A male in his 70s underwent laparoscopic-assisted high anterior resection and D2 lymph node dissection for rectal cancer (pT3, pN1a, M0, fStage ⅢB)3 years ago. Postoperative adjuvant chemotherapy was not administered due to diabetic nephropathy. Three years post-surgery, plain CT and PET-CT revealed recurrent liver metastasis at the bifurcation of the anterior and posterior liver segments. Right hepatic lobectomy was planned following portal vein embolization, as his ICG R15 was 18.9%, indicating insufficient residual liver volume after resection. To avoid frequent contrast-enhanced CT scans due to low renal function, 4D flow-MRI was performed before portal vein embolization and on the third day post-embolization to measure portal blood flow velocity and volume. These measurements were applied to the estimated residual liver volume formula to predict the residual liver volume 28 days later. The predicted residual liver volume on the 28th day was 469 mL(64%), and CT volumetry performed on the same day showed a volume of 471 mL. Right hepatic lobectomy was performed without worsening liver or kidney function. This case report demonstrates that using 4D flow-MRI can accurately predict the residual liver volume after portal vein embolization, enabling safe curative resection in patients for whom contrast-enhanced CT is challenging due to renal impairment.

Cholangiocellular carcinoma(CoCC)is a rare form of primary liver cancer. We report 2 cases of cholangiocellular carcinoma(CoCC). Case 1: 66-year-old male. He was initially diagnosed as a suspected hepatic hemangioma and followed up, but 5 months later, contrast-enhanced MRI showed an increasing trend, and he was diagnosed as intrahepatic cholangiocarcinoma and underwent surgery. Case 2: 73-year-old female. She was suspected to have hepatic hemangioma. Eight months later, contrast-enhanced MRI showed an enlargement of 20 mm in size, which led to suspicion of hepatocellular carcinoma or intrahepatic cholangiocarcinoma, and surgery was performed. The pathological diagnosis of both patients was CoCC.

A 42-year-old male was referred to our hospital for epigastric and back pain. Following a diagnosis of acute pancreatitis, abdominal CT revealed a low-density tumor measuring 15 mm in diameter in the pancreatic body. Endoscopic retrograde pancreatography showed narrowing of the main pancreatic duct, and cytology of pancreatic juice indicated class Ⅲ. Given the strong suspicion of pancreatic cancer, a distal pancreatectomy was performed. Pathological examination confirmed spindle cell-type anaplastic carcinoma of the pancreas, categorized as pT2, pN0, M0, and pStage ⅠB. Local recurrence and liver metastasis were observed on postoperative day 72. The tumor progressed rapidly, leading to the patient's death on postoperative day 115. Anaplastic carcinoma of the pancreas has a poor prognosis, emphasizing the urgent need for establishing multidisciplinary treatment.

Conversion surgery means surgery for initially unresectable tumors which are converted to resectable tumors by multidisciplinary treatment. Since the introduction of highly effective drug therapies including immune checkpoint inhibitors for hepatocellular carcinoma(HCC), conversion surgery for HCC has become a common experience. Recently, the Japanese Expert Consensus 2023 have reported on the oncological criteria of resectability for HCC, allowing us to use common terms to describe unresectable HCC, which had been ambiguously defined in the past. HCC cases are classified into 3 criteria, based on the tumor number and size, the degree of vascular invasion, and the degree of extrahepatic involvement. The 3 criteria are R(resectable; oncological status for which surgery alone may offer clearly better survival outcomes compared to the other treatment), BR1(borderline resectable 1; oncological status for which surgical intervention as a part of multidisciplinary treatment may offer survival benefit), and BR2(borderline resectable 2; initially unsuitable for resection: oncological status for which efficacy of surgery is indeterminate and surgical indication should be carefully determined under the standard multidisciplinary management of HCC). Whether conversion surgery improves prognosis under the assumption that nonsurgical treatment such as drug therapy has been successful is a question for further investigation.

