Multiparametric prostate MRI-based intensity-modulated radiation therapy guided by prostatic calcifications

Area of Science:

• Radiation Oncology
• Medical Imaging
• Urologic Oncology

Background:

• The optimal method for delivering image-guided radiation therapy (IGRT) for prostate cancer is not well-established.
• Multiparametric prostate MRI is used for planning, but fiducial markers are often required for accurate targeting.
• Prostatic calcifications may offer a non-invasive alternative for image guidance.

Purpose of the Study:

• To evaluate the feasibility and outcomes of using prostatic calcifications as natural fiducial markers for IGRT in prostate cancer.
• To assess the impact of calcifications on treatment accuracy, toxicity, and biochemical control.

Main Methods:

• A cohort of 94 patients received CBCT-based IGRT without fiducial markers between 2015 and 2017.
• Multiparametric MRI was used for target delineation, with boosts to intraprostatic tumor nodules.
• The prevalence of prostatic calcifications was the primary endpoint; toxicity and biochemical control were secondary.

Main Results:

• Intraprostatic calculi were identified in 68% of patients.
• With a median follow-up of 39.7 months, 3-year biochemical control was 96%.
• Late grade ≥2 rectal toxicity was 3%, and late grade ≥2 urinary toxicity was 7%, unaffected by calcification presence.

Conclusions:

• Prostatic calcifications can effectively serve as natural fiducial markers for non-invasive IGRT in prostate cancer.
• This approach demonstrates promising early disease control and acceptable toxicity profiles.
• Image-guided radiation therapy guided by prostate calcifications is technically feasible.