, or HPV. This is a common virus that can be passed from person to person through sexual contact. More than 90% of people with a diagnosis of anal cancer are positive for HPV.[2]
The most common type of anal cancer is squamous cell cancer, which starts in the flat, thin cells that line the anal canal. The staging information discussed here applies specifically to squamous cell anal cancer, which is the type most patients are diagnosed with.[1]
Causes of Anal Cancer
Anal cancer is caused by certain changes to the way cells function, especially how they grow and divide into new cells. Most anal cancers are related to infection with high-risk types of HPV, particularly HPV type 16 or 18. HPV causes changes in the cells that can lead to cancer over time.[5]
The virus is spread through sexual contact, including anal intercourse. While many people are infected with HPV at some point in their lives, most do not develop cancer. The body’s immune system usually clears the infection before it causes problems. However, when the infection persists for many years, it can lead to changes in cells that eventually become cancerous.[5]
Risk Factors for Anal Cancer
A risk factor is anything that increases the chance of getting a disease. Some risk factors for anal cancer can be changed, while others, such as genetics or getting older, cannot. Having one or more risk factors does not mean that a person will definitely get anal cancer. Many people with risk factors never develop the disease, while others with no known risk factors do.[5]
The main risk factors for anal cancer include being infected with high-risk HPV, especially types 16 or 18. Having a condition or disease that weakens the immune system, such as HIV or having received an organ transplant, also increases risk. People who have had an organ transplant often take medications that suppress the immune system to prevent organ rejection, and this can increase cancer risk.[5]
Having a personal history of vulvar, vaginal, or cervical cancers increases the risk of anal cancer. These cancers are also often caused by HPV infection. Having many sexual partners or having receptive anal intercourse also raises the risk because these behaviors increase the chance of HPV infection.[5]
Smoking cigarettes is another important risk factor for anal cancer. Chemicals in tobacco smoke damage cells throughout the body, including cells in the anal area. Smokers are more likely to develop anal cancer than non-smokers, and quitting smoking can help reduce this risk.[5]
Symptoms of Anal Cancer
The signs and symptoms of anal cancer can be caused by the cancer itself or by other conditions. It is important to check with a doctor if any concerning symptoms appear. Common symptoms include bleeding from the anus or rectum. This bleeding may appear as bright red blood on toilet paper or in the toilet bowl after a bowel movement.[5]
A lump near the anus is another possible sign. Some people notice a growth or mass in or around the anal area. Pain or pressure in the area around the anus can also occur, making it uncomfortable to sit or have bowel movements.[5]
Itching or discharge from the anus may develop. This discharge can be mucus or pus and may have an unusual odor. A change in bowel habits, such as having narrower stools than usual or feeling like the bowel does not empty completely, can also be a symptom of anal cancer.[5]
These symptoms can also be caused by other conditions such as hemorrhoids, anal fissures, or infections. However, anyone experiencing these symptoms should see a doctor for proper evaluation and diagnosis.[5]
Prevention of Anal Cancer
While not all cases of anal cancer can be prevented, there are steps people can take to reduce their risk. Getting vaccinated against HPV is one of the most effective ways to prevent anal cancer. The HPV vaccine protects against the types of HPV that most commonly cause cancer. It is most effective when given before a person becomes sexually active, but it can still provide some protection even after exposure to HPV.[5]
Practicing safer sex, including using condoms during sexual activity, can reduce the risk of HPV infection. While condoms do not provide complete protection against HPV because the virus can infect skin not covered by a condom, they do reduce the risk of transmission.[5]
Quitting smoking is important for reducing the risk of anal cancer. Tobacco use increases the risk of many types of cancer, including anal cancer. People who need help quitting can talk to their doctor about smoking cessation programs and medications that can make it easier to stop.[5]
People with weakened immune systems, such as those with HIV, should work with their healthcare providers to manage their condition and keep their immune system as strong as possible. Regular medical care and taking medications as prescribed can help reduce cancer risk.[5]
How the Body Changes with Anal Cancer