Pancreatic cancer is known as a disease with an extremely poor prognosis. Although surgery is the only curative treatment, most pancreatic cancer is already advanced at the time of diagnosis. With advances in multidisciplinary treatment such as chemotherapy, radiation therapy, and heavy-ion therapy, more cases of unresectable(UR)pancreatic cancer are being treated with surgery in recent years. Therefore, the term"conversion surgery"has been newly included in the 8th edition of the General Rules for Study of Pancreatic Cancer, and the treatment strategy for UR pancreatic cancer has entered a new phase. Conversion surgery for UR-LA pancreatic cancer is expected to be effective as the indications for chemoradiation and heavy-ion radiation therapy expand. On the other hand, UR-LA pancreatic cancer is not only a locally advanced disease but also a systemic disease, and there have been reports of patients with early postoperative recurrence, so the indication for surgery remains a controversial field. Furthermore, there are increasing reports of conversion surgery for UR-M pancreatic cancer. There are concerns about complications and increased mortality due to extended resection, and early recurrence, so usefulness is not clear at present. Among UR-M, positive peritoneal washing cytology(CY1)is considered to be a preliminary stage of peritoneal dissemination, and is now treated as distant metastasis since the 8th edition of General Rules. CY-positive pancreatic cancer is easier to control than other distant metastases, and CY-negative conversion is expected to be equivalent to that of patients with CY0 at the initial diagnosis. Further evidence for multidisciplinary treatment, including conversion surgery, is expected to be accumulated.

Conversion surgery for gastric cancer is defined as surgery for tumors with distant metastases that are technically or oncologically unresectable at diagnosis, with the aim of achieving R0 resection after chemotherapy. However, there is no randomized controlled trial evidence comparing conversion surgery with continued chemotherapy at the stage of response to chemotherapy. In addition, there are no recommendations on appropriate targets, timing of surgery, extent of resection, pre-and post-operative chemotherapy regimens or duration of chemotherapy, which are issues that need to be resolved. A randomized controlled phase Ⅲ trial is currently underway to address these clinical questions, and it is hoped that this will provide some answers to the long debated significance of conversion surgery.

We report a patient achieving curative resection of synchronous pancreatic and rectal cancers with neoadjuvant chemotherapy. A 71-year-old man was diagnosed with pancreatic head cancer and rectal cancer on close examination for epigastralgia. Abdominal computed tomography showed the pancreatic head cancer had semi-peri-circumferential abnormal invasion into the superior mesenteric vein(SMV), so we diagnosed the tumor as borderline resectable(BR)pancreatic cancer. Colonoscopy revealed a type 1 tumor in the rectum, and biopsy detected a well-differentiated adenocarcinoma. We administered mFOLFIRINOX as preoperative chemotherapy for BR pancreatic cancer, but there was no effect. After the change to GnP, the tumor was reduced and the extent of SMV involvement was also reduced, so pancreaticoduodenectomy(PD)was performed. There was no portal vein invasion of the tumor and R0 resection was achieved. Two months after PD, laparoscopic low anterior resection was performed for rectal cancer. The patient's postoperative course was uneventful, and he had no recurrence in 8 months.

A 73-year-old woman, taking antiviral medication for hepatitis B virus, underwent radiofrequency ablation(RFA)for hepatocellular carcinoma(HCC)in the anterior segment of the liver. Six months, 24 months, and 32 months after the first treatment, RFA was performed for non-local recurrent HCC in segment 4, segment 5, and segment 5, respectively. Nine years and 7 months after the first RFA, a new lesion in the liver, close to the location of the first lesion, was detected on CT and MRI. Simultaneously, a tumor with a diameter of 9 mm was detected in the neck of the pancreas. Laparoscopic anterior segmentectomy of the liver was performed, followed by laparoscopic middle pancreatectomy 10 days later. Pathological study of the specimen revealed biloma in the region of the first RFA and a tumor close to the biloma consisted of HCC partially mixed with cholangiolocellular carcinoma, which is classified as combined hepatocellular-cholangiocarcinoma in the 5th edition of the WHO classification. The tumor in the neck of the pancreas was a poorly differentiated adenocarcinoma without lymph node metastasis. The patient has remained alive for 18 months post-surgery, without recurrence. It is difficult to differentiate HCC from cholangiolocarcinoma or combined hepatocellular-cholangiocarcinoma. Therefore, in case of multiple liver cancers, the intermingling of those tumors should be considered.

