Radiological measurement of breast cancer metastases to lung and liver: Comparison between WHO (bidimensional) and RECIST (unidimensional) guidelines

Purpose: Radiologic assessment of "response-to-treatment" during clinical trials of anticancer drugs has been conventionally based on bidirectional tumor measurement. Recently, the revised guidelines were published, which recommended unidirectional tumor measurements. The purpose of this study was to compare response to treatment between the two measurement techniques in breast cancer patients with lung and liver metastases. Method: Contrast-enhanced computed tomography studies of 86 breast cancer patients who had lung (n = 27) and liver (n = 59) metastases and who were enrolled in a phase-III oncology trial were evaluated before initiation of treatment and at 6 months after treatment. Lesions were measured by subspecialist radiologists on digitized images using electronic calipers. The largest diameter of the lesions was extracted from bidimensional measurements. Response to treatment was categorized into one of four categories: complete response indicating lesion disappearance, partial response indicating >30% decrease in tumor diameter, or >50% reduction in tumor area, disease progression indicating >20% increase in tumor diameter, or >25% increase in tumor area, and stable disease (neither complete response, partial response, nor disease progression). Response to treatment between the two measurement techniques was compared statistically using the χ² test. Results: Response to treatment was concordant in 76 patients between unidimensional and bidimensional measurement techniques. In 5 patients (2 lung and 3 liver metastases) the response assessment was improved using unidimensional criteria and in 5 patients (2 lung and 3 liver metastases) the response was worse using unidimensional guidelines. Thus, the overall response rate was 50% for both unidimensional and bidimensional measurement techniques. There was no statistical difference between the two techniques. Conclusion: Unidimensional measurements are appropriate for measuring the size of liver and lung metastases for determining response to treatment during clinical testing of oncologic drugs.