Prognostic value of a computer-aided diagnosis system involving bone scans among men treated with docetaxel for metastatic castration-resistant prostate cancer

Abstract

BackgroundThe bone scan index (BSI), which is obtained using a computer-aided bone scan evaluation system, is anticipated to become an objective and quantitative clinical tool for evaluating bone metastases in prostate cancer. Here, we assessed the usefulness of the BSI as a prognostic factor in patients with metastatic castration-resistant prostate cancer (mCRPC) treated using docetaxel.MethodsWe analyzed 41 patients who received docetaxel for mCRPC. The Bonenavi system was used as the calculation program for the BSI. The utility of the BSI as a predictor of overall survival (OS) after docetaxel was evaluated. The Cox proportional hazards model was used to investigate the association between clinical variables obtained at docetaxel treatment, namely PSA, patient age, liver metastasis, local therapy, hemoglobin (Hb), lactase dehydrogenase (LDH), albumin (Alb), PSA doubling time, and BSI and OS.ResultsThe median OS after docetaxel therapy was 17.7 months. Death occurred in 22 (53.7 %) patients; all deaths were caused by prostate cancer. In multivariate analysis, three factors were identified as significant independent prognostic biomarkers for OS after docetaxel; these were liver metastases (yes vs no; HR, 3.681; p = 0.026), Alb (<3.9 vs ≥3.9; HR, 3.776; p = 0.020), and BSI (>1 % vs ≤1 %; HR, 3.356; p = 0.037). We evaluated the discriminatory ability of our models including or excluding the BSI by quantifying the c-index. The BSI improved the c-index from 0.758 to 0.769 for OS after docetaxel. CRPC patients with a BSI >1 had a significantly shorter OS than patients with a BSI ≤1 (p = 0.029).ConclusionsThe BSI, liver metastases and Alb were independent prognostic factors for OS after docetaxel. The BSI might be a useful tool for risk stratification of mCRPC patients undergoing docetaxel treatment.

Therapies for castration‐resistant prostate cancer in a new era: The indication of vintage hormonal therapy, chemotherapy and the new medicines

“…However, they sometimes experience that patients' symptoms worsen, and the results of imaging are poor even if an absolute value of the PSA is low. Furthermore, the PSA value might not become the prognostic marker . As advanced prostate cancer often metastasizes to bone, it is extremely important to evaluate the change of bone metastasis.…”

“…Furthermore, the PSA value might not become the prognostic marker. 62,63 As advanced prostate cancer often metastasizes to bone, it is extremely important to evaluate the change of bone metastasis. The extent of disease on bone scintigraphy was used to stratify the level of bone metastasis.…”

Editorial Comment to Bone scan index: A new biomarker of bone metastasis in patients with prostate cancer

“…reported that a BSI ≥1% predicted survival in metastatic castration‐resistant prostate cancer patients, whereas Miyoshi et al . reported a BSI ≥1.9% predicted survival in metastatic castration‐sensitive prostate cancer patients . Anand et al .…”

“…The BSI has been adopted in the assessment of bone metastasis among hormone‐naïve to hormone‐resistant prostate cancer . The cut‐off of the BSI in predicting worse survival varies from 1% to 5%.…”

“…Uemura et al reported that a BSI ≥1% predicted survival in metastatic castration-resistant prostate cancer patients, whereas Miyoshi et al reported a BSI ≥1.9% predicted survival in metastatic castration-sensitive prostate cancer patients. 4,5 Anand et al reported the change in BSI was useful in predicting survival in castrationresistant prostate cancer patients treated with enzalutamide. 3 In terms of a novel approach in radiographic assessment, trans-1-amino-3-18F-fluorocyclobutanecarboxylic acid positron-emission tomography was approved by the US Food and Drug Administration in 2016 as a new diagnostic imaging agent to detect recurrent prostate cancer.…”