A Nomogram for Testosterone Recovery Following Combined Androgen Deprivation and Radiation Therapy for Prostate Cancer

Testosterone recovery (TR) after androgen deprivation therapy (ADT) and radiation therapy (RT) is not well characterized. We studied TR in men who received RT and either short-term (ST) or long-term (LT) ADT and aimed to create a nomogram to predict TR.

We identified consecutive localized PC patients treated with ADT-RT at two academic medical centers from 1/2011-10/2016 with documented baseline testosterone (T). TR was time from last ADT injection to T normalization. The Kaplan-Meier method was used to estimate time to TR. Cox proportional hazards models identified TR predictors. A nomogram was trained with site one and externally validated with site two.

340 patients were included. 69.7% received STADT, median duration 6 months; 30.3% received LTADT, median duration 24.3 months. Median follow-up was 26.7 months. Median time for TR was 17.2 months for STADT and 24.0 months for LTADT patients (p = 0.004). The 2-year cumulative incidence of TR was 53.1% after LTADT vs 65.7% after STADT (p=0.004). On multivariate analysis, shorter duration ADT (HR = 0.96, p = 0.004), higher pre-treatment T (HR = 1.004, p<0.001), and lower BMI (HR = 0.95, p = 0.002) were associated with shorter time to TR. Older age (HR = 0.97, p = 0.09) and white race (HR = 0.67, p = 0.06) trended as longer TR predictors. A nomogram was generated to predict probability of TR at 1, 2, and 3 years. The c-index was 0.71 (95%CI 0.64-0.78) for the validation cohort.

In this population of localized PC patients, TR following ADT-RT was variable. Using baseline T, ADT duration, BMI, age, and race, a predictive nomogram can estimate the likelihood of TR.

International journal of radiation oncology, biology, physics. 2018 Nov 09 [Epub ahead of print]

Daphna Y Spiegel, Julian C Hong, Taofik Oyekunle, Laura Waters, W Robert Lee, Joseph K Salama, Bridget F Koontz

Department of Radiation Oncology, Duke Cancer Institute, Durham, NC; Department of Radiation Oncology, Durham VA Medical Center, Durham, NC., Department of Biostatistics and Bioinformatics, Duke Cancer Institute, Durham, NC., Department of Radiation Oncology, Durham VA Medical Center, Durham, NC., Department of Radiation Oncology, Duke Cancer Institute, Durham, NC. Electronic address: .

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