Editorial
Local Ablative Treatment in Oligometastatic Prostate Carcinoma
Elif Ozkan E*
Department of Radiation Oncology, OSM Middle East Health Center, Turkey
*Corresponding author: Elif Ozkan E, Department of Radiation Oncology, OSM Middle East Health Center, Turkey
Published: 16 Nov 2017
Cite this article as: Elif Ozkan E. Local Ablative Treatment
in Oligometastatic Prostate Carcinoma.
Clin Surg. 2017; 2: 1738.
Editorial
Aggressive local treatment approaches in oligometastatic prostate carcinoma is one of today’s
most important topic in prostate cancer treatment algorithm. Hellman and Weichselbaum were first
to define the notions oligometastases and oligo-recurrence [1,2] which are now widely accepted by
oncologists. Hellman and Weichselbaum also differentiate ‘true oligometastases’ which has limited
metastatic potential from ‘induced oligometastases’ occurring mostly after systemic treatment
with extensive malignant capacities and resistant [3]. In prostate cancer, induced oligometastases
includes patients with a rising PSA after primary therapy that has oligometastases on imaging or
castrate resistant patients with a rising PSA level and image detected oligometastases [4]. Radical
local treatment interventions like surgery or radiotherapy in oligometastatic patients is rationalized
through the sentiments that disease with 1–5 metastasis is at the beginning of progression shows
an attitude between localized and extensive stage. Consequently, long-term survival or cure can be
achieved with definitive local therapy in such selected cases [5].
Another important mechanism to explain this unexpected outcome in patients who are
treated with curative local radiotherapy is the abscopal effect. This is defined as vanishing of tumor
outside the radiation portal without systemic therapy. Abscopal effect is also reported in uterine
cervical cancer [6], hepatocellular cancer [7], malignant melanoma [8], and lymphoma [9]. This
phenomenon is reported to occur with surgery, as well radiation therapy [10]. Lussier et al. [11]
proposed tumour microRNA expression to differentiate the patients expected to live with stable
disease (≤5 lesions) or patients who have potential of developing polymetastatic progression. Patient
selection is the main issue in treatment decision of oligometastatic disease. Number and location
of lesions (single metastasis, 2-5 metastasis, multiple metastases in a single organ or multiple organ
metastases) are the most important means of selection. This warrants some featured imaging
modalities like Multi parametric MRI, Ga-68 Prostate specific membrane antigen PET/CT (PSMA
PET/CT) other conventional ones. A retrospective series of radical prostatectomy and extended
pelvic lymphadenectomy in men with metastatic prostate cancer by Sooriakumaran and colleagues
reported overall survival of 88.7% after a median follow-up of 22.8 months. Authors concluded that
radical prostatectomy for men with distant metastatic but locally resectable prostate cancer appear
safe in expert hands for selected patients [12].
Cho et al. [13] evaluated the efficacy and toxicity of curative local radiotherapy in metastatic
prostate cancer patients. In this study metastatic sites were divided into 4 groups: a) solitary bone, b)
2-4 bones, c) ≥5 bones, and d) visceral organs. Overall Survival (OS) and Biochemical Failure-Free
Survival (BCFFS) were improved in radiotherapy patients (3-year OS: 69% vs. 43%, p=0.004; 3-year
BCFFS: 52% vs. 16%, p=0.002). ECOG performance status, metastatic site, disease extent, and
prostate radiotherapy were significant factors for OS in univariate analysis. Multivariate analysis
confirmed significance of prostate radiotherapy as a predictor for OS (p=0.046). For BCFFS, only
prostate radiotherapy was found to be significant (p< 0.001) in univariate analysis. Conclusively,
authors suggested that radiotherapy to the primary tumor was associated with improved OS and
BCFFS in metastatic prostate cancer however they also impressed on the necessity of prospective
controlled clinical trials to encourage this approach in prostate cancer patients with limited extent
of bone metastasis and good performance status.
Culp et al. [14] evaluated men with documented stage IV (M1a-c) Prostate carcinoma at
diagnosis using Surveillance Epidemiology and End Results (SEER) (2004-2010). Totally 8185
patients were investigated for definitive treatment of the prostate (Radical Prostatectomy (RP) or
Brachy Therapy (BT)) or no local therapy. The 5-yr OS and predicted DSS were each significantly
higher in patients undergoing RP or BT compared with no local treatment (Table 1)). RP or BT were also independently associated with decreased cause specific mortality
CSM (p< 0.01). This study also confirmed the survival benefit of local
therapy in metastatic prostate carcinoma however could not tease
out that prospective trials are essential to recommend this approach
in daily practice. In another SEER database analysis metastatic
prostate cancer patients treated with radical prostatectomy, intensity
modulated radiation therapy, conformal radiation therapy or no local
therapy were identified. Decrease in the risk of prostate cancer specific
mortality was 52% and 62% for radical prostatectomy and intensity
modulated radiation therapy respectively. However conformal
radiation therapy did not improve survival compared to no local
therapy. As a conclusion authors suggested local therapy with radical
prostatectomy and intensity modulated radiation therapy but not
with conformal radiation therapy in metastatic prostate cancer [15].
Substantial amount of retrospective data encourages focal ablative
treatment oligometastatic prostate carcinoma while it is a unique
clinical state with indolent tumor biology. However, the basic question
is who will benefit most. In their study Yao et al. [16] suggested
that patients with fewer comorbidities, longer life expectancy, and
lower Eastern Cooperative Oncology Group performance status
are suitable for radical local treatment. Also, patients with target
lesion in a suitable location with a reasonable size and patients with
metastasis in organ composed of parallel functioning subunits with
considerable organ reserve (e.g. bone, lymph node, and lung, liver)
should preferably be considered for ablative local treatment.
Table 1
Table 1
The 5-yr OS and predicted DSS for patients with Radical Prostatectomy
(RP) or Brachy Therapy (BT)) or no local therapy.
Conclusion
1. Further prospective data are needed to select patients with
oligometastatic prostate cancer most likely to benefit from a radical
therapeutic approach. Highly sensitive imaging technology and
some molecular markers may be helpful to differentiate the suitable
patients.
2. Metastasis-directed approaches, such as stereotactic body
radiotherapy, are associated with minimal toxicity and excellent local
control; however, their effect on oncological outcomes is not proved
yet.
3. A multimodal approach to patients with oligometastatic
disease is warranted.
4. Local ablative therapies, such as prostatectomy and
radiotherapy, are reported to be safe and seem to reduce the need for
palliative treatment; however there is no level 1 evidence to support
its effect on survival outcomes and to suggest it as standard of care
yet [17].
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