An 81-year-old woman was diagnosed with a tumor in the pancreas, detected on CT and MRI. The tumor was 12 mm in diameter and located close and in the distal side of the branch duct-type intraductal papillary mucinous neoplasm(IPMN)in the pancreas head observed for 4 years. Pancreatic ductal adenocarcinoma derived from IPMN was suspected and pylorus-preserving pancreatoduodenectomy was performed. The immunohistological diagnosis of the tumor using a resected specimen was diffuse large B cell lymphoma of the pancreas. After surgery, chemotherapy was not performed because of the patient's decision, but 2 years later, relapse of malignant lymphoma was suspected because of swelling of the bilateral adrenal glands on MRI. R-CHOP immunochemotherapy was started, but seven months later the patient died of lymphoma involving the central nervous system. Primary pancreatic lymphoma(PPL)is a rare disease representing 0.6% of extranodal lymphoma. Many cases of PPL are large, and small lesions under 2 cm in diameter are extremely rare. Furthermore, PPL associated with IPMN has never been reported. The pancreatic tumor close to the IPMN is difficult to diagnose differentially from adenocarcinoma on radiological findings. However, nonsurgical biopsy of the tumor in the pancreas is sometimes challenging if associated with IPMN.

A 40-year-old woman was diagnosed with ipsilateral breast tumor recurrence in the conserved breast 1.5 years after undergoing partial mastectomy for right breast cancer at another hospital. She was referred to our hospital at 19 weeks of gestation. At 21 weeks, total mastectomy of the conserved breast with sentinel lymph node biopsy was performed. The postoperative pathological diagnosis was invasive ductal carcinoma mixed with squamous cell carcinoma. AC chemotherapy was initiated at 33 weeks, and she gave birth by cesarean section at 39 weeks. Postpartum, EC therapy followed by paclitaxel therapy were administered. Currently, she is on endocrine therapy, with no new recurrence observed for 3 years after surgery. Pregnancy-associated breast cancer is rare, accounting for approximately 1% of all breast cancers, and there are few reports on the treatment of local recurrence or distant metastasis during pregnancy. This case, involving breast-conserving surgery recurrence during pregnancy, highlights the importance of careful decision-making and treatment strategies tailored to individual cases, considering the safety of both mother and fetus through multidisciplinary collaboration.

Herein we report on a case of gastric GIST that recurred locally 11 years after surgery, which was successfully resected. The case concerned a male patient in his 70s. In March 2011, the patient underwent proximal gastrectomy for a submucosal tumor in the gastric cardia. The patient was diagnosed with high-risk GIST based on the pathological findings and was treated with imatinib as postoperative adjuvant therapy for 3 years. The patient then continued follow-up as an outpatient. A follow-up CT scan performed in March 2022 showed a mass shadow on the ventral side of the esophagogastric anastomosis, and a biopsy revealed a diagnosis of GIST. The tumor was resected locally as a recurrent gastric GIST.

A 76-year-old man with sigmoid colon cancer and gastric cancer was referred to our hospital because of severe anemia. Computed tomography revealed peritoneal dissemination and lung metastasis. For diagnoses of cStage Ⅳa sigmoid cancer and cStage ⅣB gastric cancer, palliative laparoscopic sigmoidectomy and distal gastrectomy were planned in order to avoid tumor hemorrhage and intestinal obstruction. Intraoperative findings suggested cancer dissemination on the pelvic peritoneum, thus laparoscopic Hartmann's procedure and distal gastrectomy were performed. The final diagnosis was sigmoid colon cancers, ①pT4, ②pT2N2aM1c2(P2, PUL1), pStage Ⅳc and gastric cancer, pT4aN1M1(PER), pStage Ⅳ. The resected specimen showed collision tumors consisting of sigmoid colon cancer(CK20+/CK7-)and dissemination of gastric cancer (CK20-/CK7+)confirmed by immunohistochemistry. Postoperatively, the patient underwent chemotherapy for gastric cancer. We report here a rare case of collision tumor consisting of a sigmoid colon adenocarcinoma and peritoneal dissemination of gastric adenocarcinoma.

