Rare cancers, while individually uncommon, account for over 20% of all cancer diagnoses worldwide and present distinct clinical and research challenges. This chapter explores the critical role of cancer cell lines in advancing rare cancer research, focusing on their utility as scalable, experimentally tractable platforms for molecular and pharmacological studies. Despite the rise of advanced models such as organoids and xenografts, conventional cell lines remain central to high-throughput investigations and multi-omics integration. Using osteosarcoma as a representative example, we analyze 226 cell lines catalogued in the Cellosaurus database. Our findings reveal that only a minority are both published in peer-reviewed literature and available from public repositories. Moreover, accessible models exhibit significant demographic and clinical biases, including underrepresentation of older patients and metastatic lesions—limiting their translational applicability. We highlight the importance of formally publishing newly established cell lines to ensure reproducibility, traceability, and community-wide use. While comprehensive characterization is ideal, excessive demands for omics data at the time of reporting may deter publication. We advocate for a balanced approach that ensures minimally sufficient documentation—such as donor metadata, STR profiling, and contamination testing—while allowing for future functional elaboration. To overcome systemic barriers, we propose structural reforms including clear editorial guidelines, publication incentives, and support for public cell banking. By fostering a culture of transparency and accessibility, the cancer research community can build a more inclusive and sustainable infrastructure to accelerate progress in the study of rare malignancies.