[Long-Term Survival of a Patient with KRAS Mutated Colon Cancer Successfully Treated with Regorafenib].

A 65-year-old woman underwent iliocecal resection for cecal cancer. During post-operative follow-up, she was diagnosed with metastasis to the abdominal wall and a curative resection was performed. After 12 courses of adjuvant chemotherapy with a modified combination of folinic acid, 5-fluorouracil, and oxaliplatin (mFOLFOX6), recurrence was noted in the lung. A curative resection was successfully performed and she was subsequently treated with bevacizumab and a combination of folinic acid, 5-fluorouracil, and irinotecan (FOLFIRI). One year after surgical resection, recurrence in the remnant lung was diagnosed. Because of the KRAS mutation, she could not be treated with anti-epidermal growth factor antibodies. The metastatic lung tumor continued to enlarge. Therefore, we selected regorafenib as third-line chemotherapy. After treatment with regorafenib, the size of the target lesion decreased significantly.

Surgical treatment for kyphoscoliosis in Cohen syndrome.

Cohen syndrome is a very rare disease. Complication by spinal deformity has been reported, but management and surgery for spinal deformity in Cohen syndrome has not been previously described. The objective of this study was to examine the outcome of surgical treatment for kyphoscoliosis of Cohen syndrome with a literature review. The patient was a 14-year-old male with the characteristics of Cohen syndrome: truncal obesity, mental retardation, arachnodactyly, microcephalia, and a facial malformation. Scoliosis was conservatively treated with a brace at 13 years of age, but the spinal deformity rapidly progressed within a year. Plain radiographs before surgery showed scoliosis of 47 degrees (T5-T11) and 79 degrees (T11-L3), and kyphosis of 86 degrees (T7-L1). One-stage anteroposterior corrective fusion of T4-L3 was scheduled after 2-week Halo traction. Postoperative respiratory management was carefully performed because of Cohen syndrome-associated facial malformation, obesity, and reduced muscle tonus. Respiration was managed with intubation until the following day and no respiratory problems occurred. After surgery, thoracolumbar scoliosis was 28 degrees (correction rate: 65%). Kyphosis was markedly improved from 86 degrees to 20 degrees, achieving a favorable balance of the trunk. The outcome is favorable at 6.5 years after surgery. In conclusion, Cohen syndrome is often complicated by spinal deformity, particularly kyphosis, that is likely to progress even in adulthood. In our patient, spinal deformity progressed within a short period, even with brace treatment. Surgery should be required before progression to the severe spinal deformity with careful attention to general anesthesia.

Ventral hernia repair with enhanced-view totally extraperitoneal technique after a massive weight loss by laparoscopic sleeve gastrectomy.

BACKGROUND: Ventral hernia repair (VHR) for obese patients is often associated with an increased risk of postoperative complications and hernia recurrences. Achieving preoperative weight loss is ideal before VHR; however, it is difficult to attain with medical treatment. Metabolic and bariatric surgery (MBS) offers the most effective and durable treatment for obesity. Therefore, massive weight loss occurring after MBS will improve the outcome of VHR. CASE PRESENTATION: A 49-year-old man (122.9 kg, BMI 39.1 kg/m2) presented to our hospital wishing to undergo laparoscopic sleeve gastrectomy and VHR. Physical examination revealed a tennis ball-sized lower midline defect. Computed tomography (CT) scans revealed a hernia orifice 5 cm in width and 10 cm in height. As the hernia orifice was large, mesh reinforcement was essential. We planned for him to undergo VHR after massive weight loss was achieved by MBS. VHR was performed using the enhanced-view totally extraperitoneal (eTEP) technique after weight loss of 38 kg was achieved 9 months following laparoscopic sleeve gastrectomy. His postoperative course was uneventful, and neither recurrence nor seroma was observed at 1 year follow-up. CONCLUSIONS: eTEP repair of a ventral hernia after massive weight loss following MBS would appear to be the best combination treatment for obese patients with ventral hernias. However, long-term follow-up is necessary to establish its safety and efficacy.

Oncologic outcomes after laparoscopic versus open multivisceral resection for local advanced colorectal cancer: A meta-analysis.

