Recent data showed that DNA mismatch repair deficiency can be a predictive biomarker for a favorable response of immune checkpoint inhibitors regardless of tumor type due to give rise to high tumor mutational burden (TMB) and microsatellite instability (MSI). Loss-of-function mutations of a specific tumor suppressor gene can also lead to good response to immunotherapy. Herein, we report a case exhibiting good response to pembrolizumab in a jejunal adenocarcinoma patient with low programmed death-ligand 1 (PD-L1) expression. A 67-yearold man underwent surgical resection followed by adjuvant chemotherapy. After 10 months, he was treated with palliative chemotherapy due to hepatic and pulmonary metastases. However, palliative chemotherapy did not have any effect whatsoever. Based on genetic testing results of high TMB and high MSI in the resected primary tumor, pembrolizumab treatment was performed. After the three cycles of treatment, all metastatic lesions shrank remarkably. Considering the mechanism of immune checkpoint inhibitors, this case establishes the importance of genetic markers as TMB and MSI rather than PD-L1 expression by the prediction of their anti-tumor activities.

Purpose: As we enter an aging society, the number of elderly patients with breast cancer is increasing. We assessed the prognostic factors for breast cancer recurrence or metastasis in patients over the age of 65 years by analyzing tumor characteristics and long-term clinical outcomes. Methods: In this retrospective study, the data of 286 breast cancer patients aged 65 years and older, who underwent treatment at the Pusan National University Hospital and Pusan National University Yangsan Hospital from 2008 to 2014, were analyzed. The patients were divided into two groups: those with recurrence or metastasis and those without. Cox-regression model was used to analyze the risk factors for recurrence or metastasis. Kaplan-Meier method was used to analyze survival rates by the log-rank test. Results: Among the 286 patients with invasive breast cancer, 43 patients (15.0%) had recurrence or distant metastasis during a median follow-up period of 61 months. Advanced stages of breast cancer and patients who are not adapted to endocrine therapy were associated with poor prognosis. Conclusion In this study, advanced stages of breast cancer and endocrine therapy were the prognostic factors for breast cancer recurrences or metastases. Early detection of elderly breast cancer generally increases the possibility of diagnosis at an earlier stage, which can lead to a better prognosis. Moreover, endocrine therapy should be administered to elderly patients who manifest favorable intrinsic subtypes of breast cancer.

Purpose: Totally laparoscopic distal gastrectomy (TLDG) is now widely used for early gastric cancer patients, but the selection of a reconstruction method after TLDG is still controversial. Roux-en-Y gastrojejunostomy is increasingly used in expectation of less gastritis and alkaline reflux despite its technical difficulty. The uncut Roux-en-Y gastrojejunostomy (uRYGJ) retains the advantages of Roux-en-Y reconstruction but helps prevent Roux stasis syndrome. The present study aims to introduce a single surgeon’s experience of TLDG with uRYGJ and analyze the learning curve and surgical outcomes. Methods: We retrospectively reviewed the medical records of 124 consecutive patients who underwent TLDG with uRYGJ performed by a single surgeon between July 2014 and August 2015 at Asan Medical Center. The baseline characteristics and surgical outcomes were analyzed, and the learning curve was drawn based on the power-law model. Results: The mean total operative time was 165 minutes, and the average length of hospital stay was 6.6 days. Complications included two cases of duodenal stump leakage, two intra-abdominal bleeding, two intra-abdominal fluid collection, one wound problem, two anastomotic strictures, 14 ileus, and no anastomotic leakage. There were five cases of endoscopically proven reflux gastritis/esophagitis and no Roux stasis syndrome. There were five recurrences and one mortality during the follow-up period. The learning curve leveled at the 15th case. Conclusion The results of our study showed the safety and feasibility of uRYGJ, and that the technical difficulty of the procedure can be overcome with a short learning curve for experienced surgeons.

