Oral Presentation NSW State Cancer Conference 2023

Treatment response assessment with quantitative imaging biomarkers in prostate cancer treated with radiation and androgen deprivation therapy (#51)

Yu-Feng Wang 1 2 , Sirisha Tadimalla 1 3 , Lois Holloway 2 4 , Niluja Thiruthaneeswaran 5 6 , Annette Haworth 1
  1. The University of Sydney, Camperdown, NEW SOUTH WALES, Australia
  2. Ingham Institute for Applied Medical Research, Sydney
  3. Sydney West Radiation Oncology Network, Western Sydney Local Health District, Sydney
  4. South Western Sydney Clinical School, University of New South Wales, Sydney
  5. Sydney Medical School, University of Sydney, Sydney
  6. Crown Princess Mary Cancer Centre, Westmead Hospital, Sydney

Introduction: Primary radiation therapy (RT) of prostate cancer (PCa), particularly high-risk disease, is commonly combined with neoadjuvant androgen deprivation therapy (ADT). As recurrence of PCa after RT is not uncommon, early detection of non-responding disease is needed to allow salvage therapies to be offered. [1] Quantitative parameters extracted from magnetic resonance imaging (MRI and qMRI parameters), correlated to underlying tissue biological and functional characteristics, can potentially provide a means for response monitoring and early detection of local recurrence. [2] The impact of ADT on the potential to monitor treatment response with qMRI parameters, however, remains unclear. In this prospective study, the potential of qMRI as a biomarker of response through RT in patients treated with and without ADT was therefore investigated.

Methods: Twenty-one patients were recruited to the Sequential Imaging Biofocussed Radiotherapy clinical trial (UTN U1111-1221-9589) between May and December 2019. Thirteen patients received neoadjuvant ADT prior to RT (2 – 4 months), with median duration of 22 months (range 4 – 24 months). Multiparametric MRI was acquired at pre-ADT (ADT patients only), pre-RT, and at 6-, 12- and 18- months post-RT. ADC, D, f, HS, R2*, T1, Ktrans, kep, ve maps were generated from diffusion weighted (DWI) and dynamic contrast enhanced imaging (DCE) at each time point and deformably registered to the baseline (first) scan. Tumour regions were segmented on the T2w, DWI, and ADC maps from the baseline scan using an inhouse developed deep learning model. Statistical significance of the treatment-related changes in the mean qMRI parameter values in the tumour was assessed with rANOVA and post hoc two-tailed t-test.

Results: The post-RT response kinetics of T1 and DWI-derived parameters were similar in both cohorts. In patients treated with ADT, the magnitude of changes were enhanced in DWI-derived parameters and diminished in T1 compared to non-ADT patients. Post-RT response kinetics in DCE-derived parameters varied between cohorts, with the onset of changes occurring prior to RT in patients with ADT. R2* changed significantly after RT in hormone naïve patients. While a significant change in R2* occurred after the initiation of ADT, the post-RT and pre-treatment values were comparable.

Conclusion: While all qMRI parameters, except f, demonstrated potential as biomarkers of treatment response, the post-RT kinetics and magnitude of qMRI parameter changes varied between patients treated with and without ADT. Predictive modelling of treatment response in PCa with qMRI parameters should be performed separately to account for effects of ADT.

  1. Spratt DE, McHugh DJ, Morris MJ, Morgans AK. Management of Biochemically Recurrent Prostate Cancer: Ensuring the Right Treatment of the Right Patient at the Right Time. Am Soc Clin Oncol Educ Book 2018;38(38):355-62.
  2. Wang C, Padgett KR, Su MY, Mellon EA, Maziero D, Chang Z. Multi-parametric MRI (mpMRI) for treatment response assessment of radiation therapy. Med Phys 2021.