How do health care professionals make a diagnosis of anal cancer?
If a doctor suspects that a patient has anal cancer, the examining health care professional will first take a medical history and conduct a physical exam, including both inspection of the anal area and a digital rectal exam in which a gloved finger is inserted through the anus and into the rectum. Next, the anal canal can be examined with an anoscope -- a short, lubricated tube with a light on it. The physician can see and inspect the anus, anal canal, and lower rectum with the anoscope. A proctoscopy exam with a flexible endoscope also may be used with less discomfort. Other types of scopes, both rigid and flexible, examine the lower colon, rectum, and anal regions. Their use is called endoscopy. Endo-anal or endo-rectal ultrasound (ultrasound probe insertion into the rectum) can detect abnormal rectal structures and the extent of spread.
A diagnosis of cancer is only definitively made by a physician called a pathologist who analyzes tissue in a laboratory. The tissue is obtained by biopsy, which refers to the technique of removing a piece of the abnormal appearing or suspicious tissue. This is done under direct visualization either with or through an endoscope, or if directly visible, using a type of biopsy needle under local anesthesia.
The pathologist analyzes the tissue and creates a report describing the type of cancer and its extent within the biopsy specimen.
How do health care professionals determine anal cancer staging?
Staging defines the extent of the primary cancerous tumor as well as the presence or absence and extent or spread of the cancer. This staging classification helps the patient's doctors to decide on the best approach to treatment. Staging also helps to estimate the patient's likelihood of survival or prognosis. Finally, it allows doctors who treat these diseases to more accurately compare the results of treatment using various techniques. Such comparisons require that the doctors treat the same extent of cancer from the outset to make their conclusions valid.
By convention, the stage of the cancer is described using the TNM system as described by the International Union Against Cancer and in the AJCC Cancer Staging Manual. T describes the extent of the tumor. N denotes the presence, or absence, and extent of lymph node metastases. M refers to the presence or absence of distant metastases. Anal cancer stages are as follows:
- TX: Primary tumor cannot be assessed
- T0: No evidence of primary tumor
- T1s: Carcinoma in situ (for example, Bowen's disease, high grade squamous intraepithelial lesion, and anal intraepithelial neoplasia II to III)
- T1: Tumor less than or equal to 2 cm in greatest dimension
- T2: Tumor greater than 2 cm but less than 5 cm in greatest dimension
- T3: Tumor greater than 5 cm in greatest dimension
- T4: Tumor of any size which invades adjacent organ(s), for example, vagina, urethra, bladder
- NX: Regional lymph nodes cannot be assessed
- N0: No regional lymph node metastases
- N1: Metastases present in perirectal lymph node(s)
- N2: Metastases in unilateral internal iliac and/or inguinal lymph node(s)
- N3: Metastases in perirectal and inguinal lymph nodes and/or bilateral internal iliac and/or inguinal lymph nodes
- M0: No distant metastases
- M1: Distant metastases present
Consequently, stages can be written in detail as shown in the examples below with the cancer stage increasing in aggressiveness as the stages progress from 0 to IV:
- 0: T1sN0M0
- I: T1N0M0
- II: T2N0M0, T3N0M0
- IIIA: T13N1M0
- IIIB: T4N1M0, any T, N2, or N3M0
- IV: Any T, any N, M1
What types of health care professionals diagnose and treat anal cancer?
Anal cancers often need a team of health care professionals that collaborate in the treatment of anal cancers. Usually the doctors on a person's team work out of the same institution or hospital and have had experience in treating cancer patients together. Team members often include two or more of the following doctors:
- Primary care physician (PCP)
- General surgeon (best if he or she has special training in colon and rectal disease surgery
- Radiation oncologist
- Medical oncologist
These physicians will be able to design a specific treatment protocol that best suits the patient and his or her cancer.
What is the medical treatment for anal cancer?
Anal cancer treatment involves a variety of therapies including surgery, radiation, chemotherapy, or a combination of these.
What is the prognosis for anal cancer?
Anal cancer is usually curable when found localized. Early detection remains the key to long-term survival as it is in many forms of cancer. The 5-year survival rates by anal cancer stage and cell type include:
- Squamous cell: 71% for stage I, 64% for stage II, 48% for stage IIIA, 43% for stage IIIB, and 21% for stage IV
- Non-squamous: 59% for stage I, 53% for stage II, 38% for stage IIIA, 24% for stage IIIB, and 7% for stage IV
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Edge, S.B., et al. "Anal Cancer." AJCC Cancer Staging Manual, 7th Ed. New York, NY: Springer, 2010.
"NCCN Clinical Practice Guidelines in Oncology: Anal Carcinoma." Version 1.2017.
"PDQ National Cancer Institute Summaries: Anal Cancer." 2017.