Anal Cancer

  • Medical Author: Jay B. Zatzkin, MD, FACP
  • Medical Editor: Charles Patrick Davis, MD, PhD
    Charles Patrick Davis, MD, PhD

    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

Quick GuideSTD Diagnosis, Images, Symptoms, Treatment

STD Diagnosis, Images, Symptoms, Treatment

How do health care professionals make a diagnosis of anal cancer?

If a patient is suspected to have 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 tool. Other types of scopes, both rigid and flexible, can be used to 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) may be used to detect abnormal rectal structures.

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.

Staging techniques include direct visualization and measurement of the cancer and imaging techniques which can include standard X-rays as well as, ultrasound, CAT scan, MRI, and PET scans.

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
Medically Reviewed by a Doctor on 4/28/2017

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