Laparoscopic (lap) colectomies for advanced colorectal cancer (CRC) often require resection of other organs. We systematically reviewed currently available literature on lap multi-visceral resection for CRC, with regard to short- and long-term oncological outcomes, and compared them with open procedures. We performed a systematic literature search in MEDLINE, EMBASE, Google Scholar and PubMed from inception to November 30, 2020. The aim of this study was to synthesize short-term and oncological outcomes associated with laparoscopic versus open surgery. Pooled proportions and risk ratios (RRs) were calculated using an inverse variance method. We included six observational cohort studies published between 2012 and 2020 (lap procedures: n = 262; open procedures: n = 273). Collectively, they indicated that postoperative complications were significantly more common after open surgeries than lap surgeries (RR: 0.53; 95% confidence interval [CI]: 0.39-0.72; P < 0.00001), but the two approaches did not significantly differ in positive resection margins (RR: 0.75; 95% CI: 0.38-1.50; P = 0.42), local recurrence (RR: 0.66; 95% CI: 0.28-1.62; P = 0.37), or (based on two evaluable studies) 5-year OS (RR: 0.70; 95% CI: 0.46-1.04; P = 0.08) or 5-year DFS (RR: 0.86; 95% CI: 0.67-1.11) for T4b disease. In conclusion, laparoscopic and open multi-visceral resections for advanced CRC have comparable oncologic outcomes. Although a randomized study would be ideal for further research, no such studies are currently available.

[A long-surviving patient with unresectable advanced gastric cancer treated with S-1 and biweekly paclitaxel combination chemotherapy as second-line treatment].

A 59-year-old man with type 3 gastric cancer(signet-ring cell carcinoma)underwent simple laparotomy because of peritoneal dissemination.S -1/CDDP was started.Since the icterus of Grade 2 had appeared after 2 courses, S-1 and biweekly paclitaxel combination chemotherapy was started as second-line treatment.Throughout treatment, there was no adverse event, and this regimen was continued for 14 courses(25 months).He died 32 months after his first visit.S -1/PTX may play an important role as second-line chemotherapy for patients with unresectable advanced gastric carcinoma.

A case of sigmoid colon volvulus with transanal ileus tube placement and Sharon's operation performed safely.

Although endoscopic repair is often performed for sigmoid colon volvulus without intestinal necrosis, surgery is the common choice of treatment due to recurrence. With no established treatment, Hartmann's operation or sigmoid colon resection is often performed. We report a case of a 65-year-old man with transanal ileus tube placement before surgery for sigmoid colon volvulus to prevent recurrence and achieve intestinal decompression followed by Sharon's operation to achieve one-stage anastomosis. The patient showed good postoperative course, with no recurrence 3 months after surgery. This report discusses the usefulness of the transanal ileus tube and Sharon's operation for sigmoid colon volvulus without intestinal necrosis along with a review of the literature.

Initial entry via the left upper quadrant with an optical trocar in laparoscopic bariatric surgery.

INTRODUCTION: Laparoscopic bariatric surgery (BS) is not readily performed in Japan. To facilitate safe initial access to the abdominal cavity, we insert an optical viewing trocar at a unique site in the left upper quadrant (LUQ). Herein, we describe the technique, its advantages, and outcomes. MATERIALS AND SURGICAL TECHNIQUE: Briefly, the optical trocar is inserted just below the left subcostal margin, 8 cm from the midline. On insertion, layers of the abdominal wall are visualized on the monitor. Depending on the angle of insertion, five, seven, or eight layers are seen. DISCUSSION: In assessing our initial entry technique, used in 21 obese patients undergoing laparoscopic sleeve gastrectomy, we found median insertion time to be 25 seconds. There were no related complications. In nearly all (20/21) patients, the abdominal wall was visualized as seven layers: subcutaneous fat, anterior rectus sheath, rectus abdominis muscle, posterior rectus sheath, transverse abdominis muscle, transversalis fascia, and peritoneum. Understanding the layers of the abdominal wall visualized during optical trocar insertion in the LUQ will provide for safe and rapid initial entry in patients undergoing laparoscopic BS and can further the widespread acceptance of laparoscopic BS.

Perioperative complications and adverse events after lumbar spinal surgery: evaluation of 1012 operations at a single center.

