(P 55) CHONDROSARCOMA PATIENT CHARACTERISTICS AND DIAGNOSTIC AND TREATMENT PATHWAYS: GLOBAL CHONDROSARCOMA PATIENT REGISTRY

Objective: This descriptive analysis aims to explore the profiles of patients with chondrosarcoma (CS) worldwide.

Methods: This is a retrospective analysis of the Chondrosarcoma Patient Registry. The database includes demographic, medical history, diagnostic, clinical, genetic, and patient-reported measures collected from patients or their relatives worldwide via the customized survey (IAMRARE® program powered by the National Organization for Rare Diseases). Patients were stratified by sarcoma type in three cohorts – conventional CS (conventional grade 1-3 subtypes), non-conventional CS (other subtypes), and unknown CS (unspecified chondrosarcoma type). Outcomes were explored in the total sample and statistically compared between conventional and non-conventional CS. Quality of life was measured with the Global Health Questionnaire and converted into the Euro Qol 5-Dimensional 3-Level (EQ-5D-3L).

Results: The total sample consisted of 169 CS patients, with 32 conventional, 52 non-conventional, and 85 unknown (demographics in Table 1). Almost half of sample (50.3%) did not know their CS subtype (Figure 1). Most conventional CS cases had grade 2 disease (40.6%), while dedifferentiated CS was the most frequent non-conventional subtype (36.5%). Only half (49.7%) of patients had initial CS diagnosis, with 42.3% misdiagnosed patients among those who were not initially diagnosed with CS. Mean time from initial diagnosis to chondrosarcoma was 504 days. CS was mainly diagnosed by sarcoma specialists (34.9%) and pathologists (21.3%) most commonly using biopsy (69.2%) or MRI (67.5%). CS predominantly affected legs (right 14.2%, left 13.0%) and was associated with pain symptoms (64.5%). Non-conventional was more commonly located in left leg than conventional CS (23.1% vs. 3.1%, p=0.014) and associated with lump/swelling (44.2% vs. 18.8%, p=0.017). Symptoms occurred before diagnosis in 88.2% of patients (563 days from onset to CS). Only 3 patients (1.8%) had relatives with CS. Among patients with data on misdiagnosis status, 41.1% were not correctly diagnosed with CS. The mean time from misdiagnosis to CS diagnosis was 355 days. Recurrence was detected in 32.5% of patients (40.6% in conventional vs. 36.5% in non-conventional, p=0.708). Mean time from the first CS treatment to the recurrence was 800 days. Surgery was used to treat CS recurrence in 34.5% of patients, while 16.4% had no treatment. Metastases occurred in 29.0% of cases, with 37.5% in conventional and 34.6% in non-conventional CS patients.
CS treatments included surgeries (75.7%), radiation (26.0%), chemotherapy (14.8%), immunotherapy (4.7%), ablation (4.7%), and other medications (14.8%). The mean time from diagnosis to any treatment was 82 days, surgery 84 days, chemotherapy 345 days, radiation 681 days, and other medications 713 days. The mean EQ-5D-3L score was 0.65 without between-cohort differences (Figure 2).

Conclusion: The analysis provides a detailed description of the CS patient characteristics based on the worldwide CS registry data. The report offers valuable insight focusing on detailed characteristics of patients with each subtype of CS. CS is generally associated with the complicated diagnostic pathway including many diagnostic techniques and medical professionals. Despite the involvement of multiple medical professionals, CS is commonly misdiagnosed, with a long time period to establish the correct CS diagnosis.
Finally, these findings may help to improve patient outcomes by enhancing decision-making in clinical practice. The study also identifies the need for novel and effective CS treatments. Currently available treatment options are limited with high rates of recurrence and metastasis. EQ-5D-3L scores are low in CS patients in general, especially among conventional grade 3 and periosteal CS.
The main limitation of this analysis is survey-based data collection by patients or their relatives. Data may be compromised due to a lack of medical background and biased questionnaire completion.