Prediction of survival benefit using an automated bone scan index in patients with castration-resistant prostate cancer.
What's known on the subject? and What does the study add? A bone scan index (BSI) can quantify the extent of bone involvement and response to treatment, but it has not been widely accepted, because of its time-consuming nature. The study is the first to demonstrate that automated BSI calculated with a computer-assisted diagnosis system is effective in judging the chemotherapeutic response of bone metastatic lesions in patients with castration-resistant prostate cancer.


OBJECTIVE
• To evaluate the value of an automated bone scan index (aBSI), calculated using a computer-assisted diagnosis system, to indicate chemotherapy response and to predict prognosis in patients with castration-resistant prostate cancer (CRPC) with bone metastasis.


METHODS
• Forty-two consecutive CRPC patients underwent taxane-based chemotherapy between November 2004 and March 2011 at our institution. • The aBSIs were retrospectively calculated at the diagnosis of CRPC and 16 weeks after starting chemotherapy. • Cox proportional hazards regression models were applied to multivariate analyses with and without aBSI response in addition to the basic model. • Based on the difference in the concordance index (c-index) between each model, the prognostic relevance of adding the aBSI response was determined.


RESULTS
• A decrease in aBSI was found in 28 patients (66.7%), whereas a response was shown by bone scan in only 23.8% of patients. • Patients with a reduction in aBSI had longer overall survival (OS) in comparison with the other patients (P= 0.0157). • Multivariate analysis without aBSI response showed that performance status (P= 0.0182) and PSA response (P= 0.0375) were significant prognosticators. • By adding the aBSI response to this basic model, the prognostic relevance of the model was improved with an increase in the c-index from 0.621 to 0.660.


CONCLUSIONS
• The aBSI reflected the chemotherapy response in bone metastasis. • The index detected small changes of bone metastasis response as quantified values and was a strong prognostic indicator for patients with CRPC.
Department of Urology, Shimane University School of Medicine, Izumo, Japan. mitsui@med.shimane-u.ac.jp
Yozo
Y
Mitsui
Hiroaki
H
Shiina
Yasushi
Y
Yamamoto
Masuo
M
Haramoto
Naoko
N
Arichi
Hiroaki
H
Yasumoto
Hajime
H
Kitagaki
Mikio
M
Igawa
D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality* / Q000556:secondary; D018450:Disease Progression; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009919:Orchiectomy; D011379:Prognosis; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000401:mortality / Q000556:secondary* / Q000601:surgery; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D051598:Whole Body Imaging / Q000379:methods*
D017430:Prostate-Specific Antigen