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Current medical literature supports transanal minimally invasive surgery (TAMIS), a form of local excision, for benign lesions and some early stage cancers of the rectum (Tis, T1). In early cancers, the cancer cells are most likely contained within the tumor and have not yet spread. TAMIS may also be performed for some more advanced cancers, such as T2. TAMIS is rarely performed for advanced tumors (T3, T4) when the cancer is likely to have spread outside the primary tumor site. TAMIS can only offer palliative treatment for T3 and T4 tumors in the event that a patient declines, or is not healthy enough, to undergo traditional open or laparoscopic surgery. Your doctor will consider several factors to determine whether you are a candidate for a TAMIS procedure. Eligibility depends on tumor size and type, location of tumor within the rectum, and surgeon experience.

Clinical literature has shown TAMIS to be effective for benign lesions and some early cancers in the rectum. TAMIS is less commonly performed for advanced cancers where the chance of recurrence or metastasis is higher. While TAMIS offers benefits for early cancers, typically traditional surgery is more effective for advanced tumors. Consult with your physician to determine which procedure is best to treat your individual condition.


Following a colonoscopy and diagnosis of a rectal tumor, additional tests may be performed to determine the stage and type of the tumor. Most rectal polyps are initially classified as benign, meaning they do not contain cancer. However, if left untreated, a benign polyp may develop into cancer and can potentially spread within the body. Cancer can spread by growing into surrounding normal tissue, traveling through the lymphatic system, and/or traveling through the blood. As cancer cells break away from their source, a secondary tumor may form. This process is called metastasis.

  • Rectal Cancer Staging Diagram of Benign and Malignant Stages for TAMIS Surgery
  • Rectal Cancer Staging Diagram Layers of the Bowel Wall for TAMIS Surgery

TAMIS is commonly performed for:

  • Benign Polyps — It is fairly common for an abnormal growth of tissue, called a polyp, to form on the mucous membrane of the bowel wall. Initially most are classified as benign with no risk of malignancy. If a benign tumor continues to grow unattended, it can develop into cancer.
  • Classification of Benign Polyps:
  • Adenomatous polyps, or adenomas, are non-cancerous growths that are considered precursors to colorectal cancer.
  • Hyperplastic polyps are growths which have little to no potential for malignancy.
  • Tis — Cancer in its earliest stage is called carcinoma in situ. The abnormal cells are contained within the innermost layer of the rectum, called the mucosa. The cancer cells have not yet grown into the submucosa.
  • T1 — Cancer has grown through the mucosa and into the submucosa, the fibrous layer beneath the mucosa. The cancer has not yet grown into the muscularis propria, the thick muscle layer of the rectum.

TAMIS is sometimes performed for:

  • T2 — Cancer has grown through the submucosa and into the thick muscle layer of the rectum, the muscularis propria. Cancer cells have not grown into the serosa.

TAMIS is NOT commonly performed for:

  • T3 — Cancer has spread through the muscularis propria and into the outermost layer of the rectum, called the serosa. The cancer has not penetrated through the serosa or spread to nearby organs or tissues.
  • T4A — Cancer has spread through the serosa.
  • T4B — Cancer has grown through the rectal wall and into nearby organs.


Early stages of rectal cancer typically do not cause symptoms. Symptoms often become noticeable and may increase in severity with more advanced stages of cancer. It is important to consult with your doctor if you experience one or more of the following symptoms:

  • Fatigue
  • Change in appetite
  • Unintended weight loss
  • Lower back and stomach pain
  • Blood in stool
  • Narrow stools
  • Constipation
  • Gas pains or bloating
  • Painful bowel movements
  • Bowel not emptying completely
  • Diarrhea
  • Dehydration

Note: Most often these symptoms are not caused by rectal cancer and may indicate a less serious medical condition. It’s important to consult with your doctor so that you can receive a diagnosis and proper treatment for your condition.


Only a trained surgeon can determine whether you are eligible for a TAMIS procedure. All minimally invasive surgical procedures present potential risk to the patient, including conversion to a traditional open procedure. These specific risks may only be evaluated in consultation with a surgeon experienced with TAMIS. While clinical literature has supported TAMIS, individual results may vary. Consult with your physician to determine the best treatment option for your diagnosis.