Rectal Cancer Treatment And Surgery Specialist In Bozeman, Montana

What is rectal cancer?

Rectal cancer develops when abnormal cells grow uncontrollably within the rectum, the final portion of the large intestine immediately above the anus.

Although colon and rectal cancers arise from similar tissues, rectal cancer requires a distinct treatment strategy because the rectum lies deep within the pelvis near the anal sphincters, bladder, prostate, vagina, pelvic nerves, and other important structures.

Treatment must address both removal or eradication of the cancer and preservation of bowel, urinary, and sexual function whenever possible.

What symptoms can rectal cancer cause?

Early rectal cancer may cause no symptoms. When symptoms occur, they may include rectal bleeding, a persistent change in bowel habits, urgency, incomplete evacuation, narrow stools, rectal pressure, anemia, weight loss, fatigue, or abdominal pain. Persistent bleeding or changes in bowel function require evaluation.

How is rectal cancer diagnosed and staged?

Most rectal cancers are identified during colonoscopy, which allows the gastroenterologist to examine the tumor and obtain a biopsy.

Once cancer is confirmed, staging generally includes blood testing, measurement of carcinoembryonic antigen, or CEA, CT imaging of the chest, abdomen, and pelvis, and a dedicated rectal MRI. The MRI defines the tumor’s position, depth, relationship to the anal sphincters and surrounding structures, lymph-node involvement, and other features that influence treatment.

The tumor is also tested for molecular characteristics, including mismatch-repair deficiency and microsatellite instability, because these findings may substantially change treatment.

Why is multidisciplinary treatment important?

Rectal cancer treatment often involves several forms of therapy delivered in a carefully planned sequence.

Dr. Zehnpfennig works with medical oncology, radiation oncology, radiology, pathology, and gastroenterology to review the staging information, determine whether treatment should begin with chemotherapy or radiation, evaluate the response, and help you decide whether the best next step is surgery, local excision, or nonoperative surveillance.

The plan depends on the tumor’s stage, location, molecular profile, response to treatment, and your priorities.

What is total neoadjuvant therapy?

Total neoadjuvant therapy, commonly called TNT, delivers the planned chemotherapy and radiation before rectal cancer surgery.

Traditional treatment often placed some chemotherapy after surgery, when patients were still recovering and might not complete all recommended treatment. TNT allows systemic therapy to begin earlier, improves treatment completion, treats microscopic disease throughout the body, and increases the chance that the rectal tumor will shrink substantially or disappear before surgery.¹˒²

TNT may include chemotherapy followed by chemoradiation, chemoradiation followed by consolidation chemotherapy, or another sequence selected by the multidisciplinary cancer team.

Can rectal cancer disappear without surgery?

Some rectal cancers have a complete clinical response after chemotherapy and radiation. This means no residual tumor can be detected by digital examination, endoscopy, or rectal MRI.

For appropriately selected patients, a complete clinical response may allow a watch-and-wait strategy instead of immediate rectal resection. This is now an accepted organ-preservation approach when it is provided by an experienced multidisciplinary team with intensive surveillance.

In the OPRA trial, approximately half of patients treated with one TNT sequence remained free from total mesorectal excision at five years.² Most local tumor regrowth occurred during the first two years, when surveillance is most intensive.

What does watch-and-wait involve?

Watch-and-wait does not mean ignoring the cancer. It is an active surveillance program for selected patients who demonstrate a complete clinical response.

Follow-up includes frequent:

• Digital rectal examinations
• Flexible sigmoidoscopy or endoscopy
• Rectal MRI
• CEA blood testing
• CT imaging when appropriate

If tumor regrowth is detected, prompt surgery is usually recommended. Because local regrowth is most common during the first two years, strict adherence to follow-up is essential.

Patients who cannot or do not wish to comply with intensive surveillance are generally better served by definitive surgical treatment.

Can immunotherapy eliminate the need for surgery?

A small subset of rectal cancers have identifiable abnormalities in the systems that repair damaged DNA. These tumors are described as mismatch-repair deficient, or MMR-deficient, and microsatellite-instability high, or MSI-high. They can be exceptionally responsive to immune-checkpoint therapy.

Prospective studies of dostarlimab have shown complete clinical responses in patients with locally advanced mismatch-repair-deficient rectal cancer, allowing many to avoid chemotherapy, radiation, and surgery while continuing intensive surveillance.³ These results represent a major advance, although treatment selection and long-term follow-up require a specialized multidisciplinary team.

Every rectal cancer should undergo appropriate molecular testing because this information can fundamentally alter treatment.

When is surgery necessary?

