In breast cancer patients, several regimens of neoadjuvant chemotherapy have been developed in order to achieve prognostic advantages for individual patients. Though some percentages of breast cancer patients show clinically complete response to neoadjuvant chemotherapy, the histopathological specimens of these patients demonstrate a considerably high frequency of the existence of residual disease. In this study, we aimed to evaluate the therapeutic effect of neoadjuvant chemotherapy for breast cancer patients showing clinically complete response (cCR) to neoadjuvant chemotherapy, using thin-section (5 mm) helical CT (prone position) with bolus injection of contrast agent. Between April 1994 and March 2002, 9 patients with breast cancer showing cCR to the neoadjuvant chemotherapy, who had undergone thin-section CT study both before and following neoadjuvant chemotherapy, enrolled in the study. The mean age of the patients was 46.2 years and all of them were female. The clinical stages were, 8 patients in stage II, and one in stage IIIA. In the CT evaluation, residual disease was visualized in 5 out of the 9 patients. Histopathological examination disclosed the existence of residual cancers in 6 out of the 9 patients, but only non-invasive cancer was revealed in 1 out of the 6. As patients having residual disease composed only of non-invasive cancer are classified into the pathologically complete response group according to the WHO classification, 4 out of these 9 patients showing clinically complete response to the neoadjuvant chemotherapy were classified into pCR (pathologically complete response) group, and another 5 were classified into the pPR (pathologically partial response) group. As a result, the diagnostic accuracy of the second CT study performed after neoadjuvant chemotherapy was evaluated as 77.8%, with a sensitivity of 80.0%, a specificity of 75.0%, a positive predictive value (PPV) of 80.0%, and a negative predictive value (NPV) of 75.0%. Therefore, for precise evaluation of the neoadjuvant chemotherapeutic effect for breast cancer, thin-section CT studies are considered to be essential.

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