A woman in her 50s presented to our department of plastic surgery with a complaint of a nodule in the umbilical region. CT revealed an umbilical tumor and thickening of the anterior wall of the stomach, raising suspicion of gastric cancer with umbilical metastasis. She was referred to surgery. Upper endoscopy identified advanced gastric cancer(type 2)in the greater curvature of the gastric body. PET-CT showed abnormal uptake in the greater curvature of the gastric body, umbilical region, right ovary, and lymph nodes. She was diagnosed with gastric cancer(T4aN3aM1, cStage ⅣB)and underwent chemotherapy. A CT scan after the fourth course showed significant tumor shrinkage, making identification difficult. After 9 months of chemotherapy, upper endoscopy showed marked tumor shrinkage, and CT and PET-CT scans showed that the primary and metastatic lesions were indistinguishable. Exploratory laparoscopy and umbilical biopsy revealed no gross dissemination, and histologically, no tumor cells were found in the umbilical area or ascites. Conversion surgery was deemed appropriate and performed, including distal gastrectomy with bilateral salpingo-oophorectomy. No metastases were found in the lymph nodes or adnexa, and she was diagnosed with ypStage ⅠB(T2N0M0). Adjuvant chemotherapy was administered, and she remains recurrence-free 14 months post-surgery.

A 74-year-old man had locally advanced esophageal cancer with a tracheal diverticulum(cT3brN2M0, cStage ⅢB). After induction chemoradiotherapy, consisting of 3 courses of mFOLFOX therapy and 40 Gy radiotherapy, thoracoscopic radical esophagectomy was performed safely without tracheal injury. Histopathological findings showed that the therapeutic effect was Grade 3. Esophageal cancer has been recurrence-free for 1 year and 3 months after surgery.

We report a case of breast cancer with intramammary lymph node metastasis found after surgery without sentinel lymph node metastasis. A 30's female came to our hospital for a detailed examination after undergoing breast cancer screening. Mammography and ultrasonography showed a mass in the upper-outer quadrant of her right breast. With a core needle biopsy, a diagnosis of invasive breast cancer was achieved. A right lumpectomy and sentinel lymph node biopsy was carried out. The sentinel lymph nodes were confirmed to be negative for metastasis during the surgery. Pathological findings revealed invasive lobular carcinoma in the upper-outer quadrant and a positive intramammary lymph node. We decided to perform no additional axillary lymph node dissection considering the result of ACOSOG Z0011. The patient is currently undergoing adjuvant therapy and is under observation.

A 72-year-old man who had received total gastrectomy for gastric cancer(MU, circ, Type 3, pT4b[SI: transverse colon], N3b, M1[CY1], pStage Ⅳ). He underwent postoperative adjuvant chemotherapy(S-1)for 6 months after surgery. Four years and 4 months after surgery, a 3 cm-sized mass was found at the pancreatic tail, and the mass was suspected of pancreatic metastasis from gastric cancer or primary pancreatic cancer. Distal pancreatectomy was performed. The operation time was 4 hours and 56 minutes, the blood loss 250 g. A minor leak in the transverse colon was observed after the surgery, and he was treated conservative measures. He was discharged from the hospital 24 days after the surgery. Pathological examination found that the mass was pancreatic metastasis of gastric cancer. After the operation, he was treated with DS therapy(S-1+docetaxel)for 1 year and has been alive without recurrence for 4 years and 2 months after resection of the recurrent tumor. Gastric cancer pancreatic metastasis is rare, but if the tumor is solitary, resection can be expected to result in long-term recurrence-free survival.

A 73-year-old man was transferred to our hospital with high fever. Computed tomography(CT)showed pancreatic tail cancer invading the stomach, colon, spleen and retroperitoneum around the left kidney. Splenic abscess with air was also observed. Marked increase in WBC and CRP were observed and the CA19-9 level was also elevated to 1,030 U/mL. The patient was diagnosed with pancreatic tail cancer invading to surrounding organs with splenic abscess due to penetration of the colon. Then emergency surgery was performed. Distal pancreatectomy with splenectomy, total gastrectomy and partial colectomy was performed. Pathological examination showed a moderately differentiated adenocarcinoma of the pancreatic tumor with invasion of other organs (stomach, colon, spleen and greater omentum). The postoperative course was uneventful and the patient was discharged 22 days after surgery. The patient is currently receiving adjuvant chemotherapy without recurrence. In the case of pancreatic tail cancer invading surrounding organs with splenic abscess, it is important to perform en bloc resection of tumor and invading surrounding organs and to start early postoperative chemotherapy for better survival.

