The investigators found baseline testosterone, age, and the duration of ADT are significant predictors of testosterone recovery. The study, which analyzed data from five major randomized controlled trials involving 1,444 patients, demonstrates that testosterone recovery can vary significantly across individuals. The study also introduces a nomogram, a predictive tool that allows physicians to estimate recovery times based on patient-specific characteristics.

ADT, frequently used in combination with radiotherapy to treat prostate cancer, significantly lowers testosterone levels, leading to side effects such as fatigue, loss of libido and mood changes, which can impact patients' quality of life. Understanding testosterone recovery after ADT is crucial for improving patient outcomes, as it enables physicians to balance the cancer-fighting benefits of testosterone suppression with its debilitating side effects. This study provides a much-needed framework to help patients anticipate their recovery timeline and manage these side effects more effectively.

The researchers found recovery time is influenced by the length of ADT treatment, with older age and lower baseline testosterone levels associated with slower recovery. They also found that for men receiving six months of ADT, maintaining low testosterone levels for approximately 11 months may lead to improved metastasis-free survival, suggesting a longer suppression period may be beneficial even in shorter ADT regimens.

The results have important implications for clinical practice, especially as newer therapies offering rapid testosterone recovery are increasingly used. For men undergoing shorter ADT regimens, the findings suggest that slower recovery of testosterone, as seen with traditional therapies, may offer better cancer control.

"Our findings give patients and doctors valuable insights into what to expect after ADT treatment, helping them make informed decisions about managing side effects and improving long-term outcomes," said senior author of the study Dr. Amar Kishan, executive vice chair of radiation oncology at the David Geffen School of Medicine at UCLA.

The study was published in the journal European Urology.

The study's co-first authors are Tahmineh Romero from UCLA and Wee Loon Ong from Monash University in Melbourne, Australia. Other UCLA authors include John Nikitas, Michael Steinberg, Luca Valle, Matthew Rettig, Nicholas Nickols, Tommy Jiang, Robert Reiter and Sriram Eleswarapu.

The work was supported in part by grants from the National Institutes of Health, Radiological Society of North America, STOP Cancer, the Prostate Cancer Foundation, the U.S. Department of Defense and the UCLA Health Jonsson Comprehensive Cancer Center.