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

Abstract

Purpose: 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.

Patients and methods: 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.

Results: 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.

Conclusion: 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.

Keywords: Breast cancer; Histology; Imaging; Tumor volume.