Purpose: High incidence of osteoporosis has been reported in breast cancer patients due to early menopause triggered by adjuvant treatment and temporary ovarian function suppression. In this study, we sought to determine whether long-term breast cancer survivors had an elevated risk of low bone density compared to the general population. Methods: Long-term breast cancer survivors who had been treated for more than 5 years were selected for this study. Data were obtained from medical records and using a questionnaire from the Korea National Health and Nutrition Examination Survey (KNHANES). An agematched non-cancer control group was selected from the KNHANES records. Incidence of fracture and bone mineral density (BMD) were compared between the two groups. Results: In total, 74 long-term breast cancer survivors and 296 non-cancer controls were evaluated. The incidence of fracture did not differ between the two groups (P=0.130). No differences were detected in lumbar BMD (P=0.051) following adjustment for body mass index, while hip BMD was significantly lower in breast cancer survivors (P=0.028). Chemotherapy and endocrine treatment were not related to low BMD in breast cancer survivors. In more than half of the survivors, the 10-year risk of osteoporotic fracture was less than 1%. Conclusion Long-term breast cancer survivors had low bone density but a comparable risk of fracture compared to non-cancer agematched controls. Further studies on the factors related to low bone density in long-term breast cancer survivors are required.

Purpose: The extent of surgery necessary in patients with unilateral papillary thyroid carcinoma (PTC) on preoperative radiologic imaging is still in doubt. In this study, we aimed to define risk factors that could be indicators for malignant nodules in the contralateral thyroid lobe. Methods: We included 438 patients who underwent total thyroidectomy between January 2011 and December 2014 at our institution. In this study, patients were divided into two groups according to the presence of contralateral occult carcinoma identified by postoperative pathological examination. We analyzed the clinicopathologic factors including characteristics of coexistent nodules in the contralateral lobe based on preoperative radiological imaging. Results: A total of 96 patients (21.9%) had PTC in the contralateral lobe. There were no significant differences between patients with or without contralateral occult carcinoma with respect to gender, age, primary tumor size, central lymph node metastasis, extrathyroidal extension and stage. The presence of Hashimoto’s thyroiditis was an independent predictive factor for contralateral occult carcinoma (P=0.01). Conclusion A risk factor for contralateral occult carcinoma in unilateral PTC patients is Hashimoto’s thyroiditis. Therefore, more caution is needed when determining optimal surgical methods for PTC patients with Hashimoto’s thyroiditis.

Purpose: The incidence of poorly differentiated thyroid carcinoma (PDTC) is extremely low among thyroid cancers and there is no standardized treatment guideline for it. In this study, we have analyzed PDTC patients and reviewed their clinicopathological features. Methods: Data of PDTC patients from our institution are collected through the electronic medical database. We analyzed them by several parameters such as basic demographics, presenting symptom, preoperative cytology results, associated pathology, surgical results, surgery type, and distant metastasis. Results: We collected 23 cases in our institution. Apart from two patients who were transferred to another hospital upon diagnosis, all 21 operated cases are analyzed. The parameters we studied were age, sex, presenting symptoms, distant metastasis and pathological features such as tumor size, associated pathology, predominant pattern and so on. We also provided descriptive analyses according to the type of presentation and treatment; patients with distant metastasis, juvenile cancer, and concurrent hyperthyroidism. Furthermore, we provided different cases in which the initial surgical plans differed. Conclusion We present 21 cases of PDTC patients and clarify their clinicopathological features. Despite some limitations, this study may shed light for future research regarding treatment of PDTC patients.