BACKGROUND: Lumbar surgery and associated complications are increasing as society is aging. However, definitions of complications after lumbar surgery have not been established and previous reports have varied in the definition of, and focus on, intraoperative or major postoperative complications. We analyzed the frequency and severity of perioperative complications and all minor adverse events in lumbar surgery at a single center. METHODS: We retrospectively reviewed all lumbar surgery, including decompression surgery with or without fusion, at Meijo Hospital over a 10-year period. Perioperative complications and all surgery-related adverse events until 1 month postoperatively were reviewed for 1012 operations on 918 patients (average age 54 years old). The incidence of intraoperative complications was compared between junior (<10 years experience of spine surgery) and senior (≥10 years experience) surgeons. RESULTS: Perioperative complications and adverse events occurred in 159 operations (15.7%) on 127 patients (13.8%). There were a variety of perioperative adverse events, including digestive problems. Of the 159 complications and events, 24 (2.4%) were intraoperative and 135 (13.3%) were postoperative. Incidence of intraoperative complications was not significantly higher for junior surgeons; however, the operations performed by senior surgeons were significantly more invasive. Complications were more frequent in elderly patients (p < 0.01) and in operations that were longer (p < 0.0001), had greater estimated blood loss (p < 0.0001), and involved use of spinal instrumentation (p < 0.0001). Psychotic symptoms occurred significantly more often in older patients (p < 0.001). CONCLUSION: The absence of a relationship between the experience of the surgeon and incidence of intraoperative complications may be because of the greater effect of invasive surgery. Although age and invasiveness were associated with more perioperative adverse events, we do not conclude that major surgery should be avoided for elderly patients. In contrast, careful focus on the surgical indication and procedure is required for these patients.

Primary malignant melanoma of the esophagus successfully treated with nivolumab: a case report.

INTRODUCTION: Primary malignant melanoma of the esophagus is a rare and aggressive disease that tends to have a poor response to chemotherapies. Previous studies have indicated that currently available treatment for primary malignant melanoma of the esophagus is insufficient. Here, we describe a case of recurrent primary malignant melanoma of the esophagus successfully treated with the immune checkpoint inhibitor nivolumab. CASE PRESENTATION: An 81-year-old Japanese female presented with a 3-month history of dysphagia. She was medicated for hypertension and sarcoidosis. The patient had no past history of cutaneous, ocular, or other-site melanomas. An esophagoscopy identified a 30-mm giant tumor in the lower esophagus, at a site 30 cm from the incisors. Enhanced computed tomography revealed wall thickening measuring 30 mm in size at the middle-third of the intrathoracic esophagus, with no significant lymph node infiltration or distant metastasis. Esophageal biopsy showed proliferation of large round tumor cells and melanophages. On the basis of these findings, the patient was diagnosed with esophageal malignant melanoma and underwent esophagectomy and lymph node dissection with gastric tube reconstruction. Although the pathological diagnosis was primary malignant melanoma of the esophagus, the patient presented with multiple lymph node and bone metastases 4 months after surgery. Subsequently, treatment with nivolumab 240 mg every 2 weeks was administered as the first-line treatment. Diffusion-weighted imaging with background body signal suppression following eight courses of nivolumab revealed that the multiple lymph node and bone metastases were markedly reduced. The patient received 30 courses of nivolumab and has maintained the partial response. No severe adverse events related to the immunotherapy were recorded. CONCLUSION: The current study suggests that nivolumab may be a viable option for patients with metastatic primary malignant melanoma of the esophagus. Additional evidence from future clinical trials and research is necessary to fully validate these findings.

Successful one-stage laparoscopic procedure for de Garengeot hernia: a totally extraperitoneal repair-first approach.

The de Garengeot hernia is a femoral hernia in which the appendix migrates into the hernia sac. It is usually diagnosed intraoperatively due to its rarity and lack of clinical presentation typical to acute appendicitis. Although most cases need emergency operation due to incarceration, no standard procedure exists. We report the case of a 49-year-old woman who was diagnosed with a de Garangeot hernia preoperatively by contrast-enhanced computed tomography. She underwent one-stage laparoscopic surgery via a totally extraperitoneal approach followed by laparoscopic appendectomy. She recovered uneventfully and was discharged on postoperative Day 3. Generally, hernioplasty and appendectomy are required for the de Garengeot hernia treatment. Avoiding a peritoneal incision around the herniation and performing a mesh repair prior to appendectomy is expected to carry a lower infectious risk than other laparoscopic procedures. With accurate diagnosis, this procedure could be a useful modality for de Garengeot hernia.

Schwannoma of the gallbladder: report of a case.

