Salvage high-dose-rate brachytherapy for recurrent prostate cancer

Background. Prostate cancer (PCa) is one of the most common malignant diseases in men worldwide, with over 1.1 million cases of PCa reported annually. In the Russian Federation, the proportion of patients with stage I—II PCa from 2008 to 2018 increased from 37.6 % to 56 %, which in turn allows more and more patients to perform radical treatment methods. However, it should be noted that the number of patients with both recurrent PCa after radiation therapy (external beam radiation therapy (EBRT) or brachytherapy) and with local recurrence after radical prostatectomy (RPE) is steadily increasing.

Objective. Improve treatment outcomes for patients with recurrent PCa.

Materials and methods. A. F. Tsyb Medical Radiological Research Center — branch of the National Medical Research Radiological Center, since 2016, has been treating patients with recurrent PCa using salvage high-dose brachytherapy (SHDR) (192Ir) after radical radiation treatment (EBRT, brachytherapy) or with local recurrence after RPE. Patients with recurrent PCa were divided into three groups, depending on the type of initial radical treatment: patients with recurrent disease after RPE, after EBRT and after brachytherapy.

Results. The most favorable results of SHDR were registered in the group of patients with local recurrence after RPE: in 7 patients out of 8 (87 %), one year after the PSA, the prostate-specific antigen (PSA) level was less than 0.1 ng/mL. In 1 patient, the PSA level dropped to 0.71 ng/mL (baseline 2.47 ng/mL) two years after salvage treatment. Currently, there is a further decrease in PSA levels.

Results after SHDR (¹⁹²Ir) in patients with relapse after EBRT: of 8 patients, 2 (25 %) had PSA levels less than 0.2 ng/mL after a year. In 4 patients, the PSA level two years after treatment was more than 2.0 ng/mL. In these patients, a relapse was registered. Another 2 patients also had a repeated relapse after SHDR.

The following results were obtained after carrying out SHDR in patients with relapse after braahythempy (both low- and high-dose). Of the 12patients, 7patients (58 %) had PSA levels less than 0.5 ng/mL two years after SHDR. SHDR was performed in the mode of two fractions of 12.5 Gyerahwith an interval of two weeks between them. In 3 patients, the PSA level exceeded 0.5 ng/ mL two years after the salvage treatment, and therefore, a second relapse is determined in them. Another 2 patients also had a repeated relapse.

Conclusion. This article provides preliminary results of our research. We would like to reiterate that as possible options for the treatment of local recurrence of PCa, it is possible to choose salvage prostatectomy, salvage radiation therapy, hormonal therapy or SHDR brachytherapy. In some cases EBRT is used in this category of patients, however, this can lead to the development of severe radiation damage. The choice of a treatment method in case of recurrent PCa is a complex problem, the decision of which is based on many factors. The clinical course of PCa, the prevalence of the disease, the level of markers, and molecular genetic data are taken into account.

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