Purpose: The ACOSOG Z0011 trial has proven the oncological safety of sentinel lymph node biopsy (SLBx) for node negative breast cancer. Accordingly, treatment paradigm including axilla surgery was changed. We retrospectively reviewed breast cancer patients to evaluate the clinical effect of paradigm shift in breast cancer surgery after applying the Z0011 criteria. Methods: All women who underwent breast-conserving surgery at the National Cancer Center between January 1, 2000, and December 31, 2015, were enrolled and classified according to the Z0011 criteria. The primary endpoint of the study was the disease-free survival rates, and the secondary was the adverse events, especially arm lymphedema. Results: Total 361 patients were enrolled the study (271 axillary lymph node dissection [ALND] group, 90 SLBx group). After the Z0011 guideline was adopted in our institute, the use of ALND decreased, and lymph node sampling (removing only a few axillary lymph nodes) replaced ALND. The total mean number of retrieved nodes were more in ALND group (13.02) than SLBx group (3.43). However, there was no difference in the mean number of positive nodes between two groups (2.34 in ALND group vs. 1.12 in SLBx group, P=0.001). During follow-up, 25 patients experienced disease recurrence: 22 from the ALND group and three from the SLBx group. All of died seven patients were from the ALND group. The ALND group had more complications than the SLBx group (P=0.02). Arm edema occurred more frequently in the ALND group (29.5%) than in the SLBx group (5.6%), although without statistical significance (P=0.07). Conclusion In our study, we concluded that SLBx can be used safely in Z0011-eligible cohort without increased risk of locoregional recurrence. Moreover, we found that omission of ALND is favored to reduce some serious complications such as arm lymphedema.

Purpose: Early initiation of adjuvant chemotherapy after colon cancer surgery has shown better oncologic outcomes in previous studies. However, the clinical impact of robotic and laparoscopic surgeries on the initiation of adjuvant chemotherapy has not been widely evaluated. Hence, the study’s aim was to compare the influence of both surgical approaches on the initiation of adjuvant chemotherapy after colon cancer surgery. Methods: From June 2011 to September 2017, 289 patients underwent curative robotic or laparoscopic surgery followed by adjuvant chemotherapy for stage II and III colon cancer. To control for different demographic factors in the two groups, propensity score case matching was used at a 1:4 ratio. Finally, 190 patients were matched with 38 patients of the robotic surgery group and 152 patients of the laparoscopic surgery group. Results: The operation time was longer in the robotic surgery group (297 minutes vs. 170 minutes, respectively; P<0.001). However, conversion rate, number of retrieved lymph nodes, first flatus, first soft diet, length of stay, postoperative complication rate, and Clavien-Dindo grade were not significantly different between the two groups. Additionally, there was no difference in the time to initiation of adjuvant chemotherapy between the two groups (31.5 days vs. 29.0 days, respectively; P=0.226). Disease-free and overall survival rates were also not significantly different. Conclusion Robotic and laparoscopic surgeries showed no different impact on the initiation of adjuvant chemotherapy. This finding suggests that the two surgical approaches offer similar postoperative outcomes.

Purpose: Overall 5-year survival rates for colon and rectal cancer reported recently by the American Cancer Society were 89%, 90% for localized disease, 71%, 71% for regional disease, and 14%, 15% for distant disease. But the results of survival rate of colorectal cancer in a single institution were very rare. The aim of this study is to evaluate surgical results and survival rates of colorectal cancer. Methods: We conducted a retrospective study with patients who underwent curative resection for a primary colorectal adenocarcinoma between 2009 and 2018. Results: Five-year overall and disease-free survival were 79.5% and 69.9%, respectively. The overall 5-year survival by stages was 94.7% in stage I, 88.4% in stage II, 74.3% in stage III and 31.5% in stage IV. Five-year disease-free survival was 91% in stage I, 79.8% in stage II, 63.3% in stage III, and 18.9% in stage IV. The overall 5-year survival in rectal cancer was superior to colon cancer (P=0.014) while there was no difference in 5-year disease-free survival (P=0.338). Overall survival in female patients was better than male patient (P=0.029). Overall survival by age was worst in group of less than 40 years old (62.5%), and best in group between 41 and 65 years old (86.5%). Postoperative mortality within 30 days was 0.4%, and the recurrence rate was 19.2%. Conclusion With the development of surgical skills and various treatments, postoperative outcome of colorectal cancer is expected to improve. It may be helpful for surgeons to improve their surgical outcomes when they review their data and conduct active researches.