We report a schwannoma of the gallbladder in a 58-year-old man who was diagnosed as cholecystolithiasis. He presented with recurrent episodes of abdominal pain in the right upper quadrant. The abdominal computed tomography scan and ultrasonography revealed stones about 15 mm in diameter in the gallbladder. Under the diagnosis of cholecystolithiasis, laparoscopic cholecystectomy was performed. The resected specimen showed chronic cholecystitis and no suspicion of neoplasm. Pathological examination revealed that the tumor consist of spindle cells without atypical appearance at small area of fundus. Immunohistologically, tumor cells were positive for S-100 protein and negative for alpha-SMA and c-kit, the lesion was diagnosed as schwannoma.

Laparoscopic transabdominal preperitoneal hernioplasty for recurrent obturator hernia: A case report.

Reports of recurrence after obturator hernia repair are few. We describe the case of an 89-year-old woman who presented to us with a thrice recurrent obturator hernia. She had undergone open non-mesh repair twice and then laparoscopic non-mesh repair. She was readmitted to our hospital 6 months after the laparoscopic repair. Manual reduction was successful, paving the way for elective transabdominal preperitoneal repair. During the endoscopic repair, surgical mesh was placed extraperitoneally over the hernia defect and then fixed to Cooper's ligament with absorbable tacks. The patient was discharged on postoperative day 2 without complications. In the 2 months that have passed since the surgery there has been no sign of recurrence, but the patient will be carefully followed up. Repair of a recurrent obturator hernia is technically challenging; however, the transabdominal preperitoneal approach seems to be reliable and safe.

Comparison of vertebral rotation corrected by different techniques and anchors in surgical treatment of adolescent thoracic idiopathic scoliosis.

STUDY DESIGN: Evaluation of radiographs and computed tomography in patients undergoing different surgical interventions for adolescent idiopathic scoliosis (AIS). OBJECTIVE: To compare the correction of vertebral rotation by different surgical techniques and/or anchors in the treatment of AIS. SUMMARY OF BACKGROUND DATA: The technique and the technology used in the surgical treatment of AIS continue to evolve; there is little information about the comparison of the vertebral rotation correction of thoracic scoliosis by different surgical techniques and/or anchors. METHODS: A retrospective study was performed on 106 consecutive patients with AIS, who underwent selective thoracic fusion with different surgical techniques and/or anchors, including hooks, wires, and pedicle screws on the periapical concave side from a posterior approach and an anterior approach using screws. The selection criteria were as follows: younger than 20 years of age, thoracic scoliosis (Lenke type 1, 2, and 3), selected thoracic fusion, and a minimum 2-year follow-up period, whereas thoracic hyperkyphosis was excluded. The patients were classified into group A (anterior approach, n=27), group H (hooks, n=39), group S (screws, n=25), and group W (wires, n=15). The Cobb angle and apical vertebral rotation were evaluated by plain radiography and computed tomography, respectively, before and after surgery and after 2 years of follow-up. RESULTS: All 4 groups were matched for age, sex, preoperative major curve, and curve flexibility. In all groups, the coronal Cobb angle was significantly improved after surgery, without any significant differences between the 4 groups. The Rotation Angle midline values in group A, group H, and group S were significantly improved after 2 years of follow-up (P<0.01), but not for group W. Rotation Angle sagittal was significantly improved after 2 years only in group A. Classification of each group into 2 subgroups according to the flexibility index (>0.5 and <0.5) provided Rotation Angle sagittal values that demonstrated significant improvement postoperatively (P<0.01) for group A and group S subgroups with a flexibility index >0.5. CONCLUSIONS: Compared with the use of hooks and the wires, vertebral rotation in AIS is effectively corrected by either the anterior approach or posterior pedicle screw fixation, especially in patients with more flexible scoliosis (a flexibility index >0.5).

Primary extraskeletal osteosarcoma of the mesentery: A case report.

INTRODUCTION: Extraskeletal osteosarcoma is a rare malignant soft tissue tumor without attachment to the bone. To the best of our knowledge, we present here the first report of a primary extraskeletal osteosarcoma of the mesentery in Japan. CASE PRESENTATION: A 46-year-old female underwent a health examination, with no complaint. Following an ultrasonography a solid mass was detected in the abdominal cavity. Computed tomography showed a 38 × 25 mm heterogeneously enhancing mass. The latter was characterized by the presence of mottled calcifications and a cystic portion. The tumor was resected with a single incisional laparoscopic curative resection. Histopathological examination revealed the presence of a primary extraskeletal osteosarcoma arising from the mesentery. Postoperative course was uneventful. The patient did not receive chemotherapy during follow-up. She was recurrence free 10 months post-surgery. DISCUSSION: Patients with extraskeletal osteosarcoma generally have a poor prognosis. A tumor size <5 cm represents an important prognostic factor. Unexpectedly, our case was detected by ultrasonography at an early stage. This is the first report of a single incisional laparoscopic resection. CONCLUSION: A primary extraskeletal osteosarcoma of the mesentery is an extremely rare occurrence. Its diagnosis should be taken into consideration also when a soft tissue mass of the mesentery is found.

