Purpose: This subgroup analysis of the Korean subset of patients in the phase 3 LASER301 trial evaluated the efficacy and safety of lazertinib versus gefitinib as first-line therapy for epidermal growth factor receptor mutated (EGFRm) non–small cell lung cancer (NSCLC). Materials and Methods: Patients with locally advanced or metastatic EGFRm NSCLC were randomized 1:1 to lazertinib (240 mg/day) or gefitinib (250 mg/day). The primary endpoint was investigator-assessed progression-free survival (PFS). Results: In total, 172 Korean patients were enrolled (lazertinib, n=87; gefitinib, n=85). Baseline characteristics were balanced between the treatment groups. One-third of patients had brain metastases (BM) at baseline. Median PFS was 20.8 months (95% confidence interval [CI], 16.7 to 26.1) for lazertinib and 9.6 months (95% CI, 8.2 to 12.3) for gefitinib (hazard ratio [HR], 0.41; 95% CI, 0.28 to 0.60). This was supported by PFS analysis based on blinded independent central review. Significant PFS benefit with lazertinib was consistently observed across predefined subgroups, including patients with BM (HR, 0.28; 95% CI, 0.15 to 0.53) and those with L858R mutations (HR, 0.36; 95% CI, 0.20 to 0.63). Lazertinib safety data were consistent with its previously reported safety profile. Common adverse events (AEs) in both groups included rash, pruritus, and diarrhoea. Numerically fewer severe AEs and severe treatment–related AEs occurred with lazertinib than gefitinib. Conclusion Consistent with results for the overall LASER301 population, this analysis showed significant PFS benefit with lazertinib versus gefitinib with comparable safety in Korean patients with untreated EGFRm NSCLC, supporting lazertinib as a new potential treatment option for this patient population.

Purpose: Liposarcoma is a mesenchymal neoplasm and comprise 20%–30% of all soft tissue sarcomas, accounting for 1% of all malignancies. This study documented the clinical manifestation and oncological outcomes of dedifferentiated liposarcoma (DDLPS). Materials and Methods: Eleven patients were diagnosed and treated for DDLPS between January 2013 and December 2020. The age, gender, symptom onset, tumor location, magnetic resonance images, surgical margin, and pathologic diagnosis of the identified cohort were reviewed. The time to local recurrence or metastasis, follow-up duration, and the patients’ final status were analyzed. Results: The patients comprised seven male and four female patients with a mean age of 59 years (43–73 years). The tumor location was in the thigh in five, inguinal in two, upper arm in two, forearm in one, and popliteal in one. The average tumor diameter was 12 cm (3.5–27.0 cm). At the time of diagnosis, one patient was American Joint Committee on Cancer stage IB, two were II, four were IIIA, and four were IIIB. Local recurrence occurred in four, and distant metastasis occurred in five. The five-year overall survival of patients with DDLPS was 54.5±17.6%, and four died due to disease progression. Conclusion Primary DDLPS in the extremities is a subtype of liposarcoma with a poorer prognosis than well-differentiated liposarcoma and myxoid liposarcoma.

Purpose: Giant cell tumor (GCT) of the proximal femur is relatively rare, with only a few case series reported thus far. This study aimed to evaluate the clinical outcomes of GCT of the proximal femur treated with intralesional curettage and expand the understanding of their characteristics and treatment considerations. Materials and Methods: Fifteen cases treated with curettage for GCT of the proximal femur between 2007 and 2020 were reviewed. The median follow-up was 46 months (25–150 months). There were 10 males and 5 females with a median age of 26 years (17–71 years). After curettage, the bone defect was filled with either an allograft (7 cases) or bone cement (8 cases). Results: The postoperative complications were local recurrences in three cases (20.0%), including malignant transformation in one case and a femur neck fracture in one case (6.7%) following curettage and strut allograft. Among the 15 cases, 13 (86.7%) retained their native joint at the last follow-up. No patients developed degenerative changes or osteonecrosis. Conclusion The results of proximal femoral GCT with curettage were acceptable despite local recurrences in three cases (20.0%), and femur neck fracture in one case. An appropriate surgical approach and reconstruction according to the extent of the lesion are necessary for successful treatment.

