TAMIS

TAMIS is the abbreviation of “Transanal Minimally Invasive Surgery”. In plain terms it is transanal minimally invasive surgery, that is, “keyhole surgery performed through the back passage”.

In this method, without any incision in the abdomen, a special working port is placed into the rectum through the back passage. Using fine surgical instruments working under camera vision, a suitable polyp or tumour in the rectum is removed.

The basic aim of TAMIS, in suitable patients, is to remove the lesion:

• In one piece,
• With safe surgical margins,
• Where necessary, including all layers of the rectal wall,
• While preserving the surrounding healthy tissue as far as possible [1–4].

Not making an incision in the abdomen may make it possible to treat only the diseased area, without the need to remove the whole rectum. However, TAMIS is not suitable for every rectal polyp or rectal cancer. The most important conditions for success are correct patient selection, detailed staging and an experienced surgical team.

TAMIS is mostly considered for lesions located in the rectum that cannot be removed safely or completely with standard colonoscopic methods.

Large and difficult-to-reach rectal polyps

Most polyps in the rectum can be removed during colonoscopy. However, some polyps may be more suitable for removal with TAMIS if they:

• Are large,
• Have a broad base,
• Are located in a difficult area,
• Have previously undergone an attempt at removal, leaving scar tissue beneath them,
• Cannot be reliably assessed by pathology if removed in pieces,
• Raise suspicion of deep extension or cancer.

TAMIS is an important option particularly when the lesion needs to be removed in one piece and its surgical margins need to be assessed in detail by the pathologist [2–4].

Selected early-stage rectal cancers

TAMIS can be used for treatment only in carefully selected early-stage rectal cancers.

Local excision may generally be considered for clinical T1N0 rectal cancers that are:

• Thought to be confined to the superficial layers of the rectal wall,
• Without suspicious lymph nodes in the surrounding area,
• Small, mobile and suitably located,
• Showing low-risk features on imaging and biopsy findings [1,5].

However, pre-operative tests cannot always show the true depth of the tumour with certainty. If the detailed pathological examination after TAMIS finds a more advanced cancer than expected or high-risk features, a completion radical rectal operation or other treatments may be needed.

Rectal neuroendocrine tumours

Some neuroendocrine tumours found in the rectum may not be completely removable endoscopically. When the tumour’s size, depth and cellular features and the result of the previous procedure are suitable, a completion full-thickness excision can be performed with TAMIS.

Other selected rectal lesions

In experienced centres, when patient and lesion features are suitable, TAMIS may also be considered in the following situations:

• Suspicious tissue remaining at the site of a previously removed polyp
• Some benign tumours of the rectum
• Combining diagnosis and treatment in selected early-stage lesions
• Rectal lesions that are difficult to reach with standard methods
• Some special transanal surgical procedures

Not all of these uses have the same level of scientific evidence. The decision should be made individually according to the type of disease, the imaging findings and the surgeon’s experience.

The decision on TAMIS is not made by looking only at the size of the lesion. The following features are assessed together:

• The distance of the lesion from the anus
• Its location on the front, back or side wall of the rectum
• The size of the lesion and how much of the circumference of the rectum it covers
• Whether it is mobile or fixed
• Surface appearance and suspicion of deep spread
• The biopsy result
• Rectal MRI or endorectal ultrasound findings
• Whether there are suspicious lymph nodes in the surrounding area
• Whether a previous attempt at endoscopic removal has been made
• The patient’s general health
• Existing control of wind and stool

When TAMIS is planned for the treatment of cancer, patient selection is much stricter. In current guidelines, local excision is an option accepted mainly for low-risk, clinical T1N0 rectal cancers [1,5].

Who may TAMIS not be suitable for?

In the following situations, TAMIS alone may not be a sufficient cancer treatment:

• The tumour having advanced deeper into the rectal wall
• Suspicious lymph nodes being seen on MRI or endorectal ultrasound
• The tumour being fixed
• Spread to distant organs
• Poor cellular differentiation
• Tumour spread into lymphatic or blood vessels
• Tumour cells being present around nerves
• Marked tumour budding
• Deep submucosal involvement
• Tumour being present at the excision margin
• The lesion being too extensive to be removed safely in one piece

Some of these features can only be identified by the pathological examination carried out after TAMIS. For this reason, it should be discussed openly with the patient before the procedure that a second operation may be needed depending on the pathology result.

