PET/CT imaging and the oligometastatic prostate cancer patient: an opportunity for a curative approach with high-dose radiotherapy?

Abstract

Although not curative, androgen deprivation (AD) therapy is presently the first treatment option for patients with recurrent and/or metastatic prostate cancer [1]. Metastatic prostate cancer most frequently becomes resistant to continuous AD after an average treatment time of 2 -3 years [2]. Furthermore, long-term AD may induce substantial side effects in patients compromising general health status and quality of life including cognitive and sexual impairment, fatigue, cardiovascular dysfunction, metabolic syndrome, loss of lean body mass, and osteoporosis [3][4][5]. Intermittent short courses of AD have been proposed as an alternative to continuous AD and tested in several phase II/III trials with the aim of reducing the severity and duration of the above-mentioned side effects and of delaying further the clinical appearance and progression of hormone-independent disease [6,7]. However, these trials have been unable to show a survival benefit of intermittent compared to continuous AD. Nevertheless, substrata analysis from a pre-PET/CT era randomized trial (RTOG 85-31) that recruited patients between 1987 and 1992 and compared continuous AD plus radiation with radiation alone in patients with pathological node-positive adenocarcinoma of the prostate showed 5-year biochemical control (i.e. PSA <1.5 ng/ml) in 54 % of the combined treatment arm versus 33 % of the radiation-only arm [8]. The 9-year absolute survival rate was 62 % in patients treated with combined treatment [8]. In other words, patients with disease in the pelvic or paraaortic lymph node regions treated with a combination of AD and curative intent radiotherapy can expect long-term survival despite their metastatic status.A large majority of patients with early biochemical failure after treatment of their primary tumour with curative intent have no evidence of disease on standard imaging such as bone scan or abdominal CT unless the PSA increases above 20 ng/ml [9]. PET/CT tracers for prostate cancer, including 11 C-acetate, 11 C-choline and 18 F-choline, were developed more than a decade ago and their role as reliable imaging tools for assessing the extension of disease in patients with biochemical failure in an earlier stage has slowly widened [10,11]. Head-to-head comparisons of these three different tracers are relatively scarce and frequently include only small numbers of patients. We have recently shown with PET/CT that 11 C-acetate and 18 F-choline produce very similar imaging results in patients with early relapse of prostate cancer [12]. The relapse status of local, regional and distant sites can be properly assessed with these imaging techniques so that the salvage treatment approach can be optimized.An oligometastatic status is not an uncommon clinical situation in patients with disseminated prostate cancer. Indeed, Harada et al. observed a large proportion of patients with one or two metastases in an autopsy series of 136 patients: 36 % and 32 % of patients had one and two bone lesions, respectively [13] . Only 10 % of patients had four or ...

The use of 68 Ga‐PSMA PET CT in men with biochemical recurrence after definitive treatment of acinar prostate cancer

“…These patients may be amenable to salvage surgical treatment with either a lymph node dissection or targeted radiotherapy to the nodal recurrence. Whilst a PSA >0.2 ng/mL is a common definition of biochemical recurrence, earlier detection of recurrence is desirable given the emerging field of oligometastatic treatment . Winter et al.…”

Volumetric Modulated Arc Therapy Planning for Primary Prostate Cancer With Selective Intraprostatic Boost Determined by 18F-Choline PET/CT

“…These results are consistent with the current study findings of higher TCPs associated with Plan 100-105Gy . It may be advantageous in terms of local tumor control to pursue both a high whole-prostate dose and a high boost differential, since a high boost dose at the expense of a lower whole prostate dose (< 70–75 Gy) has been associated with relatively high failure rates [39-42]. In contrast to the > 20 Gy differential boost dose of the current study, the average differential dose (PTV IDL –PTV prostate ) reported in a systematic review was 8 Gy (biologically effective dose 2 Gy per fraction, α/β = 3 Gy, range 3–35 Gy) and the most common rectal dose constraints used were V70Gy < 15–30% with D max of 76–80 Gy [8].…”

Defining Oligometastatic Disease in the New Era of PSMA-PET Imaging for Primary Staging of Prostate Cancer

“…In particular, multiple studies evaluating the use of stereotactic radiation or other focal therapy for the treatment of oligometastatic have relied heavily on PET/CT (with various radiotracers) due to a better selection of patients who are truly oligometastatic [38,39]. An early study evaluating the use of 11 C-choline PET/CT demonstrated that this approach could produce a useful single diagnostic exam in the evaluation of patients with moderate to high-risk prostate cancer with the potential of metastatic spread and can reliably rule out lymph node and distant metastases and establish eligibility for pelvic radiotherapy [40]. Another study found that the image-guided ablation of oligometastases identified by 11 C-choline PET/CT offered acceptable local tumor control rates and may allow for a delay of ADT initiation [41].…”