Focal or subtotal therapy for early stage prostate cancer

Current state of image-guided focal therapy for prostate cancer

PURPOSE

To review the current evidence regarding protocols and outcomes of image-guided focal therapy (FT) for prostate cancer (PCa).

METHODS

A literature search of the latest published studies assessing primary FT for PCa was carried out in Medline and Cochrane library databases followed by a critical review. FT modalities, follow-up strategies, and oncological and toxicity outcomes were summarized and discussed in this review.

RESULTS

Twenty-four studies with six different sources of energy met the inclusion criteria. A heterogeneity of patient selection, energy sources, treatment templates, and definitions of failure was found among the studies. While a third of patients may be found to have additional cancer burden over 3-5 years following FT, most patients will remain free of a radical procedure. The vast majority of patients maintain urinary continence and good erectile function after FT. Acute urinary retention is the most common complication, whilst severe complications remain rare.

CONCLUSION

An increasing number of prospective studies with longer follow-up have been recently published. Acceptable cancer control and low treatment toxicity after FT have been consistently reported. Follow-up imaging and routine biopsy must be encouraged post-FT. While there is no reliable PSA threshold to predict failure after FT, reporting post-FT positive biopsies and retreatment rates appear to be standard when assessing treatment efficacy.

Comparison of outcomes of salvage robot-assisted laparoscopic prostatectomy for post-primary radiation vs focal therapy

OBJECTIVES

To compare salvage robot-assisted laparoscopic prostatectomy (RALP) outcomes in patients who underwent radiation and those who underwent focal ablation as primary therapies.

PATIENTS AND METHODS

We evaluated 126 patients who underwent salvage RALPbetween 2008 and 2018. Of these, 94 (74.6%) received radiation and 32 focal ablation (25.4%) as primary therapy. These groups were compared with regard to clinical, oncological and functional outcomes. Kaplan-Meier curves and regression models were used to identify survival estimations and their predictors.

RESULTS

Before surgery, more patients were potent in the focal ablation group compared to the radiation group (46.9% vs 22.6%; P = 0.013). Peri-operative characteristics and complication rates were not significantly different between the two groups. Postoperative catheterization duration was shorter in the focal ablation group (mean 10 vs 16 days; P = 0.018). At final pathology, the focal ablation group had higher non-organ-confined disease (71% vs 50%; P = 0.042) and positive surgical margin (PSM) rates (43.8% vs 17%; P = 0.004) as compared to the radiation group; however, 5-year biochemical recurrence (BCR)-free survival rates were similar (59% vs 56%; P = 0.761). Postoperative 1-year full (no pads/day) and social (0-1 pad/day) continence rates were significantly higher in the focal ablation as compared to the radiation group (77.3% vs 39.2%, P = 0.002, and 87.5% vs 51.3%, P = 0.002, respectively). Multivariate analyses showed primary focal ablation and nerve-sparing to be predictors of postoperative continence. Erectile function was preserved in 13% and 27% of preoperatively potent patients in the radiation and focal ablation groups, respectively (P = 0.435). No predictors were identified for postoperative potency.

CONCLUSIONS

Radiation was associated with inferior functional outcomes after salvage RALP. Focal therapies were associated with higher non-organ-confined disease and PSMrates, with no significant difference in short-term BCR-free survival.

Risk of Upgrading from Prostate Biopsy to Radical Prostatectomy Pathology-Does Saturation Biopsy of Index Lesion during Multiparametric Magnetic Resonance Imaging-Transrectal Ultrasound Fusion Biopsy Help?

PURPOSE

We sought to determine whether saturation of the index lesion during magnetic resonance imaging-transrectal ultrasound fusion guided biopsy would decrease the rate of pathological upgrading from biopsy to radical prostatectomy.

