Rectal Cancer: Advances in Anus-Preserving Surgery - Medical Frontiers

Key Concepts

• Rectal Cancer
• Stoma (Colostomy/Ileostomy)
• Sphincter-Preserving Surgery
• Laparoscopic Surgery
• Robotic Surgery
• Total Mesorectal Excision (TME)
• Pelvic Floor Muscles
• Artificial Intelligence (AI) in Surgery

Rectal Cancer: A Growing Global Concern

An international medical journal reported in 2025 that rectal cancer has become a global issue. Previously more common in individuals over 50, it is now increasingly affecting younger generations. By 2030, it is projected that 10% of cases will be in individuals under 40. The large intestine processes digested food into feces, which are temporarily stored in the rectum, a 15-20 cm section connected to the anus. The anus controls the release of feces.

Traditional Treatment and its Challenges

Historically, the standard treatment for rectal cancer, especially when it involves the anus, was to remove most of the rectum and, in some cases, the anus. This often necessitated the creation of a stoma, an opening in the abdomen, to allow for waste expulsion into a bag attached to the body. According to the World Health Organization, approximately 700,000 new cases of colorectal cancer are diagnosed annually.

The creation of a stoma significantly impacts a patient's quality of life (QOL). Individuals with stomas do not have the sensation of a bowel movement and must manage their waste regularly. This can be an emotional burden and lower their self-esteem. A survey of about 4,000 patients by a stoma support group revealed that many worried about managing their stoma, including concerns about skin irritation, odor, leakage, and difficulties in daily life.

Advancements in Surgical Technology

Cutting-edge innovations in surgical technology, powered by robotic assistance and artificial intelligence, are offering new hope. These breakthroughs are making it possible to treat cancer while preserving natural function and avoiding stomas in more cases.

Sphincter-Preserving Surgery

Rectal cancers are classified into five stages based on their progression. If detected early, the cancerous area can sometimes be removed using endoscopic treatment. However, if the cancer is more advanced or located near the anus, surgical intervention is often required.

When the anus is removed, a stoma must be created. However, if the cancer is located away from the anus, doctors can remove the rectum while preserving the anus. But if the cancer is in the lower rectum, near the anus, the anus is sometimes removed.

Dr. Eto, who has performed over 2,000 rectal cancer surgeries and specializes in sphincter-preserving procedures, highlights the shift in treatment philosophy. He notes that over 20 years ago, rectal cancer often resulted in a permanent stoma, significantly impacting QOL. Many patients expressed a strong desire to retain their anus. Dr. Eto states, "As a doctor, I want to preserve the patient's anus if I can."

The Role of Key Muscles

Two muscles play a key role in surgeries aimed at preserving the anus:

• Inner Muscle: This muscle automatically contracts and relaxes in sync with rectal movements.
• Outer Muscle: This muscle can be controlled voluntarily to tighten and loosen the anus.

In surgeries for rectal cancer located near the anus, only the inner muscle is removed along with the cancer. The rectum is then connected to the outer muscle. Preserving this voluntary outer muscle allows for normal anal function.

Laparoscopic Surgery

Traditionally, rectal cancer surgeries were performed with large incisions. Since the 1990s, laparoscopic surgery has enabled more precise procedures. This technique involves inserting a camera and instruments through small incisions, allowing surgeons to operate while viewing magnified images on a screen. Compared to open surgery, laparoscopic surgery results in less bleeding and pain, carries a lower risk of postoperative complications, and leads to shorter hospital stays.

Studies show significant success rates for laparoscopic sphincter-preserving surgery. In one report, only 6.3% of cases required a stoma after laparoscopic sphincter-preserving surgery. After five years, 87% of patients were still able to use their own anus.

Challenges and Innovations in Laparoscopic Surgery

However, laparoscopic surgery for rectal cancer presents challenges. A wide area around the tumor, including lymph nodes, must be removed to prevent cancer spread. The rectum is located near the bladder and nerves related to reproductive function. Approaching from the abdominal side can obstruct access to the tumor and lymph nodes.

Dr. Eto's team addresses this with a procedure known as Total Mesorectal Excision (TME). This involves two surgeons operating simultaneously: one from the abdomen and the other from the anus. One surgeon uses a laparoscope from the abdominal side to remove lymph nodes and the anal muscle, while the other surgeon works from the anal side. The two approaches meet, and the rectum is connected to the outer muscle. This dual-approach TME is approved for safety and shortens operation time.

The TME procedure requires new knowledge and techniques, particularly regarding nerve preservation for urinary and sexual functions. The AI-assisted navigation system helps surgeons visualize and preserve these critical autonomic nerves.

Efficiency and Training in TME

The dual-approach TME surgery significantly reduces operation time. While traditional rectal cancer surgeries can take around 5.5 hours, Dr. Eto's team completes them in about half that time. This leads to shorter anesthesia and surgery durations, resulting in faster patient recovery.

However, the technique is complex and requires extensive training for surgeons. Dr. Eto notes, "The challenge is that there are few mentors who can teach it." This training gap is a significant hurdle.

Robotic Surgery

Robotic surgery is increasingly being adopted. Robotic systems are expensive and require specialized operating rooms. Dr. Eto's team developed a laparoscopic design specifically for TME surgery. The robot has three arms: one for the endoscope and two for instruments. These arms move in coordination with the surgeon's hand movements.

The development of this robotic system began in 2015, focusing on essential functions. In 2022, it was approved as a medical device in Japan. Dr. Eto believes that as robotic technology advances and prices decrease, more hospitals will be able to adopt these procedures.

AI-Powered Navigation System

Dr. Eto's team is also developing an AI-powered navigation system for laparoscopic surgeries. These surgeries are difficult without extensive surgeon experience. The AI system is trained to highlight critical structures like nerves and the ureter in real-time on the surgical display.

The AI system helps surgeons perform operations with greater safety by identifying structures that can be difficult to discern even for experienced surgeons. The engineers are manually feeding the AI data on nerves and ureters from approximately 100 surgeries.

Dr. Eto's ultimate goal is to automate necessary functions to make surgery safer, not to automate dangerous aspects. He believes the combination of robotics and AI is crucial for achieving partial automation and providing safer surgical outcomes.

Pelvic Floor Muscles and Core Strength

The pelvic floor muscles play a crucial role in urination and defecation. When they weaken, it can lead to urinary leakage. Strengthening these muscles can prevent such issues.

Pelvic Floor Exercises

Exercises to strengthen the pelvic floor muscles involve consciously tightening and relaxing them. It's important to feel the movement of the pelvic bones during these exercises. Maintaining good posture and avoiding tension in the abdomen are also key.

• Exercise: Lie down and practice contracting and relaxing the pelvic floor muscles, imagining holding back urination.
• Side-lying exercise: This can also be effective for activating pelvic floor muscles.
• Back stretching: Stretching the back, particularly the spine, also engages the pelvic floor muscles and core. This involves getting on all fours and arching the back like a cat, then stretching the spine. Stretching the hip flexors is also beneficial.

Dr. Tanaka emphasizes the importance of feeling the movement of the tailbone during these exercises to ensure correct execution.

Conclusion

As Japan's population ages, cancer is affecting more lives. Modern medical care must not only save lives but also preserve quality of life. Staying informed about the latest surgical advancements and making informed treatment choices is therefore more important than ever.