When rectal cancer returns after initial treatment, it is called locally recurrent rectal cancer (LRRC). Despite major improvements in surgery and pre-operative therapy, rectal cancer comes back locally in roughly 6% to 10% of patients even with modern techniques like total mesorectal excision.
The outlook for patients with LRRC who receive only chemotherapy or radiation without surgery is very poor, with a median survival of less than 8 months. Complete surgical removal remains the only treatment that offers a realistic chance of cure and long-term survival.
One special challenge with LRRC is that the returning tumor often grows in an infiltrative pattern and is surrounded by dense scar tissue. This makes it difficult to see clear boundaries during surgery and means that surgeons frequently need to remove the cancer together with nearby structures such as the sacrum (the triangular bone at the base of the spine).
Removing the sacrum as part of this surgery, called sacrectomy, has traditionally been associated with heavy intraoperative bleeding and serious post-operative infections. This paper describes a new, minimally invasive approach developed at Osaka University to address these problems.
Sacrectomy means surgically removing all or part of the sacrum when a rectal tumor has grown into or behind it. Conventional open sacrectomy is a very large operation that carries high risks of massive blood loss and pelvic infections after surgery.
The surgeons at Osaka University developed a laparoscopic (keyhole) approach to perform the first and most complex parts of the operation through small incisions using a camera and specialized instruments. This reduces trauma to the body compared to a fully open procedure.
In this technique, the front and sides of the sacrum are carefully prepared using the laparoscope while the patient lies on their back. The final cutting of the sacral bone is then completed under direct vision when the patient is repositioned face-down. This two-step approach gives surgeons precise control and minimizes the chance of unexpected bleeding.
The team also developed a companion technique called dead-space-filling nonfunctional (DFN) anastomosis, a way to use a loop of bowel to fill the large cavity left behind after the sacrum is removed. This helps prevent the dangerous pelvic infections that often complicate traditional sacrectomy.
Before surgery, the team uses MRI imaging to carefully map where the tumor sits in relation to the sacrum and to identify exactly where the sacral bone will need to be cut. This measurement is translated into a physical guide during the operation.
A key technical innovation involves using a premeasured nonelastic surgical tape during the laparoscopic portion. Since surgeons cannot see the sacral bone directly through the camera, this tape acts as a ruler to reliably locate the planned cutting line relative to known anatomical landmarks such as blood vessel junctions.
The surgeons also perform lateral lymph node dissection during this phase. Beyond its cancer-clearing purpose, this step helps clearly map out the course of the internal iliac blood vessels, which are then divided in advance. Controlling these vessels early is critical to preventing massive bleeding when the sacral bone is eventually cut.
The upper limit for safe sacral removal is set at the lower edge of the second sacral vertebra (S2). Going higher risks damage to the lumbosacral trunk or the S1 nerve root, which could result in foot drop or severe walking difficulties after surgery.
With the patient lying on their back, surgeons use five laparoscopic ports (small incisions) to enter the pelvis with a camera and instruments. The tissue covering the front surface of the sacrum is carefully cut away to expose the underlying bone, reducing the risk of bleeding from the median sacral vein by applying soft electro-coagulation before each cut.
The dissection is extended sideways along both sides of the sacrum with the aim of reaching the sacrospinous ligaments from the front. This proactive approach allows the surgical team to address bleeding-prone vessels on the sides of the sacrum before the bone itself is cut, greatly reducing the chance of dangerous bleeding during the final stage.
If any part of the patient's previously reconstructed bowel sits within the pelvis near the planned cutting line, it is divided first to create space and give a clear view of the operative field. This meticulous preparation during the laparoscopic phase is what makes the final bone-cutting step safer and more controlled.
Throughout this phase, the team uses an ultrasonic coagulating and cutting device for precise tissue work and a saline-irrigated electrode for pre-coagulation of blood vessel-rich areas. Together, these tools help keep blood loss at a minimum during the most delicate part of the dissection.
After the laparoscopic preparation is complete, the patient is repositioned face-down (the prone position) for the final stage. A skin incision is made along the back of the pelvis, and the surface of the sacrum is exposed. Because the front and sides of the sacrum were already freed during the laparoscopic phase, the surgeon can easily feel the planned cutting line from the back.