Anal cancer causes changes in the normal structure and function of the anal area. As cancer cells grow and multiply, they form a mass or tumor. This tumor can start in the lining of the anal canal or in the skin around the outside of the anus. As the tumor grows, it takes up space and can interfere with normal bowel function.[5]
The cancer can grow into nearby tissues and organs. In stage 3B, the tumor may invade the bladder, urethra, or vagina. When cancer grows into these organs, it can cause symptoms related to those structures, such as pain during urination, blood in the urine, or vaginal bleeding or discharge.[1]
Cancer cells can also spread to nearby lymph nodes. Lymph nodes are part of the body’s immune system and help filter out harmful substances. When cancer cells break away from the main tumor, they can travel through lymphatic vessels to nearby lymph nodes. Once in the lymph nodes, the cancer cells can continue to grow and form new tumors. This is what happens in stage 3A and 3C anal cancer.[1]
The presence of cancer in lymph nodes means the cancer has started to spread beyond its original location, but it has not yet reached distant organs like the liver or lungs. This distinction is important because cancer that has spread to distant organs is classified as stage 4 and requires different treatment approaches.[1]
Treatment for Stage 3 Anal Cancer
The main treatment for stage 3 anal cancer is chemoradiotherapy, which means receiving both chemotherapy and radiation therapy at the same time. This combined approach is effective at destroying cancer cells while preserving the sphincter muscles that control bowel movements. If these muscles can be saved, patients will have a better quality of life after treatment because they will be able to have bowel movements normally.[4]
Chemotherapy uses anti-cancer drugs to destroy cancer cells. These drugs, also called cytotoxic drugs, circulate throughout the body in the bloodstream and can reach cancer cells wherever they are. The chemotherapy drugs most commonly used for stage 3 anal cancer are fluorouracil, also called 5-fluorouracil or 5-FU, and mitomycin. Sometimes capecitabine is used instead of fluorouracil. Chemotherapy is typically given every 3 weeks.[4]
Radiation therapy uses high-energy waves similar to x-rays to kill cancer cells. External radiation therapy is usually given once a day, 5 days a week, for 5 to 6 weeks. Extra radiation doses, called a radiation boost, may also be given to target any remaining cancer cells.[4]
When treatment is finished, doctors check to make sure the cancer has completely gone. Unfortunately, chemoradiotherapy is not suitable for everyone. Doctors will talk to patients about other options if they feel chemoradiotherapy is not the best treatment for their situation.[1]
Some people diagnosed with anal cancer may have an anal fistula, which is an abnormal opening or passage between the anus and the surrounding skin. If a patient has an anal fistula, they will need surgery to repair it before starting chemoradiotherapy for stage 3 anal cancer.[4]
If chemoradiotherapy does not destroy all the cancer cells, the healthcare team may offer surgery to remove the rest of the cancer. This is called salvage surgery. If doctors think there may still be cancer left after chemoradiotherapy, they take a sample of tissue, called a biopsy, from the area. If this sample contains cancer cells, they will talk to the patient about further treatment.[1]
One type of salvage surgery is called abdominoperineal resection, or APR. This is a large operation that removes the rectum, anal sphincter, anus, and muscles around the anus. After this surgery, patients will need a permanent colostomy, which means waste will exit the body through an opening in the abdomen into a bag worn on the outside of the body. The surgeon and anesthetist will make sure the patient is well enough to have this surgery before proceeding.[1]
Another type of surgery is inguinal lymph node dissection, which may be used to treat stage 3B anal cancer when it has spread to lymph nodes in the groin. This surgery removes the affected lymph nodes to help control the spread of cancer.[4]
Outlook and Survival
Most people with stage 3 anal cancer live at least 5 years after diagnosis. Doctors often consider cancer cured if there are no signs of the disease for at least 5 years. The chances of curing anal cancer are generally best in people who are younger or are in better overall health.[2]
The National Cancer Institute and American Cancer Society use a different staging system for reporting survival statistics. They classify anal cancer as localized (contained to the anus), regional (spread to nearby structures or lymph nodes), or distant (spread to distant body parts). Stage 3 anal cancer generally falls into the regional category.[2]
After treatment, patients will need regular follow-up care to monitor for any signs that the cancer has returned. Follow-up visits typically include physical examinations and may include imaging tests or other procedures to check for cancer recurrence. The frequency of these visits depends on individual circumstances, but they are usually more frequent in the first few years after treatment.[1]