Surgery remains essential when:

• The tumor does not completely respond to neoadjuvant treatment
• Residual cancer remains on examination, endoscopy, or MRI
• The tumor regrows during watch-and-wait surveillance
• Early-stage disease is best treated by local excision or resection
• Cancer causes bleeding, obstruction, perforation, or another urgent complication
• Organ-preservation treatment is not oncologically appropriate

The goal is complete cancer removal while preserving the anal sphincters and normal function whenever safely possible.

What is total mesorectal excision?

Total mesorectal excision, or TME, is the fundamental surgical technique used for most mid and low rectal cancers.

The rectum and the surrounding mesorectum—which contains the regional lymph nodes, blood vessels, and lymphatic tissue—are removed together within their natural anatomic envelope. Precise dissection along this plane reduces the risk of leaving cancer behind and protects nearby pelvic structures.

Dr. Zehnpfennig uses robotic surgery to perform TME with magnified three-dimensional visualization and wristed instruments designed for precise work within the confined pelvis.

What operations are performed for rectal cancer?

The operation depends on the tumor’s size, location, stage, response to treatment, and relationship to the sphincter muscles.

Transanal minimally invasive surgery

Transanal minimally invasive surgery, or TAMIS, allows selected early rectal tumors to be removed through the anus without an abdominal incision.

TAMIS may be appropriate for carefully selected early cancers. It is not a substitute for radical cancer surgery when the risk of lymph-node involvement is significant.

Low anterior resection

A low anterior resection removes the cancer-bearing rectum and reconnects the colon to the remaining rectum or anal canal.

This operation preserves the anus and allows bowel movements through the natural route. A temporary diverting ileostomy may be created to protect a very low bowel connection while it heals.

Abdominoperineal resection

An abdominoperineal resection removes the rectum, anus, and sphincter muscles and creates a permanent colostomy.

This operation is reserved for tumors that directly involve the sphincter complex or cannot be completely removed while preserving a functional anus. Modern staging, neoadjuvant treatment, and advanced pelvic surgery allow sphincter preservation in many patients who historically would have required a permanent colostomy.

Can rectal cancer surgery be performed robotically?

Most rectal cancer operations can be completed robotically.

The robotic platform provides stable, magnified three-dimensional visualization and articulated instruments that are particularly valuable during precise dissection deep within the narrow pelvis. This allows Dr. Zehnpfennig to perform total mesorectal excision, preserve pelvic nerves, divide the rectum at the appropriate level, and create a low bowel connection through small abdominal incisions.

When oncologically appropriate, the specimen may be removed through a natural opening. If natural-orifice extraction would jeopardize specimen integrity or cancer outcomes, Dr. Zehnpfennig completes the resection and reconstruction within the abdomen, then uses a limited abdominal extraction incision.

Will I need an ostomy?

Many patients with rectal cancer do not require a permanent ostomy.

A temporary ileostomy is sometimes used to protect a low colorectal or coloanal connection while it heals. The ileostomy is usually reversed during a later operation after the connection has been evaluated.

A permanent colostomy is generally necessary only when the cancer involves the anal sphincters, preserving the anus would compromise cancer removal, or the remaining sphincter would not provide acceptable function.

Dr. Zehnpfennig discusses the likelihood of a temporary or permanent ostomy before treatment whenever possible.

What is recovery like after rectal cancer surgery?

Recovery depends on the operation, previous chemotherapy and radiation, the height of the bowel connection, and whether an ileostomy is required.

Dr. Zehnpfennig follows an enhanced recovery pathway emphasizing robotic and minimally invasive surgery, multimodal pain control, early reintroduction of diet, and early ambulation.

Many patients meet discharge criteria within one or two days after uncomplicated minimally invasive surgery. Follow-up addresses pathology, ostomy care when applicable, bowel function, nutrition, urinary and sexual function, and the need for further cancer treatment or surveillance.

Why does specialist experience matter?

Rectal cancer surgery is among the most technically demanding areas of colorectal surgery. The surgeon must remove the cancer with an intact mesorectal envelope while protecting the sphincters, ureters, bladder, pelvic nerves, reproductive organs, and major blood vessels.

Dr. Zehnpfennig is a fellowship-trained colon and rectal surgeon with extensive experience in robotic pelvic surgery, total mesorectal excision, TAMIS, sphincter-preserving reconstruction, and enhanced recovery. He works with the multidisciplinary cancer team to pursue the strongest oncologic outcome while preserving the rectum, anus, and normal function whenever safely possible.

To arrange a rectal cancer consultation, call the office or request an appointment online.

1. Garcia-Aguilar J, et al. Organ preservation in patients with rectal adenocarcinoma treated with total neoadjuvant