The patient was a 74-year-old man. He was referred to our institution due to bloody stool and multiple liver tumors. Close examination revealed primary colon cancer in the splenic flexure of the colon and multiple liver metastases(up to 6.5 cm, 16 in total)in both lobes of the liver, and he was finally diagnosed with transverse colon cancer(cT3N+M1a[H3], cStage Ⅳa). As the liver metastases were unresectable and the primary tumor was not stenosed, the patient was treated with chemotherapy. As RAS/BRAF mutation was negative, the chemotherapy with FOLFOX and panitumumab were administered. After 6 courses of chemotherapy, the primary and metastatic tumors were reduced had shrunk and CEA value had decreased. The liver metastases were concentrated in the right lobe of the liver, and radical resection was considered possible with right lobectomy and partial resection of the left lobe of the liver. As the residual liver fraction was expected to be 33%, one-stage hepatectomy was too risky and the two-stage hepatectomy was chosen. Laparoscopic left hemicolectomy and laparoscopic partial resection of the liver(S3 and S4, 4 tumor resections in total)were performed at the first operation. On postoperative day 8, the percutaneous transhepatic portal vein embolization(PTPE)of the right lobe of the liver was performed, and the expected residual liver fraction was increased to 40% 2 weeks after PTPE. The laparoscopic right lobectomy of the liver was performed on day 20 after PTPE. The patient has had no major complications or recurrences to date. We report a case in which R0 was achieved after aggressive chemotherapy and laparoscopic two-stage hepatectomy.

Para-aortic lymph node metastasis(PALNM)is classified as distant metastasis in colorectal cancer(CRC). Although the benefit of para-aortic lymph node dissection(PALND)for the CRC patients with PALNM suspected radiologically remains controversial, some reports have shown that the survival benefit for PALND in CRC patients with PALNM. Moreover, the report evaluating the extent of PALND showed that the patients treated with radical lymphadenectomy had better prognosis compared to those treated with targeted lymphadenectomy defined as the dissection of only swollen lymph nodes. We have performed the laparoscopic PALND for selected CRC patients with PALNM. Three radical dissections using retroperitoneoscopy have been performed in 9 CRC patients who underwent PALND in the last 6 years. Now, we show one of the effective cases treated with the retroperitoneoscopic radical resection. We additionally mention the effectiveness of the retroperitoneoscopic radical resection for the patients with PALNM. The retroperitoneoscopic resection resulted in more blood loss and longer operative time than laparoscopic resection, however, more lymph nodes were resected. The retroperitoneoscopic radical resection may be the preferable procedure for the CRC patients with PALNM, especially for the patients with multiple or extensively spread PALNM.

A 77-year-old male patient with cT4N1aM1(PUL1), cStage Ⅳ rectal cancer underwent low anterior resection in Y20XX with a plan to perform pneumonectomy after resection of the primary tumor. The pathological diagnosis was pT3N0M1 (PUL1), pStage Ⅳ mucinous adenocarcinoma ly1, v1, pPM0, pDM0. A thoracoscopic left lung S4 segmentectomy was performed Y+2 months later and a thoracoscopic right upper lung partial lobectomy was performed Y+6 months later. However, a small nodule appeared in the lower lobe of the right lung on postoperative follow-up CT and continued to grow, so a partial resection of the lower lobe of the right lung was performed Y+12 months later. However, a 6 mm-sized mass appeared in the left upper lobe of the lung on postoperative follow-up CT, and it continued to grow, so partial resection of the left upper lobe was performed Y+20 months later. Both pathological diagnoses were pulmonary metastasis of rectal cancer. Since the patient had had 3 metastatic recurrences at this point, postoperative adjuvant chemotherapy(S-1)was administered from Y+22 months. Since then, the patient has been alive without metastasis or recurrence, and is still recurrence-free 14 years after the last pneumonectomy.