Self-expanding metal stent restenosis in obstructive colon diverticulitis mimicking colon cancer: A case report.

INTRODUCTION: The self-expanding metal stent (SEMS) has been used in malignant colorectal obstruction as a bridge to surgery or for palliative treatment. We report a case of obstructive descending colon diverticulitis in-stent restenosis, which is difficult to distinguish from colon cancer. PRESENTATION OF CASE: A 48-year-old man presented with abdominal pain. Computed tomography demonstrated a segment of thickened wall in the descending colon with near-complete obstruction. Colonoscopy revealed stenosis over the entire circumference of the descending colon. Biopsy revealed no malignant findings. SEMS was inserted to improve bowel obstruction. However, bowel obstruction did not improve, and stent-in-stent insertion was performed. Because colon cancer could not be completely excluded, left hemicolectomy with lymph node dissection was performed. The pathological examination revealed colon diverticulitis and no malignant finding. DISCUSSION: Benign colorectal diseases can present with symptoms similar to those of obstructive colorectal cancer. As a result, it was benign colorectal stenosis, but it was thought that resection should be considered when the malignant lesion is suspected. The use of SEMS in benign colorectal disease has been reported a few. Reinsertion of the stent for restenosis, in bridge to surgery, was also considered useful from the viewpoint of avoiding emergent operation and reducing complications. CONCLUSION: For colon stenosis suspected of malignant disease, it was thought that resection by inserting SEMS should be taken into consideration even for benign disease as a result.

Combined laparoscopic abdomino-endoscopic perineal total mesorectal excision for anorectal malignant melanoma: A case report.

INTRODUCTION: This report presents a case of anorectal malignant melanoma treated with combined laparoscopic abdomino-endoscopic perineal total mesorectal excision. PRESENTATION OF CASE: An 82-year-old female presented with hematochezia. Colonoscopy revealed a 5-cm tumor in the anorectal junction, and biopsy specimen showed malignant melanoma. Modified ransanal total mesorectal excision was performed to get the sufficient surgical resection margins. After lymph node dissection in usual manner, mobilizing the rectum to the level of levator ani muscle. Then a skin incision was made around the anus and the transperineal access platform was placed. The fat tissue of the ischioanal fossa was divided until the levator ani muscle was exposed. The oral side of the colon was transected and specimen was extracted through the perineal incision site. Then stoma was placed laparoscopically. DISCUSSION: This procedure provides not only better exposure of the extralevator surgical field, but also efficient resection margins compared with the conventional andominoperineal resection. CONCLUSION: To the best of our knowledge, this is the first report of combined laparoscopic abdomino-endoscopic perineal total mesorectal excision for anorectal malignant melanoma. Our experience showed safety and feasible option for anorectal malignant diseases.

Thyrotropin-releasing hormone in the dorsal vagal complex stimulates pancreatic blood flow in rats.

Central administration of thyrotropin-releasing hormone (TRH) enhanced pancreatic blood flow in animal models. TRH nerve fibers and receptors are localized in the dorsal vagal complex (DVC), and retrograde tracing techniques have shown that pancreatic vagal nerves arise from the DVC. However, nothing is known about the central sites of action for TRH to elicit the stimulation of pancreatic blood flow. Effect of microinjection of a TRH analog into the DVC on pancreatic blood flow was investigated in urethane-anesthetized rats. After measuring basal flow, a stable TRH analog (RX-77368) was microinjected into the DVC and pancreatic blood flow response was observed for 120 min by laser Doppler flowmetry. Vagotomy of the several portions, or pretreatment with atoropine methyl nitrate or N(G)-nitro-l-arginine-methyl ester was performed. Microinjection of RX-77368 (0.1-10 ng) into the left or right DVC dose-dependently increased pancreatic blood flow. The stimulation of pancreatic blood flow by RX-77368 microinjection was eliminated by the same side of cervical vagotomy as the microinjection site or subdiaphragmatic vagotomy, but not by the other side of cervical vagotomy. The TRH-induced stimulation of pancreatic blood flow was abolished by atropine or N(G)-nitro-l-arginine-methyl ester. These results suggest that TRH acts in the DVC to stimulate pancreatic blood flow through vagal-cholinergic and nitric oxide dependent pathways, indicating that neuropeptides may act in the specific brain nuclei to regulate pancreatic function.