MATERIALS AND METHODS

We analyzed a prospectively maintained, single institution database for patients who underwent fusion and systematic biopsy followed by radical prostatectomy in 2010 to 2016. Index lesion was defined as the lesion with largest diameter on T2-weighted magnetic resonance imaging. In patients with a saturated index lesion transrectal fusion biopsy targets were obtained at 6 mm intervals along the long axis of the index lesion. In patients with a nonsaturated index lesion only 1 target was obtained from the lesion. Gleason 6, 7 and 8-10 were defined as low, intermediate and high risk, respectively.

RESULTS

Included in the study were 208 consecutive patients, including 86 with a saturated and 122 with a nonsaturated lesion. Median patient age was 62.0 years (IQR 10.0) and median prostate specific antigen was 7.1 ng/ml (IQR 8.0). The median number of biopsy cores per index lesion was higher in the saturated lesion group (4 vs 2, p <0.001). The risk category upgrade rate from systematic only, fusion only, and combined fusion and systematic biopsy results to prostatectomy was 40.9%, 23.6% and 13.8%, respectively. The risk category upgrade from combined fusion and systematic biopsy results was lower in the saturated than in the nonsaturated lesion group (7% vs 18%, p = 0.021). There was no difference in the upgrade rate based on systematic biopsy between the 2 groups. However, fusion biopsy results were significantly less upgraded in the saturated lesion group (Gleason upgrade 20.9% vs 36.9%, p = 0.014 and risk category upgrade 14% vs 30.3%, p = 0.006).

CONCLUSIONS

Our results demonstrate that saturation of the index lesion significantly decreases the risk of upgrading on radical prostatectomy by minimizing the impact of tumor heterogeneity.

Discrepancy in prostate cancer localization between biopsy and prostatectomy specimens in patients with unilateral positive biopsy: implications for focal therapy

BACKGROUND

Unilateral ablative strategy success depends on reliable prediction of prostate cancer (PCA) location. We evaluated the discrepancy in PCA localization between unilateral positive biopsy (PBx) and radical prostatectomy (RP).

METHODS

Between 2004 and 2008, 431 patients were diagnosed with unilateral PCA by 12-core PBx; 179 underwent RP and constituted our study cohort. Specimens were reviewed to map tumor outline and determine number of cancer foci, tumor volume, Gleason score (GS), zone of origin, localization, and pathologic stage.

RESULTS

In 50 men, biopsy and prostatectomy findings correlated (unilateral tumor); in 129, PCA was detected in the contralateral side of the prostate. In 52 patients, 54 clinically significant tumors were missed by biopsy. When patients with true unilateral and missed contralateral disease at RP were compared with respect to prognostic parameters no significant differences were detected. Sixty-one of the 88 patients with preoperative low-risk disease had true unilateral (n = 21) or missed insignificant contralateral (n = 40) PCA; 27 had missed significant contralateral PCA at RP. PSA > 4 ng/ml predicted presence of significant bilateral disease in low-risk population (P = 0.004). Twenty-four of 27 patients with significant bilateral cancer had PSA > 4, although 33/61 with unilateral or bilateral insignificant cancer had similar elevated PSA values.

CONCLUSIONS

Twelve-core biopsy is inadequate to identify candidates for organ-sparing therapy. Most men with unilateral positive biopsies have bilateral cancer at prostatectomy. Tumors missed by biopsy were clinically significant in 40% of patients, but no prognostic parameters could predict unilateral disease. Hemi-ablative treatment might fail to eradicate significant lesions in the contralateral side.

Tumor focality in prostate cancer: implications for focal therapy

In recent years, there has been a growing interest in focal treatment for prostate cancer. Although widely used for the treatment of tumors of the breast and kidney, focal treatment for prostate cancer remains a controversial area. Criticism of focal prostate therapy has been based on the fact that prostate cancer is a multifocal disease. Until now, little attention has been paid to distinguishing between men with unifocal and those with multifocal disease because such information has little clinical relevance when treatment is aimed at the whole gland irrespective of the volume or number of cancers in the prostate. In this Review, we summarize existing knowledge and examine the issue of prostate cancer focality in the context of focal treatment.

