FOCAL THERAPY – THE TARGETED TREATMENT METHOD FOR PROSTATE CANCER

When treating prostate cancer, the standard procedure is to remove or administer radiotherapy to the entire prostate. However, medical progress over the past few years has led to focal therapy emerging as a possible alternative to surgery and radiotherapy. In patients with prostate cancer, focal therapy only targets the part of the prostate actually affected by a tumour in need of treatment. The objective of this technique is to reduce side effects by preserving healthy tissue.

THE PROSTATE IS THE ONLY SOLID ORGAN THAT IS STILL NOT TREATED USING FOCAL THERAPY AS STANDARD.

The concept of organ preservation has long been the standard approach when treating other forms of cancer (e.g. breast cancer, kidney tumours). In fact, the prostate is the only solid organ that is still not treated using this approach as standard.

WHEN CAN PROSTATE CANCER BE TREATED USING FOCAL THERAPY?

 

Prostate cancer cells vary significantly in terms of their biological behaviour and their ability to metastasize. In 1998, an internationally recognised risk classification system was published for prostate cancer (see study 1 below).

  Low-risk Intermediate-risk High-risk
PSA <10 ng/ml 10 bis 20 ng/ml >20 ng/ml
Gleason-Score ≤6 7 8-10
Tumour grade T1 bis T2a T2b ≥T2c
Tabelle 1: Prostate cancer risk-based classification system (D’Amico criteria)

 

This classification system can be used to assess the prognosis of the disease. The prostate cancer is divided into three risk groups (low, intermediate and high risk) on the basis of the PSA level, a histological examination (Gleason score, tumour aggressiveness) and the clinical stage of the disease (Table 1). This system is known as the D’Amico classification and plays an important role when deciding which treatment to prescribe.

According to current expert opinion (Table 2), focal therapy can be used as an alternative to standard prostate cancer treatment options, such as active surveillance, surgery and radiotherapy, in men with a low to intermediate level of risk (see studies 2 and 3 below).

  • Life expectancy < 10 years
  • Localised tumour
  • Low to intermediate level of risk (Gleason 3+3, Gleason 3+4 and Gleason 4+3)
  • PSA ≤ 10 ng/ml
  • Index lesion
    – MRI and biopsy concordance, mpMRI/TRUS fusion biopsy
    – Systematic biopsies are mandatory, mapping biopsy!
Tabelle 2: Tay KJ, Scheltema MJ, Ahmed HU, et al. Patient selection for prostate focal therapy in the era of active surveillance: an International Delphi Consensus Project. Prostate Cancer Prostatic Dis. 2017;20(3):294-9.

WHICH FOCAL THERAPY TECHNIQUE CAN BE USED TO TREAT PROSTATE CANCER?

Several focal therapy techniques are currently available for treating prostate cancer in a way which preserves the organ. Focal therapy with HIFU (high-intensity focused ultrasound) is the method that has been researched for the longest and in the most detail to date. Other techniques include vascular-targeted photodynamic therapy (VTP), cryotherapy and irreversible electroporation (IRE). Generally speaking, the focal therapy options can be divided into thermal (HIFU, cryotherapy) and non-thermal (IRE) methods.

RISKS, SIDE EFFECTS AND TUMOUR CONTROL DURING THE FOCAL TREATMENT OF PROSTATE CANCER

A lot of data has already been compiled on risks, side effects and tumour control during the focal treatment of prostate cancer. The data was published in the most prestigious urological journal and presented in the following tables (see studies 4 and 5 below).

 

  Ablation Incontinence Erectile dysfunction Urinary retention
Cryotherapy Cold 1% 0-31% 5%
HIFU Heat 1% 0-31% 5%
IRE Electroporation 1% 5-10% 3%
Laser Heat 1% 5% 1%
PDT Vascular targeting 5% 2% 7%
Brachytherapy Radiation 5%
Radical prostatectomy   0-50% 29-100%
Table 3: Risks and side effects of various forms of prostate cancer treatment (van der Poel HG, van den Bergh RCN, Briers E, et al. Focal Therapy in Primary Localised Prostate Cancer: The European Association of Urology Position in 2018. Eur Urol. 2018;74(1):84-91.
  1 year 3 years 5 years
No metastases  99.7%   99%   98% 
Cancer-specific survival 100  100  100% 
Overall survival 100 99 
99% 
 
Table 4: Risks and side effects of various forms of prostate cancer treatment (van der Poel HG, van den Bergh RCN, Briers E, et al. Focal Therapy in Primary Localised Prostate Cancer: The European Association of Urology Position in 2018. Eur Urol. 2018;74(1):84-91.
Studies cited

cited studies

1. D’Amico AV, Whittington R, Malkowicz SB, et al. Biochemical outcome after radical prostatectomy, external beam radiation therapy, or interstitial radiation therapy for clinically localized prostate cancer. JAMA. 1998;280(11):969-74.

2. Donaldson IA, Alonzi R, Barratt D, et al. Focal therapy: patients, interventions, and outcomes–a report from a consensus meeting. Eur Urol. 2015;67(4):771-7.

3. Tay KJ, Scheltema MJ, Ahmed HU, et al. Patient selection for prostate focal therapy in the era of active surveillance: an International Delphi Consensus Project. Prostate Cancer Prostatic Dis. 2017;20(3):294-9.

4. van der Poel HG, van den Bergh RCN, Briers E, et al. Focal Therapy in Primary Localised Prostate Cancer: The European Association of Urology Position in 2018. Eur Urol. 2018;74(1):84-91.

5. Guillaumier S, Peters M, Arya M, et al. A Multicentre Study of 5-year Outcomes Following Focal Therapy in Treating Clinically Significant Nonmetastatic Prostate Cancer. Eur Urol. 2018;74(4):422-9.
„The main difference between IRE and the other focal therapies is that the NanoKnife method is not a thermal procedure. Thus, unpredictable side effects due to uncontrolled heat or cold can be avoided..“
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