Treatment of Anal Cancer

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Anal Canal is about 3 to 4 cm long terminal constricted part of the large intestine that lies between the rectum and the anus (outer opening for defecation). It serves as the passage for feces stored in the rectum to the outside of the body through the anus. It is lined with mucosa partly made-up of glandular epithelial cells (in the interior of the anal canal that is a continuation of rectum lining) and mainly consisting of squamous epithelial cells (that cover the interior part of the anal canal and are in continuation with the perianal skin). The junction of 2 types of cells is known as the transitional zone.

Anal Cancer Pretreatment Investigations

Anoscopy

anal cancer diagnosis by anoscopy

Anoscopy is a diagnostic technique which uses an anoscope – a cylindrical device equipped with a light source, and some special instruments for biopsy or surgery. This enables the doctors to closely examine the surface of the anal canal to determine the presence of cancerous or precancerous lesions. The physician can also collect biopsy sample{s} if an abnormal area is observed during the procedure.

Anal Biopsy

biopsy for anal tumor

Biopsy sample(s) from the anal region or the affected lymph nodes are generally collected in case an abnormal area(s) is observed during the anoscopy procedure or during the physical examination indicating enlarged lymph nodes. It can provide information such as the type of cancer, the severity of cancerous changes involved (grade of cancer), and the presence of specific defective genes or proteins.

Imaging Tests

One or more of the following investigations are required for staging and reassessment following treatment-

Transrectal Ultrasound

transrectal ultrasound by resectoscope

In normal ultrasound, a transducer is used which directs very high-frequency sound waves towards the tissue to be examined. In transrectal ultrasound, the transducer is placed directly into the rectum. This helps the doctor to examine the nearby tissue for any abnormality. This test can detect solid tumor masses (cancerous) within the anus or nearby area(s), which can be further evaluated with the help of other diagnostic tools.

  • Computed tomography (CT) scan
  • Positron emission tomography (PET) scan
  • Magnetic resonance imaging (MRI) scan

Anal Cancer Treatment based on Staging

The anal cancer treatment may depends on various factors including stage of the disease, age, performance status of the patient, patient’s preference along with other factors.

Stage 0 (Tis N0 M0)

Stage 0 is presence of pre-cancerous cells (CIS or high-grade AIN) found only in the surface layer of the anal canal. No evidence of primary tumor mass.

Stage 0 anal cancer can be treated by removal of the pre-cancerous lesion by local excision with the negative margins

Stage I and II (T1-3 N0 M0)

Stage I (T1 N0 M0)

The primary tumor is </=2 cm in size. No spread to nearby lymph nodes or distant body parts.

Stage IIA (T2 N0 M0)

The primary tumor is >2 cm but </=5 cm in size. No spread to nearby lymph nodes or distant body parts.

Stage IIB (T3 N0 M0)

The primary tumor is >5 cm in size. No spread to nearby lymph nodes or distant body parts.

In the case of Stage I to II anal cancer, chemotherapy along with radiotherapy is considered the preferred treatment.

Stage III (Any T N0-1 M0)

Stage IIIA (T1-2 N1 M0)

The primary tumor is </=5 cm in size and it has spread to nearby lymph node(s). No spread to distant body parts.

Stage IIIB (T4 N0 M0)

The primary tumor of any size that has invaded in a nearby organ, such as the vagina, prostate gland, urethra, or bladder. No spread to nearby lymph nodes or distant body parts.

Stage IIIC (T3-4 N1 M0)

The primary tumor is >5 cm in size or it has invaded in a nearby organ and it has spread to nearby lymph node(s). No spread to distant body parts.

In the case of Stage III anal cancer, chemotherapy along with radiotherapy is considered the first-line treatment.

Stage IV (Any T Any N M1)

The primary tumor has spread to the distant site(s), such as the lung, liver, peritoneum, etc.

In the case of Stage IV anal cancer, chemotherapy is the mainstay of treatment.

Surgery for Anal Cancer

surgery for anal cancer

Surgery is the first choice of treatment for early-stage anal cancer. Precancerous lesions or lesions that are present only in the superficial layer can be treated by local resection. In abdominoperineal resection (APR), the anus and rectum are surgically removed along with regional lymph nodes. An artificial opening (stoma) is created in the abdomen to collect stools in a bag attached to it.

Radiation Therapy

radiation therapy

Radiotherapy (along with chemotherapy) is commonly used as first-line treatment of many cases of anal cancer. It is also sometimes used for palliation of symptoms of the advanced-stage disease such as pain, bleeding, obstruction, etc.

Chemotherapy

role of chemotherapy

Chemotherapy (in conjunction with radiotherapy) is considered the first-line treatment for most locoregionally advanced anal cancers. Also, chemotherapy is the mainstay of treatment for the advanced-stage disease that has spread to distant body parts.

Chemotherapy drugs that are a part of anal cancer treatment regimens are-

5 Fluorouracil

Mitomycin

Paclitaxel

Carboplatin

Capecitabine

Cisplatin

Immunotherapy

role of immunotherapy

Nivolumab and pembrolizumab target the PD-1 protein on T-cells and activate them to kill cancerous cells. The immunotherapy is generally used for the treatment of advanced-stage disease unresponsive to primary treatment.

These are the various treatment options for anal cancer that may help in improving survival. Read anal cancer survivor story to gain more insight.

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