Focal therapy in prostate cancer: modalities, findings and future considerations

Focal therapy is emerging as an alternative to active surveillance for the management of low-risk prostate cancer in carefully selected patients. The aim of focal therapy is long-term cancer control without the associated morbidity that plagues all radical therapies. Different energy modalities have been used to focally ablate cancer tissue, and available techniques include cryotherapy, laser ablation, high-intensity focused ultrasound and photodynamic therapy. The majority of evidence for focal therapy has come from case series and small phase I trials, and larger cohort studies with longer follow-up are only now being commenced. More data from large trials on the safety and efficacy of focal therapy are therefore required before this approach can be recommended in men with prostate cancer; in particular, studies must confirm that no viable cells remain in the region of ablation. Focal therapy might eventually prove to be a 'middle ground' between active surveillance and radical treatment, combining minimal morbidity with cancer control and the potential for re-treatment.

Impact of prostate cancer multifocality on its biology and treatment

Any focal therapy requires correct localization of the lesion; consequently, much effort is now devoted to accurate characterization of the spatial distribution of the tumor within the prostate. One of the greatest difficulties in the localization of prostate cancer is its frequent multifocality, but prostate cancer is unifocal in 13% to 43.7% of cases and unilateral in 19.2%. In cases of multifocality, it seems that the index tumor is the biologic driving force behind the malignant potential of prostate cancer. Not only is the Gleason score of the secondary nodes lower than that of the index node, but 80% of the secondary nodes are smaller than 0.5 cc and almost all extraprostatic extensions are associated with the largest cancers. While current evaluation with 12 to 18 core biopsies may be adequate to determine the index lesion, transperineal three-dimensional mapping biopsy of the prostate should be undertaken if greater accuracy is needed.

Nerve-sparing focal cryoablation of prostate cancer

PURPOSE OF REVIEW

We evaluate the rationale, candidate selection, and results of the first clinical studies of focal cryoablation for select patients with low volume and low-to-low - moderate risk features of prostate cancer as a possible alternative to whole gland treatment.

RECENT FINDINGS

For a select cohort of patients with low-to-low - moderate risk unifocal or unilateral prostate cancer, a number of ablative treatment options for focal therapy are available with cryotherapy having the most clinical experience. However, retrospective pathological data from large prostatectomy series do not clearly reveal valid and reproducible criteria to select appropriate candidates for focal cryoablation due to the complexity of tumorigenesis in early stage disease.

SUMMARY

The concept of focal therapy is evolving with the understanding of the biologic variability (clinically aggressive, significant, or insignificant) of prostate cancers that may require different treatment approaches. Minimally-invasive, parenchyma-preserving cryoablation can be considered as a potential feasible option in the treatment armamentarium of early stage, localized prostate cancer in appropriately selected candidates.

Prostate cancer: the new landscape

PURPOSE OF REVIEW

This review highlights current features of the changing landscape of the US population with newly diagnosed prostate cancer and discusses new treatment options utilizing noninvasive or minimally invasive management.

RECENT FINDINGS

Recent evidence of significant changes in the current prostate cancer landscape is based on clinical data and pathological specimens after radical prostatectomy that suggest a further increase of the low-risk patient population that may require reconsideration of treatment options. For a select cohort of patients with low-risk features, based on the D'Amico definition, active surveillance or focal ablative therapy may be a rational alternative to surgical prostatectomy or whole-gland radiation therapy that still dominate as the main treatment approaches for localized prostate cancer.

SUMMARY

As the prostate-specific antigen era continues to mature, we continue to witness stage migration. A growing segment of the localized prostate cancer patient population has very low-volume, low-grade disease. Although active surveillance may be an appropriate approach for a selected group of patients, the progression requiring whole-gland therapy remains a challenge. Organ-sparing focal therapy might ideally fill the gap between a surveillance strategy and whole-gland treatment providing a reasonable balance between cancer control and quality of life.