Kerry was a 42-year old female executive who was in excellent health. She was married but had no children and had never been pregnant. She was a non-smoker with no past medical history and no family history of cancer. Specifically, Kerry had no history of sexually transmitted diseases and she was HIV negative. When she noticed blood on the toilet paper after her bowel movements, she first thought that the problem was due to hemorrhoids. However, after two weeks, the bleeding increased and was accompanied by pain and itching around the anus. She went to her primary doctor whose exam revealed a 2 x 2 inch mass at the anal sphincter. Her doctor did not feel any abnormal lymph nodes in her groin. He referred her to a colorectal surgeon who performed a colonoscopy. That examination confirmed the mass seen by her primary doctor but no other lesions. Biopsy revealed a squamous cell carcinoma, anal cancer.
After her diagnosis, Kerry’s surgeon sent her for a PET/CT scan which revealed abnormality only at the anal mass. There was no distant activity to suggest metastatic (distant, incurable) spread of her cancer. Her surgeon referred her to a radiation oncologist and medical oncologist. They recommended radiation therapy (RT) and chemotherapy delivered together (concurrent chemoRT) which she underwent over a period of 6 weeks. Kerry was treated with intensity modulated radiation therapy (IMRT) in order to minimize RT dose to critical organs including the small bowel and bladder, while treating potential microscopic cancer cells within the lymph nodes in her pelvis and groin and the anal tumor. She received concurrent mitomycin and fluorouracial chemotherapy by IV infusion as an outpatient. Kerry had expected side effects of treatment including severe irritation and redness of the skin in the groin and anus, but she did not require a break during IMRT. She had significant fatigue that kept her out of work during most of her chemoRT. She had some loose bowels which were well controlled after adjusting her diet. Near completion of her treatment, there was no evidence of any tumor remaining. She recovered from the side effects of treatment over about six weeks. Kerry has seen one of her cancer doctors every three to six months for the past five years and she remains cancer free!
Although it’s one of the least common cancers of the GI tract, there are still about 5000 cases of anal cancer diagnosed in the U.S. each year. There are more women than men diagnosed. The average age at diagnosis is around 60 years old, but it can occur in patients in their 30s and 40s. If the disease is localized, which is the case for 50% of patients, then the cure rate is roughly 80%.
RISKS & CAUSES
The majority of patients who are diagnosed with anal cancer don’t have a clearly defined risk factor. However, factors that increase the risk of developing anal cancer are associated with the risk of human papillomavirus (HPV) infection. This virus is the same kind that causes genital warts. Certain strains of the HPV virus are associated with a high risk of developing anal cancer as well as cervical cancer and some types of throat cancer. Activities that put people at risk for HPV, like receptive anal intercourse, also put them at risk of later developing anal cancer.
SIGNS & SYMPTOMS
Patients often present to their doctors with complaints of anal pain or bleeding. Many patients ignore or downplay the symptoms, often initially attributing them to hemorrhoids. While most people who have these symptoms don’t have anal cancer, persistent pain or bleeding should always prompt medical attention. Less commonly, patients will complain of itching or a painless mass in the groin. A lump can develop in the groin as a result of anal cancer spreading to lymph nodes and causing them to enlarge.
The diagnosis of anal cancer is usually made by biopsy of the anal mass or area of ulceration. Generally, this procedure is performed by a medical GI specialist or surgeon. These doctors are able to directly look into the anal canal and rectum by proctoscopy (or the entire colon by colonoscopy) with special instruments after they deliver medications to minimize discomfort. Biopsies are performed during these procedures, after sedation and/or injection of numbing medicine. Most anal cancers (80%) are squamous cell carcinomas. A thorough evaluation of someone suspected of having anal cancer should also include examination of the pelvis, particularly both groins. If lymph nodes are enlarged, then they may also be biopsied. Many enlarged lymph nodes are only inflamed, with no evidence of cancer. Blood tests that may be ordered include complete blood count, tests of kidney function, and possibly HIV testing, depending on the patients’ risk factors for the virus.
The American Joint Committee on Cancer (AJCC) TNM staging system is used to determine if anal cancer is localized (early stage) or has spread to other sites (advanced or late stage). Early stage disease is limited to the anus, while advanced disease refers to cancers that have invaded nearby organs or lymph nodes in the pelvis or groins. Imaging studies should include CT scan of the abdomen and pelvis and a chest X-ray at minimum. Staging may also include a PET/CT scan. This imaging test allows the radiologist as well as the treating cancer specialists to see if the anal cancer has spread to involve lymph nodes in the groin or pelvis, or metastasized to other sites in the body such as the liver or lungs.
The standard treatment for anal cancer doesn’t involve surgery, which comes as both a surprise and a relief to many patients. Since most anal cancers invade the sphincter that controls defecation, surgery to remove such a cancer would require removal of the sphincter and creation of a colostomy. Therefore, surgery is generally avoided in favor of treatment that will keep the anal sphincter intact. An exception would be very early cancers of the anal margin, on the skin outside the anus.
Concurrent chemoRT is the standard treatment for the majority of patients with anal cancer, to obtain the best chance of cure with sphincter preservation. RT delivered over roughly 6 weeks with concurrent IV fluorouracil (5FU) and mitomycin-C (MMC) chemotherapy provides patients the best chance for cure. RT is delivered in daily fractions using either 3D conformal RT or IMRT. The latter technique may be used in order to minimize the amount of normal bowel and/or genitalia receiving full-dose RT (& therefore minimize side effects).
The main side effects that are possible during RT to the anus and pelvis include skin reaction that may be severe around the anus and creases of skin at the groins, as well as bowel irritation and diarrhea. Most patients will have these acute symptoms resolve within 1-2 months following completion of treatment. Extremely rare (<1%) but serious side effects include bowel obstruction or fistula (a hole between the anus and bladder or urethra). 5FU may also cause bowel irritation, diarrhea, irritation in the mouth or lips, poor appetite, and fatigue. Uncommonly, skin or nail discoloration or severe peeling of the hands and feet (hand foot syndrome) or other major side effects can happen. In rare cases, heart problems including heart attack can occur. MMC may cause decrease in blood counts, mouth sores, poor appetite, and fatigue. Nausea, vomiting, and urinary irritation may also occur. Rarely, life-threatening lung or kidney damage can occur.