Protective effect of central thyrotropin-releasing hormone analog on cerulein-induced acute pancreatitis in rats.

Central neuropeptides play a role in many physiological functions through the autonomic nervous system. We have recently demonstrated that central injection of a thyrotropin-releasing hormone (TRH) analog increases pancreatic blood flow through vagal and nitric oxide-dependent pathways. In this study, the central effect of a TRH analog on experimental acute pancreatitis was investigated in rats. Acute pancreatitis was induced by two intraperitoneal injections of cerulein (40 microg/kg) at 1-h interval. Either stable TRH analog, RX 77368 (5-100 ng), or saline was injected intracisternally 15 min before the first cerulein injection under ether anesthesia. Serum amylase level was measured before and 5 h after the first cerulein injection. Pancreatic wet/dry weight ratio and histological changes were also evaluated. Intracisternal TRH analog inhibited cerulean-induced elevation of serum amylase level, increase in pancreatic wet/dry weight ratio and pancreatic histological changes, such as interstitial edema, inflammation and vacuolization. The pancreatic cytoprotection induced by central TRH analog was abolished by subdiaphragmatic vagotomy and N(G)-nitro-L-arginine-methyl ester (L-NAME), but not by 6-hydroxydopamine (6-OHDA). Intravenous administration of the TRH analog did not influence cerulein-induced acute pancreatitis. These results indicate that the TRH analog acts in the central nervous system to protect against acute pancreatitis through vagal and nitric oxide-dependent pathways.

Effect of central thyrotropin-releasing hormone on pancreatic blood flow in rats.

Central neuropeptides play a role in physiological regulation through the autonomic nervous system. Thyrotropin-releasing hormone (TRH) is a neuropeptide distributed throughout the central nervous system and acts as a neurotransmitter to regulate gastric and hepatic functions through vagal-cholinergic pathways. In this study, the central effect of TRH on pancreatic blood flow was investigated in urethane-anesthetized rats. Pancreatic blood flow was determined by laser Doppler flowmetery. After measurement of basal blood flow, a stable TRH analog, RX 77368 (1-50 ng) or saline was injected intracisternally. Pancreatic blood flow was observed for 120 min thereafter. In some experiments, pretreatment with atropine methyl nitrate (0.15 mg/kg, i.p.), NG-nitro-L-arginine-methyl ester (10 mg/kg, i.v.), or 6-hydroxydopamine (6-OHDA;180 mg/kg, i.p.), or subdiaphragmatic vagotomy was performed. Intracisternal injection of TRH analog dose-dependently increased pancreatic blood flow with a peak response occurring 30 min after injection. The stimulatory effect of TRH analog on pancreatic blood flow was blocked by vagotomy, atropine, and NG-nitro-L-arginine-methyl ester, but not by 6-hydroxydopamine. Intravenous administration of the TRH analog did not influence pancreatic blood flow in the same animal model. These results indicate that TRH acts in the central nervous system to stimulate pancreatic blood flow through vagal-cholinergic and nitric oxide-dependent pathways.

A case of perianal mucinous adenocarcinoma arising from an anorectal fistula successfully resected after preoperative radiotherapy.

A case of mucinous adenocarcinoma arising on a long-standing anorectal fistula is described. A 60-year-old man with a long history of mucinous discharge, pain and perianal induration underwent a biopsy of the external opening of the fistula that showed a mucinous infiltrating adenocarcinoma. Due to the large size of the tumor and the fact that it had extended into the surrounding tissue, preoperative radiotherapy was performed. Radiotherapy was given with 40 Gy in 25 fractions for 5 weeks through posterior and bilateral portals. After radiotherapy the tumor was markedly shrunk and the serum level of carcinoembryonic antigen was also improved. Abdominoperineal resection was performed 8 weeks after the termination of radiotherapy. Histological examination of the resected specimen revealed that the invasion of the tumor remained within the sphincter muscle and that no cancer cells were present on the surgical margin. The histological effect of radiotherapy was judged as grade 1b. This treatment can result in downstaging and R0 resection, which also has a possibility to prevent local recurrence. This case suggests that preoperative radiotherapy may play an important role in the definitive treatment of locally advanced perianal mucinous adenocarcinoma.