Before TAMIS, the aim is to determine the structure and depth of the lesion as accurately as possible.

The assessment may include:

• Colonoscopy and biopsy
• Digital rectal examination
• Rectoscopy or proctoscopy
• High-quality rectal MRI
• Endorectal ultrasonography
• Blood tests
• CT of the chest and abdomen if there is a cancer diagnosis
• Tumour markers in patients who need them
• Anaesthesia assessment

The distance of the lesion from the anus, its orientation on the rectal wall and the area it covers are recorded in detail before the procedure.

Is the biopsy result sufficient?

A biopsy takes a sample from only a small part of the lesion. While benign tissue is seen in one part of a large polyp, early cancer may be present in another part. For this reason, a benign biopsy result does not mean with certainty that there is no cancer anywhere in the lesion.

Removing the lesion in one piece with TAMIS helps the pathologist to assess more reliably:

• The true depth of the tumour,
• The excision margins,
• Spread into lymphatic and blood vessels,
• The cellular grade,
• Other risk features.

The procedure is mostly performed under general anaesthesia. Before the operation, bowel preparation and antibiotic preparation may be given as recommended by the doctor.

During the operation:

1. The patient is placed in a position suited to the location of the lesion.
2. A special working port is placed into the rectum through the anal canal.
3. Carbon dioxide gas is introduced in a controlled way to create a working space inside the rectum.
4. With the help of a camera, the lesion is viewed magnified and in detail.
5. The lesion is removed while maintaining the necessary safe margins.
6. In suitable cases, the opening in the rectal wall is closed with stitches.
7. The removed tissue is oriented and sent for pathological examination.

Depending on the features of the lesion, only the superficial layers or the full thickness of the rectal wall may be removed. For lesions where cancer is suspected, the aim is removal in one piece, without fragmentation.

TAMIS can be performed with standard laparoscopic instruments or, in suitable centres, with robotic systems. Regardless of the platform used, the most important points are correct patient selection, a safe surgical margin and good-quality pathological assessment [2–4].

In suitable patients, the main advantages TAMIS can offer are:

• No surgical incision in the abdomen
• Preservation of the rectum and of bowel continuity
• No stoma needed in most patients
• Precise removal of the lesion under a magnified view
• Access to lesions higher up than with standard direct transanal surgery
• Removal of the lesion in one piece
• More reliable assessment of the pathological margins
• Post-operative pain usually being limited
• A generally short hospital stay
• An earlier return to daily life
• Better preservation of bowel, urinary and sexual function compared with major abdominal operations

A systematic review and meta-analysis published in 2024 reported that TAMIS and rigid transanal platforms gave similar results in terms of surgical margins and the quality of the removed specimen, and that overall short-term complication and readmission rates were lower in the TAMIS group [2].

Nevertheless, results may vary according to the features of the lesion, the surgeon’s experience and the centre’s patient selection. The advantages of TAMIS apply only to patients for whom the method is suitable.

TAMIS is a minimally invasive method, but it is not entirely risk-free. Possible problems include:

• Bleeding after the operation
• Infection
• Temporary difficulty passing urine
• Pain or discomfort when opening the bowels
• Breakdown of the suture line in the rectal wall
• Unintended entry into the abdominal cavity
• Narrowing of the rectum
• Development of an abnormal connection between the rectum and surrounding organs
• Temporary changes in control of wind or stool
• Incomplete removal of the lesion
• Recurrence of the disease at the same site
• A need for an additional endoscopic procedure or operation may arise.

Serious complications are uncommon; however, the size and location of the lesion and the extent of rectal wall removed may affect the risk.

What is the most important limitation of TAMIS?

TAMIS removes only the lesion in the rectal wall; it does not remove the lymph nodes around the rectum.

Even in a rectal cancer that appears early, microscopic spread to the lymph nodes may be present. For this reason, TAMIS is not equivalent to standard radical rectal surgery for cancers with a high risk of lymph node spread [1,5].

If one of the following features is found on pathology after TAMIS, completion treatment may be recommended:

• The tumour being deeper than expected
• Tumour being present at the surgical margin
• Poor differentiation
• Spread into lymphatic or blood vessels
• Spread around nerves
• High-grade tumour budding
• Deep submucosal invasion
• Fragmented removal, or removal with inadequate pathological assessment

In this case, radical rectal surgery including total mesorectal excision or, in selected patients, other oncological treatments are considered.