Background: Mechanical failures of tumor endoprosthesis in the distal femur usually require revision surgery. We investigated if the proximal femur host bone can be salvaged by onlay and overlapping allograft in revision surgeries due to aseptic loosening and stem fractures. Methods: We retrospectively reviewed 18 patients (7 men and 11 women) with osteosarcoma around the knee. The entire cohort was classified into three subgroups (no bone graft: 6, onlay allograft: 7, and overlapping allograft: 5) according to our treatment strategy. Results: The median interval from the initial surgery to the revision was 94.5 months (range, 21–219 months), and the median follow-up period from the revision surgery was 88.0 months (range, 24–179 months). At the last follow-up, 9 of the 18 patients maintained their endoprostheses, and the 5-year prosthesis survival rate was 57.9%. Limb survival was 100%. Five-year prosthesis survival rate was 66.7% in the no bone graft group, 85.7% in the onlay allograft group while 30.0% in the overlapping allograft group. In the no bone graft group and onlay allograft group, 66.7% (4/6) and 57.1% (4/7) maintained their revision prostheses while no prostheses survived in the overlapping allograft group. Recurrent stem loosening was observed in 14.2% (1/7) and 60.0% (3/5) of the onlay allograft and overlapping allograft groups, respectively, despite allograft bone union. The complication rate was 66.7% (12/18) in the entire cohort. The most common type of complication was infection (n = 6), followed by aseptic loosening (n = 4) and mechanical failure (n = 2). Conclusions This study indicates that onlay allograft can be used as a supportive method in revising failed endoprosthesis if the extent of host bone destruction is extensive. However, applying overlapping allograft to secure bone stock showed a high rate of mechanical failures and infection in the long term. Future studies with a larger cohort are necessary to assess the prognostic factors for the higher complication rate in overlapping allograft and the need for overlapping allograft. Surveillance with consideration of the risk of anteromedial osteolysis in allograft and efforts for prevention of periprosthetic infection are essential.

Tolvaptan reduces height-adjusted total kidney volume (htTKV) and renal function decline in autosomal dominant polycystic kidney disease (ADPKD). This study was aimed at investigating the efficacy and safety of tolvaptan in Korean patients with ADPKD during the titration period. Methods: This study is a multicenter, single-arm, open-label phase 4 study. We enrolled 108 patients with ADPKD (age, 19–50 years) with an estimated glomerular filtration rate (eGFR) of >30 mL/min/1.73 m2 and factors defined as indicative of rapid disease progression. After tolvaptan titration, we evaluated efficacy and side effects and assessed factors associated with the effects. Results: After titration for 4 weeks, eGFR and htTKV decreased by 6.4 ± 7.9 mL/min/1.73 m2 and 16 ± 45 mL/m, respectively. No serious adverse drug reactions were observed during the titration period. The greatest eGFR decline was observed in the first week, with a starting tolvaptan dose of 45 mg. Multivariate linear regression for htTKV decline showed that the greater the change in urine osmolality (Uosm), the greater the decrease in htTKV (β, 0.436; p = 0.009) in the 1D group stratified by the Mayo Clinic image classification. Higher baseline eGFR was related to a higher htTKV reduction rate in the 1E group (β, –0.642; p = 0.009). Conclusion: We observed short-term effects and safety during the tolvaptan titration period. The decline of htTKV can be predicted as a short-term effect of tolvaptan by observing Uosm changes from baseline to end of titration in 1D and baseline eGFR in 1E groups.

Purpose: Extraskeletal myxoid chondrosarcoma (EMC) is an extremely rare malignant mesenchymal neoplasm, accounting for less than 3% of soft tissue sarcomas. This sarcoma is usually characterized by its indolent course. This study examined the clinical manifestations and oncologic outcomes of EMC. Materials and Methods: Seventeen patients diagnosed and treated for EMC between January 2008 and December 2018 were enrolled in this study. The cohort was then reviewed regarding age, gender, symptom onset, tumor location, magnetic resonance images, surgical margin, and pathologic diagnosis. The time to local recurrence and metastasis, follow-up duration, and the patients’ final status were analyzed. Results: The patients were comprised of 10 males and seven female patients with a mean age of 54 (range, 31–79). The tumor location was the buttock in five, thigh in four, knee in three, foot in three, shoulder in one, and back in one. The average tumor diameter was 11.5 cm (range, 2.2–23.2 cm). At the time of diagnosis, five patients were American Joint Committee on Cancer stage II; three were IIIA; three were IIIB; six were IV. Local recurrence occurred in 12 cases, and distant metastasis occurred in 15 cases. The five-year overall survival of the patients with EMC was 73%±17%, and two patients died of the disease. Conclusion Despite the high rate of local recurrence and distant metastasis, the long-term survival rate in patients with EMC is quite high because of its indolent characteristics.

