Radiological Response Criteria
Radiological response criteria attempt to provide objective measures of tumor response to therapy. They are widely used as surrogate endpoints in clinical trials of cytotoxic chemotherapy and novel therapeutic agents.
The need for standardized and objective outcome criteria to measure response to anticancer treatment has been recognized for over 50 years. In 1960, the Eastern Cooperative Oncology Group proposed that objective measurement of tumor size should be used as an endpoint in the evaluation of cytotoxic chemotherapy, since killing tumor cells had been shown to reduce lesion dimensions.
These principles were first codified in the World Health Organization (WHO) document, published in 1979. In particular four categories of response to chemoradiotherapywere defined – complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD). While many early assessments of tumor size relied on clinical...