The sacral bone is divided using a chisel (osteotome) and mallet along the confirmed line. The combination of prior laparoscopic preparation and direct visual guidance makes this final step precise and greatly reduces the risk of injuring nerves or causing major bleeding.
When possible, the anus is preserved even though it will no longer function for waste elimination. Prior work by this team showed that keeping the anus in place helps prevent severe pelvic abscess formation after surgery, so preservation is attempted whenever the cancer margins allow it.
Once the specimen is removed, the large cavity left behind (called dead space) must be filled to prevent infection. An omental flap, a piece of fatty tissue from the abdomen with its own blood supply, is moved into the pelvis to cover the raw bone surface and act as a protective biological barrier.
Even after placing an omental flap, the large empty space in the pelvis after sacral removal can still harbor bacteria and lead to dangerous infections. The team developed a second reconstruction technique: the dead-space-filling nonfunctional (DFN) anastomosis.
In this technique, the descending colon is re-mobilized and connected to the remaining rectal stump or anal canal. This creates a loop of bowel that physically fills the deepest part of the pelvic cavity. Although this bowel segment does not carry stool (the patient uses a stoma for that function), its presence displaces the empty space and greatly reduces the risk of infection taking hold there.
The omental flap is always placed behind the reconstructed bowel, sitting directly on the raw bone surface. This layered arrangement provides a well-vascularized barrier between the bone and the bowel and is expected to reduce both infection risk and the chance of bowel injury from contact with the rough bony surface.
All patients have a double-barreled stoma created higher up in the colon so that stool is diverted away from the reconstruction. The double-barreled design is chosen because it also allows safe endoscopic monitoring of the reconstructed bowel segment after surgery, even though no cancer has been seen to arise in that segment.
Between 2014 and 2024, the Osaka University team performed this laparoscopic sacrectomy technique in 43 patients with locally recurrent rectal cancer. The results were encouraging for such a technically difficult patient population.
The R0 resection rate, meaning the cancer was removed with clear margins (no cancer cells at the edges), was 83% (37 out of 43 patients). Achieving clear margins is one of the most important factors for long-term survival in recurrent rectal cancer surgery.
In a detailed case example described in the paper, the operative time was 762 minutes (approximately 12.7 hours) and estimated blood loss was just 182 mL, which is remarkably low for a procedure of this scale and allowed the surgery to be completed without a blood transfusion.
Early follow-up data suggest a 5-year overall survival rate of approximately 59%. This compares favorably to the 35.3% five-year survival rate reported by the large international PelvEx Collaborative for similar patients, though direct comparison is limited by differences in patient selection and surgical methods.
For patients whose rectal cancer has returned near the sacrum, this technique offers a potential path to curative surgery with a lower risk profile than traditional open operations. The minimally invasive approach reduces both intraoperative blood loss and the chance of post-operative sepsis.
It is important to understand that this is a highly specialized procedure performed at an experienced cancer center. Not every patient with LRRC will be a candidate for this approach. Suitability depends on the exact location and extent of recurrence, the patient's overall health, and prior treatments received.
The surgical team emphasizes careful pre-operative planning with MRI imaging as a cornerstone of success. Understanding exactly where and how to cut before entering the operating room translates directly into safer intraoperative decision-making.
Patients undergoing sacral resection should understand that normal bowel function cannot be preserved after this type of surgery. A permanent stoma is required. Preserving the anus where surgically possible, however, has been shown to reduce the risk of pelvic abscess and is still attempted when margins allow it.
This paper demonstrates that laparoscopic sacrectomy combined with dead-space-filling reconstruction is a safe and technically feasible approach for selected patients with posterior locally recurrent rectal cancer. The technique achieves high rates of clear margins while keeping blood loss and complication rates acceptably low.
The 5-year survival rate of approximately 59% in this series is notably better than historical comparisons and suggests that an aggressive but precise minimally invasive surgical strategy can meaningfully improve outcomes in this difficult-to-treat patient group.
The authors acknowledge that larger prospective studies comparing this technique to conventional approaches are needed before definitive conclusions can be drawn. Differences in patient selection between centers make direct comparisons challenging at this stage.
Future research should focus on further refining patient selection criteria, optimizing the reconstruction approach, and reporting longer-term oncological outcomes to confirm whether the promising early results are sustained over time. This work represents an important step forward for minimally invasive surgery in rectal cancer recurrence.