Tumour volume analysis applied to imaging and histological examinations in breast cancer

Response Evaluation Criteria in Solid Tumours (RECIST) determines partial response (PR) and progressive disease (PD) as a 30 % reduction and 20 % increase in the longest diameter (LD), respectively. Tumour volume analysis (TVA) utilises three diameters to calculate response parameters.

We conducted a pilot investigation of patients who underwent neoadjuvant breast cancer treatment and evaluation using RECIST with LD measurements and TVA with three diametric measurements, using the parameters PR (>30 % tumour regression), PD (>20 % tumour growth), and intermediate stable disease (SD). According to TVA, RECIST miscategorised 7 of 28 patients (25 %). We evaluated 145 patients who underwent baseline breast magnetic resonance imaging (MRI), neoadjuvant chemotherapy, presurgical MRI, and surgery and calculated LD and volume from all MRI examinations.

Of the 173 patients, 157 had measurable disease at baseline and treatment completion, and 32 were miscategorised (20.4 %). The number of patients with a PR increased from 123 to 150 after TVA. The sensitivity of RECIST-measured responses (95 % confidence interval: 97-100 %) was 100 % for TVA. This altered the staging, as 32 of 157 (20.4 %) patients were allocated to another response group, with fewer cases of SD: 26 patients moved from SD to PR and 6 patients from SD to PD.

Measuring a solid mass using LD is fundamentally flawed, as the lesser axes considerably affect the volume, leading to inaccurate response categorisation, with implications for patient management. TVA is a novel method that increases accuracy of tumour size measurement and response to therapy.