Comparison of performance of various tumour response criteria in assessment of regorafenib activity in advanced gastrointestinal stromal tumours after failure of imatinib and sunitinib.

PURPOSE: To compare performance of various tumour response criteria (TRCs) in assessment of regorafenib activity in patients with advanced gastrointestinal stromal tumour (GIST) with prior failure of imatinib and sunitinib. METHODS: Twenty participants in a phase II trial received oral regorafenib (median duration 47 weeks; interquartile range (IQR) 24-88) with computed tomography (CT) imaging at baseline and every two months thereafter. Tumour response was prospectively determined on using Response Evaluation Criteria in Solid Tumours (RECIST) 1.1, and retrospectively reassessed for comparison per RECIST 1.0, World Health Organization (WHO) and Choi criteria, using the same target lesions. Clinical benefit rate [CBR; complete or partial response (CR or PR) or stable disease (SD)≥16 weeks] and progression-free survival (PFS) were compared between various TRCs using kappa statistics. Performance of TRCs in predicting overall survival (OS) was compared by comparing OS in groups with progression-free intervals less than or greater than 20 weeks by each TRC using c-statistics. RESULTS: PR was more frequent by Choi (90%) than RECIST 1.1, RECIST 1.0 and WHO (20% each), however, CBR was similar between various TRCs (overall CBR 85-90%, 95-100% agreement between all TRC pairs). PFS per RECIST 1.0 was similar to RECIST 1.1 (median 44 weeks versus 58 weeks), and shorter for WHO (median 34 weeks) and Choi (median 24 weeks). With RECIST 1.1, RECIST 1.0 and WHO, there was moderate concordance between PFS and OS (c-statistics 0.596-0.679). Choi criteria had less favourable concordance (c-statistic 0.506). CONCLUSIONS: RECIST 1.1 and WHO performed somewhat better than Choi criteria as TRC for response evaluation in patients with advanced GIST after prior failure on imatinib and sunitinib.

How to decide whether to offer and use "nonstandard" therapies in patients with advanced sarcomas and gastrointestinal stromal tumors: global variations in clinical practice, assessment, and access to therapies in diseases with limited incidence and data.

As cancer is more generally recognized as a collection of various rare diseases rather than a homogeneous illness, sarcomas have become a model for the manner in which data can and cannot be used to drive clinical decision making. In this article, we explore the limitations of data generated in rare diseases such as sarcomas to provide an evidence base for clinical practice. How should patients be treated if there is no "standard" that offers "proof" of clinical benefit? By asking this question, we also raise the issue of what constitutes "clinical benefit"-and how to measure that-for patients with sarcomas and other rare diseases. As physicians become more accountable for decisions-and yet are always accountable to the patients and families who rely on them to provide the best and most appropriate care-oncologists must be cognizant of the limitations of data in rare diseases and be ready to justify actions that are in the best medical and social interests of patients.

Gastrointestinal stromal tumors II: medical oncology and tumor response assessment.

The finding of mutations of KIT in gastrointestinal stromal tumors (GISTs) and subsequent development of kinase-directed therapy in metastatic GIST serve as a touchstone for the translation of laboratory research into clinical therapeutics. A variety of novel developments have followed the discovery of clinical activity of kinase-directed therapy against GIST. Radiological assessment of GIST challenges the standard of care for assessing tumor responses, ie, Response Evaluation Criteria in Solid Tumors (RECIST). Furthermore, the determination of the relationship of specific KIT mutations and sensitivity and resistance to kinase-directed agents and the assessment of inhibitor levels and the quality of response to those agents have implications beyond the treatment of sarcomas. These discoveries and the next chapters in this developing story are discussed in this review.

Use of erythropoietin in cancer patients: assessment of oncologists' practice patterns in the United States and other countries.

PURPOSE: To assess physician use of erythropoietin in cancer patients before publication of the American Society of Clinical Oncology/American Society of Hematology guidelines. METHODS: Questionnaires about erythropoietin use in practice and 12 hypothetical clinical scenarios involving patients with cancer were mailed to 2000 oncologists/hematologists in the United States and 19 other countries. Response rates were 30% in the United States and 25% internationally. Data on erythropoietin use for ovarian cancer were obtained from one clinical trial. Multivariate regression models assessed predictors of erythropoietin prescription. RESULTS: Most physicians selected a hemoglobin level < or =10 g/dL as an upper threshold for erythropoietin use (36% to 51% of U.S. physicians and 21% to 32% of foreign physicians). Frequent erythropoietin use (defined as use in at least 10% of cancer patients) was higher in the United States than elsewhere (adjusted odds ratio [OR] = 5.8; 95% confidence interval [CI]: 2.5 to 13.4). Among U.S. physicians, those who said they used erythropoietin frequently were more likely to be in fee-for-service than managed care settings (OR = 2.2; 95% CI: 1.3 to 3.7). Those who reported never using erythropoietin practiced in countries that had lower annual per capita health care expenditures, lower proportions of privately funded health care, and a national health service (P <0.05 for all comparisons). Of 235 ovarian cancer patients who received topotecan, 38% (45/118) of U.S. patients and 2% (2/117) of European patients who developed grade 1 anemia (hemoglobin level between 10 and 12 g/dL) were treated with erythropoietin (P <0.01). CONCLUSION: Financial considerations and a hemoglobin level <10 g/dL appear to influence erythropoietin use in the United States, whereas financial considerations alone determine erythropoietin use abroad.