Important: A recommendation for further surgery after TAMIS does not mean that the procedure has failed. When detailed examination of the removed tissue reveals previously unknown risk features, cancer treatment may need to be completed safely.

How long will I stay in hospital?

The hospital stay varies according to the extent of the procedure and the patient’s general condition. Many patients can be discharged on the same day or the following day. After more extensive full-thickness excisions or in situations requiring close monitoring, the stay may be longer.

What may happen after the operation?

In the first days, the following may occur:

• Mild pain or a feeling of fullness in the back passage
• A small amount of bloody or mucous discharge
• Tenderness when opening the bowels
• A temporary change in bowel habits
• A short-term difference in wind control.

These symptoms mostly lessen over time. The painkillers recommended by the doctor, drinking enough fluids and keeping the stool soft make recovery easier.

When can I return to daily life?

Light daily activities can usually be started within a few days. In many patients, a return to desk work may be possible within about a week. The extent of the procedure and the physical demands of the job affect this period.

For heavy lifting, intensive exercise and long journeys, the period recommended by the surgeon should be observed.

With which symptoms should I contact the healthcare team?

In the following situations, the healthcare team should be contacted without delay:

• Heavy or persistent bleeding from the back passage
• Increasing abdominal or anal pain
• Fever and shivering
• Marked swelling of the abdomen
• Persistent nausea or vomiting
• Inability to pass wind or stool
• Inability to pass urine
• Foul-smelling or purulent discharge
• A new, serious problem with control of wind or stool

Why is the pathology result important?

Whether TAMIS is the definitive treatment becomes certain after the pathological examination of the removed tissue.

The pathology result assesses:

• Whether the lesion is benign or malignant,
• If there is cancer, the depth of its progression into the wall,
• Whether it has been completely removed,
• Its cellular features,
• Lymphatic and vascular involvement,
• Risk findings requiring further treatment.

If the result is a benign or low-risk lesion removed with safe margins, regular follow-up may be sufficient. With high-risk features, completion surgery or oncological treatment may be considered.

How is follow-up carried out?

The follow-up programme is determined individually according to the pathology result. At check-ups, the following may be used:

• Examination
• Rectoscopy or colonoscopy
• Rectal MRI
• Endorectal ultrasonography
• Blood and imaging tests required in the case of a cancer diagnosis.

In patients who have had TAMIS for cancer, follow-up is more frequent and longer than in patients who have had a benign polyp removed. Not missing check-ups is important for the early detection of a problem that may develop at the same site.

Finding a polyp or an early-stage tumour in the rectum does not necessarily mean that a major abdominal operation will be performed. When the location, size and biopsy result of the lesion and its depth in the rectal wall are suitable, TAMIS may be a treatment option.

To assess suitability for TAMIS, the existing:

• Colonoscopy report,
• Pathology result,
• Endoscopy images,
• Rectal MRI,
• Documents relating to previous treatments should be reviewed together.

1. Hofheinz RD, Fokas E, Benhaim L, et al. Localised Rectal Cancer: ESMO Clinical Practice Guideline for Diagnosis, Treatment and Follow-up. Ann Oncol. 2025;36(9):1007–1024. doi:10.1016/j.annonc.2025.05.528.
2. Garoufalia Z, Rogers P, Meknarit S, et al. Trans-anal Minimally Invasive Surgery Versus Rigid Platforms for Local Excision of Early Rectal Cancer: A Systematic Review and Meta-analysis. Surg Endosc. 2024;38:4198–4206. doi:10.1007/s00464-024-11065-6.
3. Piozzi GN, et al. Robotic Transanal Minimally Invasive Surgery for Rectal Neoplasms: A Systematic Review of Outcomes and Innovations. Langenbecks Arch Surg. 2026;411. doi:10.1007/s00423-025-03904-4.
4. Devane LA, Burke JP, Kelly JJ, Albert MR. Transanal Minimally Invasive Surgery for Rectal Cancer. Ann Gastroenterol Surg. 2021;5(1):39–45. doi:10.1002/ags3.12402.
5. You YN, Hardiman KM, Bafford A, et al. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Rectal Cancer. Dis Colon Rectum. 2020;63(9):1191–1222. doi:10.1097/DCR.0000000000001762.