Purpose: This study examined the prevalence of osteoarthritis of the knee after curettage and polymethylmethacrylate (PMMA) application for giant cell tumor of the bone (GCTB) and factors affecting the development of osteoarthritis of the knee. Materials and Methods: Fifty-five patients with GCTB of the distal femur who were treated with curettage and PMMA filling between June 2001 and June 2016 were reviewed retrospectively. The development of osteoarthritis of the knee, as Kellgren–Lawrence grade 3 or 4, was determined by radiography of the latest follow-up data. This study evaluated the influence of the factors on the development of osteoarthritic changes. Only patients followed up for more than five years were included and the median follow-up was 77 months (range, 60–237 months). Results: Osteoarthritis of the knee was observed in 10 patients (18%) of whom three showed preoperative arthritic changes and did not progress. Seven (13%) patients experienced progression of the arthritic changes after surgery at a median of five years (range, 4–12 years). On the other hand, none of them received total knee arthroplasty. Among seven patients who showed progression of arthritis, four patients presented with a pathologic fracture initially and showed arthritic changes at a median of 4.5 years after surgery. The other three patients showed arthritic changes after ten years or more. Pathologic fractures (p=0.0001) and subchondral bone involvement (p=0.011) were significant risk factors for the development of osteoarthritis. Conclusion The incidence of development of osteoarthritis of the knee after curettage and PMMA application at distal femoral GCTB was 13%, but none of these patients received further surgery, such as total knee arthroplasty. The pathologic fracture and subchondral bone involvement are risk factors for arthritic changes in the midterm follow-up.

The genus Laccaria (Hydnangiaceae, Agaricales) plays an important role in forest ecosystems as an ectomycorrhizal fungus, contributing to nutrient cycles through symbiosis with many types of trees. Though understanding Laccaria diversity and distribution patterns, as well as its association with host plants, is fundamental to constructing a balanced plant diversity and conducting effective forest management, previous studies have not been effective in accurately investigating, as they relied heavily on specimen collection alone. To investigate the true diversity and distribution pattern of Laccaria species and determine their host types, we used four different approaches: specimen-based analysis, open database search (ODS), NGS analysis, and species-specific PCR (SSP). As a result, 14 Laccaria species have been confirmed in Korea. Results regarding the species distribution pattern were different between specimen-based analysis and SSP. However, when both were integrated, the exact distribution pattern of each Laccaria species was determined. In addition, the SSP revealed that many Laccaria species have a wide range of host types. This study shows that using these four different approaches is useful in determining the diversity, distribution, and host of ECM fungi. Furthermore, results obtained for Laccaria will serve as a baseline to help understand the role of ECM fungi in forest management in response to climate change.

Purpose: Periprosthetic fractures of a tumor prosthesis are rare but have difficulties in achieving sound fixation because of the poor bone quality, which increases the risk of loosening or re-fracture, even after bone union. A cortical strut onlay allograft was adopted for peri-prosthetic fractures after hip arthroplasty into the periprosthetic fracture of a tumor prosthesis, assuming that it would assist in firm fixation, shorten the time to union, and increase the bone stock, thereby, lower the chance of loosening and re-fracture. Materials and Methods: This study reviewed 27 patients (30 cases) of periprosthetic fracture of tumor prosthesis. Sixteen cases (allograft group) had augmentation with an onlay allograft, while 14 cases (conventional group) had internal fixation or conservative treatment.The following were assessed; mode of periprosthetic fracture, difference in the time to union between a strut cortical onlay allograft and without it, and survival of prosthesis, complication, and functional outcome between the two groups. Results: According to the unified classification system (UCS), 21 cases were type B (70.0%; B1, 14; B2, 1; B3, 6) and 9 cases were type C.The five-, 10-year survival of the 30 reconstructions by Kaplan–Meier plot was 84.5%±4.18% and 42.2%±7.83%, respectively. The average time to bone union of the entire cohort was 5.1 months (range, 2.0–11.2 months). The allograft group (3.5 months) showed a shorter period for union than the conventional group (7.2 months) (p<0.0001). All four cases of major complications occurred in the conventional group. Two cases with loosening and anterior angulation were treated with a change of prosthesis, and another with infection underwent amputation. The remaining case with loosening had conservative management. At the final follow-up, the average Musculosketal Tumor Society score of the allograft group (26.1) was better than that of the conventional group (20.9). Conclusion Bone union in periprosthetic fractures of a tumor prosthesis can be achieved, but the minimization of complications is important. An onlay allograft facilitates firm fixation and increases the bone stock with a shortened time to union. This simple method can minimize the risk of loosening, joint contracture, and re-fracture.